Lignin is an attractive, renewable raw material provided by all types of agricultural and silvicultural vegetation. The precipitation of lignin fractions through acidification of the black liquor was performed and the products characterized for the following parameters: C, H, N, and S elemental composition; zeta potential; electrophoretic mobility; heating value; molecular weight; content of non-conjugated, conjugated, and total phenolic hydroxyl groups; and total yield of oxidation products. Lignin was isolated from black liquor by adding sulphuric acid at four levels of concentration (5, 25, 50, and 72 wt%) and subsequently adjusting the pH to 5. A comparison study of the physico-chemical and surface properties was also performed. The acid concentration influenced the yield of precipitated lignin and had an effect on the properties of precipitated lignin and the content of non-conjugated, conjugated, and total amount of phenolic hydroxyl groups. However, the concentration of acid had no relevant effect on the heating value, molecular weight, polydispersity, total yield of oxidation products, or the elemental composition of isolated lignin.
Fractionation and characterization of lignins as and efficient tools for thei...Michal Jablonsky
Dissolution and fractionation of lignocellulosic material is a critical step of valorization of lignins. Content of dierent types of lignin precursors and the content of functional groups OH and OCH3 is aecting their utilization. Chemical and physical characterization of isolated lignin fractions is the key tool for further lignins
application. Presented work deals with the isolation of the lignin from the black liquor by the precipitation method, using a variety of acids. Properties of isolated lignin, preparations and different application and the possibilities of using lignins for various industrial sectors are presented.
CHARACTERIZATION AND COMPARISON BY UV SPECTROSCOPY OF PRECIPITATED LIGNINS AN...Michal Jablonsky
Five precipitated lignins and nine commercial lignosulfonates were investigated in this study. Lignins were
characterized by elemental analysis and as to ash content. To determine the amount of free phenolic groups in isolated precipitated and commercial lignosulfonates, ionization difference UV spectroscopy was used. The objective of this study was to examine the UV-Vis characteristics of precipitated and commercial lignin preparations in an effort to evidence their similarities and dissimilarities. Based on the experimental measurements, significant differences between the described lignins and lignosulfonates were identified. It was found that kraft lignin had a higher content of total amount of phenolic hydroxyl groups than lignin with straw (hemp and flax), isolated for modified alkaline anthraquinone cooking with different acids and commercial lignosulfonates. Moreover, it was confirmed that the content of non-conjugated and conjugated phenolic hydroxyl groups, as well as their total amount in the preparations depended on the method, raw material, and experimental conditions used in material processing.
osmotic dehydration as a tool for insdustrialization of jabuticaba peel (myrc...INFOGAIN PUBLICATION
This study evaluated the osmotic dehydration of jabuticaba peel for use as a by-product, with development of new food products. Response surface methodology was used, considering temperature and sucrose concentration as independent variables, assessing their effects on water loss, solid gain, mass loss, and solid gain rate. Sucrose concentration had a greater influence on osmotic process. Temperature increase is necessary in osmotic dehydration, once it leads to tissue softening, which is essential for dehydration of jabuticaba peel. Therefore, the best osmotic dehydration conditions were set at 60°C and 70 °Brix. With respect to the physicochemical characterization of the bioactive compounds of dehydrated jabuticaba peel, considerable amounts of sugars, anthocyanins, and phenolic compounds were observed, besides the antioxidant potential. Thus, dehydration of jabuticaba peel is a viable alternative to minimize the waste generated during harvest, being a product with high nutritional value.
Increment of carbohydrate concentration of Chlorella minutissima microalgae f...IJERA Editor
Microalgae, like any other microorganism react to changes in the external environment with changes in their
intracellular environment. Thus, the manipulation of cultivation conditions, especially the presence or absence
of certain nutrients, stimulates the biosynthesis of compounds of interest. Their carbohydrates can be used to
produce bioethanol. The objective of this study was to evaluate the effect of the medium and the concentrations
of nitrogen and phosphate components used in the culture medium of the microalgae Chlorella minutissima in
the carbohydrate concentration of the same. Box-Behnken Planning was used, totaling 15 trials. The cultivations
were carried out until early stationary phase of growth of the microalgae in closed 2 L reactors. At the end of the
cultivation, the carbohydrate concentrations of dry biomass (%) and yield in carbohydrates (g.L-1
.d-1
) were
determined. According to the analysis of effects, the microalgae Chlorella minutissima cultivated in Basal
medium, with the addition of 0.125 gL-1
of the nitrogenized component (KNO3) and without addition of
phosphatized components (K2HPO4 and KH2PO4) had a higher yield in carbohydrates in the cultivation (0,030 ±
0.002 g.L-1
.d-1
).
Determination of temperature regions in thermal degradation of ligninMichal Jablonsky
In this paper, industrial lignins were characterized by elemental analysis (EA) and thermogravimetry (TG). The aim was to find the main intervals of lignin degradation and maximum rate of their degradation. The results obtained can be helpful in finding the applicability of the materials at their thermal decomposition. The differences between individual lignins have been confirmed by EA and TG.
Fractionation and characterization of lignins as and efficient tools for thei...Michal Jablonsky
Dissolution and fractionation of lignocellulosic material is a critical step of valorization of lignins. Content of dierent types of lignin precursors and the content of functional groups OH and OCH3 is aecting their utilization. Chemical and physical characterization of isolated lignin fractions is the key tool for further lignins
application. Presented work deals with the isolation of the lignin from the black liquor by the precipitation method, using a variety of acids. Properties of isolated lignin, preparations and different application and the possibilities of using lignins for various industrial sectors are presented.
CHARACTERIZATION AND COMPARISON BY UV SPECTROSCOPY OF PRECIPITATED LIGNINS AN...Michal Jablonsky
Five precipitated lignins and nine commercial lignosulfonates were investigated in this study. Lignins were
characterized by elemental analysis and as to ash content. To determine the amount of free phenolic groups in isolated precipitated and commercial lignosulfonates, ionization difference UV spectroscopy was used. The objective of this study was to examine the UV-Vis characteristics of precipitated and commercial lignin preparations in an effort to evidence their similarities and dissimilarities. Based on the experimental measurements, significant differences between the described lignins and lignosulfonates were identified. It was found that kraft lignin had a higher content of total amount of phenolic hydroxyl groups than lignin with straw (hemp and flax), isolated for modified alkaline anthraquinone cooking with different acids and commercial lignosulfonates. Moreover, it was confirmed that the content of non-conjugated and conjugated phenolic hydroxyl groups, as well as their total amount in the preparations depended on the method, raw material, and experimental conditions used in material processing.
osmotic dehydration as a tool for insdustrialization of jabuticaba peel (myrc...INFOGAIN PUBLICATION
This study evaluated the osmotic dehydration of jabuticaba peel for use as a by-product, with development of new food products. Response surface methodology was used, considering temperature and sucrose concentration as independent variables, assessing their effects on water loss, solid gain, mass loss, and solid gain rate. Sucrose concentration had a greater influence on osmotic process. Temperature increase is necessary in osmotic dehydration, once it leads to tissue softening, which is essential for dehydration of jabuticaba peel. Therefore, the best osmotic dehydration conditions were set at 60°C and 70 °Brix. With respect to the physicochemical characterization of the bioactive compounds of dehydrated jabuticaba peel, considerable amounts of sugars, anthocyanins, and phenolic compounds were observed, besides the antioxidant potential. Thus, dehydration of jabuticaba peel is a viable alternative to minimize the waste generated during harvest, being a product with high nutritional value.
Increment of carbohydrate concentration of Chlorella minutissima microalgae f...IJERA Editor
Microalgae, like any other microorganism react to changes in the external environment with changes in their
intracellular environment. Thus, the manipulation of cultivation conditions, especially the presence or absence
of certain nutrients, stimulates the biosynthesis of compounds of interest. Their carbohydrates can be used to
produce bioethanol. The objective of this study was to evaluate the effect of the medium and the concentrations
of nitrogen and phosphate components used in the culture medium of the microalgae Chlorella minutissima in
the carbohydrate concentration of the same. Box-Behnken Planning was used, totaling 15 trials. The cultivations
were carried out until early stationary phase of growth of the microalgae in closed 2 L reactors. At the end of the
cultivation, the carbohydrate concentrations of dry biomass (%) and yield in carbohydrates (g.L-1
.d-1
) were
determined. According to the analysis of effects, the microalgae Chlorella minutissima cultivated in Basal
medium, with the addition of 0.125 gL-1
of the nitrogenized component (KNO3) and without addition of
phosphatized components (K2HPO4 and KH2PO4) had a higher yield in carbohydrates in the cultivation (0,030 ±
0.002 g.L-1
.d-1
).
Determination of temperature regions in thermal degradation of ligninMichal Jablonsky
In this paper, industrial lignins were characterized by elemental analysis (EA) and thermogravimetry (TG). The aim was to find the main intervals of lignin degradation and maximum rate of their degradation. The results obtained can be helpful in finding the applicability of the materials at their thermal decomposition. The differences between individual lignins have been confirmed by EA and TG.
Uv radiation assisted photocatalytic transformation of azo dye direct yellow 9eSAT Journals
Abstract
Advanced oxidation process (AOP) is best for treatment of textile industries effluents (waste water). Methylene blue immobilized resin dowex-11; a photocatalyst is used for transformation of azo dyes. The mechanism of the photo transformation depends on the radiation used. Activity of catalyst remains unaffected on continuous use. The process follows pseudo first order kinetics according to Langmuir Hinshelwood model, the value of rate constant k is 1.43*10-2 min-1 and approximately 94.60% of the dye was transforms within 160 min of irradiation.
Keywords: Transformation, Direct Yellow-9, Methylene blue immobilized resin, Textile effluents; Dowex-11, Photocatalyst.
Studies on Aminobenzothiazole and Derivatives: Part-1. Synthesis of Intermedi...BRNSS Publication Hub
1,3-Di(substituted-phenyl)-thiourea is used as intermediate in different reactions because they play an important role in synthesizing the different heterocyclic compounds. These reactions involve the synthesis of an intermediate, substituted-phenylammonium chloride which is converted to 1,3-Di(substituted-phenyl)-thiourea using ammonium thiocyanate. The final product formed, 1,3-Di(substituted-phenyl)-thiourea has potential to use as an intermediate in the synthesis of a building block for the heterocyclic compound, 2-aminobenzothiazole.
Chapter 13 Determination of riociguat using ninhydrin as a chromogen 2019Ratnakaram Venkata Nadh
A simple method is described to determine the amount of riociguat in bulk and tablet formulation by visible spectrophotometry. Formation of a chromophore with max of 597 nm, due to the reaction between the aromatic amine groups present on riociguat and ninhydrin in citric acid medium forms the basis for the current method. Extension of conjugation due to attachment of two ninhydrin molecules to a riociguat molecule explains the noticed high intensity as well as max of the generated chromophore. Current ICH guidelines were followed to validate the method. The obtained regression equation (y = 0.0316x+0.001) has a good correlation coefficient (> 0.999) in the studied range of 5.0-30.0 μg mL-1. Due to lack of separation steps in the method, it is found to be rapid as well as simple. The recovery levels of riociguat were in the range of 99.87 – 100.06.
Deep eutectic solvents (DESs) are a relatively new topic in science. Their usage is not yet clearly defined, and the areas in which DESs may be applied are constantly growing. A simple and clean fractionation of the main components of biomass represents a very important step in creating a clean, renewable carbon economy. A major challenge is the use of DESs for fractionation of biomass components at lower temperatures, without the use of expensive raw materials. In this work, wheat straw was pretreated with six different DES systems composed of choline chloride with urea (1:2), malonic acid (1:1), lactic (1:9; 1:10), malic (1:1), and oxalic acid (1:1). The pretreated biomass was characterized in terms of lignin content, ash, and holocellulose. A deep eutectic solvent, composed of choline chloride and oxalic acid, was found to produce the best delignification results. The solvents are not selective in the process of delignification.
Soil quality in the vicinity of palm oil mills in Umuahia, NigeriaPremier Publishers
The study focused on the effect of the palm oil mill effluent (POME) on the physico-chemical parameters of agricultural soil within Umuahia. The soil samples were collected from the areas where the POME was discharged. The following parameters were analyzed: particle size, organic carbon, organic matter, total nitrogen, total phosphorus, available phosphorus, exchangeable cations (Na, K, Ca, Mg), electrical conductivity. Digested samples were also analyzed for heavy metals (Cd, Cr, Ni, Cu) using an atomic absorption spectrophotometer. Results of the physico-chemical analysis showed that the discharge of POME onto the soil causes the degradation of soil physico-chemical properties and increase heavy metal contamination.
— Environmental care is an increasing concern in our society, and therefore integrated, circular economy allowing to close the industrial cycle is an urging demand. This project employs a residue of the food industry to recover the wastewaters from the textile industry, allowing closing the loop in two different industrial processes. Orange peel is a very abundant residue in the food industry. By chemical modification of the orange peel, we aim to produce a biosorbent to be employed in the treatment of the textile industry wastewater containing cationic dyes. In this project, we evaluate the capacity of the treated orange peels as cationic interchanger with different dissolutions of copper (II). Finally, their capacities as biosorbents were evaluated with four cationic dyes, examining the influence of different parameters like: biosorbent concentration, contact time, temperature and pH of the medium. An adsorption between 51 and 92 % was reached with the first treatment and also the possibility of the biosorbent recovery.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Mortar strength of Low calcium Flyashbased GeopolymerIOSRJEEE
Development of an alternative to conventional cement binder has become the essential need in the construction industries. Production of the conventional constituents of concrete particularly Portland cement exploits significant amount of natural resources and emits equivalent amountof carbon dioxide to the atmosphere. Research made on making binder without cement has come to a viable level of developing geopolymers.Industrial wastes and by products that are pozzolanic in nature are being used as source material and activated using alkaline solutions to use as binder. Considerable research has been carried out to study about the performance of geopolymer concrete with steam curing or hot curing which are feasible for precast concrete and practically not viable for conventional construction activities. However, there is not much data available on themortar strength.Abasic study on the strength characteristicsof low calcium flyash based geopolymer with 8-16M molar concentration of Sodium hydroxide and 1.5-3.0 liquid ratios of sodium silicate to sodium hydroxide. Both hot oven curingat 65oC and ambient curing at room temperature aremade. The results are compared and the optimum molarity for maximum strength is reported.
Lignin is a complex macromolecule structure found in plants. Through appropriate degradation of lignin it is possible to prepare chemicals with an added value. Therefore, it is important to use the best possible way for lignin degradation. Powerful method for characterization of the degradation is thermal analysis and the combination of pyrolysis with gas chromatography coupled with mass spectrometry. In this work, different commercial and prepared lignins were investigated.
The pH Behavior of Seventeen Deep Eutectic SolventsMichal Jablonsky
Deep eutectic solvents (DESs) are a unique category of green solvents that have gained attention in biomass processing due to their distinctive properties not offered by traditional solvents. The pH behavior of 17 selected DESs along with their temperature dependence on pH were evaluated in this study. For all investigated DESs, a temperature increase caused a decrease in pH value.
Uv radiation assisted photocatalytic transformation of azo dye direct yellow 9eSAT Journals
Abstract
Advanced oxidation process (AOP) is best for treatment of textile industries effluents (waste water). Methylene blue immobilized resin dowex-11; a photocatalyst is used for transformation of azo dyes. The mechanism of the photo transformation depends on the radiation used. Activity of catalyst remains unaffected on continuous use. The process follows pseudo first order kinetics according to Langmuir Hinshelwood model, the value of rate constant k is 1.43*10-2 min-1 and approximately 94.60% of the dye was transforms within 160 min of irradiation.
Keywords: Transformation, Direct Yellow-9, Methylene blue immobilized resin, Textile effluents; Dowex-11, Photocatalyst.
Studies on Aminobenzothiazole and Derivatives: Part-1. Synthesis of Intermedi...BRNSS Publication Hub
1,3-Di(substituted-phenyl)-thiourea is used as intermediate in different reactions because they play an important role in synthesizing the different heterocyclic compounds. These reactions involve the synthesis of an intermediate, substituted-phenylammonium chloride which is converted to 1,3-Di(substituted-phenyl)-thiourea using ammonium thiocyanate. The final product formed, 1,3-Di(substituted-phenyl)-thiourea has potential to use as an intermediate in the synthesis of a building block for the heterocyclic compound, 2-aminobenzothiazole.
Chapter 13 Determination of riociguat using ninhydrin as a chromogen 2019Ratnakaram Venkata Nadh
A simple method is described to determine the amount of riociguat in bulk and tablet formulation by visible spectrophotometry. Formation of a chromophore with max of 597 nm, due to the reaction between the aromatic amine groups present on riociguat and ninhydrin in citric acid medium forms the basis for the current method. Extension of conjugation due to attachment of two ninhydrin molecules to a riociguat molecule explains the noticed high intensity as well as max of the generated chromophore. Current ICH guidelines were followed to validate the method. The obtained regression equation (y = 0.0316x+0.001) has a good correlation coefficient (> 0.999) in the studied range of 5.0-30.0 μg mL-1. Due to lack of separation steps in the method, it is found to be rapid as well as simple. The recovery levels of riociguat were in the range of 99.87 – 100.06.
Deep eutectic solvents (DESs) are a relatively new topic in science. Their usage is not yet clearly defined, and the areas in which DESs may be applied are constantly growing. A simple and clean fractionation of the main components of biomass represents a very important step in creating a clean, renewable carbon economy. A major challenge is the use of DESs for fractionation of biomass components at lower temperatures, without the use of expensive raw materials. In this work, wheat straw was pretreated with six different DES systems composed of choline chloride with urea (1:2), malonic acid (1:1), lactic (1:9; 1:10), malic (1:1), and oxalic acid (1:1). The pretreated biomass was characterized in terms of lignin content, ash, and holocellulose. A deep eutectic solvent, composed of choline chloride and oxalic acid, was found to produce the best delignification results. The solvents are not selective in the process of delignification.
Soil quality in the vicinity of palm oil mills in Umuahia, NigeriaPremier Publishers
The study focused on the effect of the palm oil mill effluent (POME) on the physico-chemical parameters of agricultural soil within Umuahia. The soil samples were collected from the areas where the POME was discharged. The following parameters were analyzed: particle size, organic carbon, organic matter, total nitrogen, total phosphorus, available phosphorus, exchangeable cations (Na, K, Ca, Mg), electrical conductivity. Digested samples were also analyzed for heavy metals (Cd, Cr, Ni, Cu) using an atomic absorption spectrophotometer. Results of the physico-chemical analysis showed that the discharge of POME onto the soil causes the degradation of soil physico-chemical properties and increase heavy metal contamination.
— Environmental care is an increasing concern in our society, and therefore integrated, circular economy allowing to close the industrial cycle is an urging demand. This project employs a residue of the food industry to recover the wastewaters from the textile industry, allowing closing the loop in two different industrial processes. Orange peel is a very abundant residue in the food industry. By chemical modification of the orange peel, we aim to produce a biosorbent to be employed in the treatment of the textile industry wastewater containing cationic dyes. In this project, we evaluate the capacity of the treated orange peels as cationic interchanger with different dissolutions of copper (II). Finally, their capacities as biosorbents were evaluated with four cationic dyes, examining the influence of different parameters like: biosorbent concentration, contact time, temperature and pH of the medium. An adsorption between 51 and 92 % was reached with the first treatment and also the possibility of the biosorbent recovery.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Mortar strength of Low calcium Flyashbased GeopolymerIOSRJEEE
Development of an alternative to conventional cement binder has become the essential need in the construction industries. Production of the conventional constituents of concrete particularly Portland cement exploits significant amount of natural resources and emits equivalent amountof carbon dioxide to the atmosphere. Research made on making binder without cement has come to a viable level of developing geopolymers.Industrial wastes and by products that are pozzolanic in nature are being used as source material and activated using alkaline solutions to use as binder. Considerable research has been carried out to study about the performance of geopolymer concrete with steam curing or hot curing which are feasible for precast concrete and practically not viable for conventional construction activities. However, there is not much data available on themortar strength.Abasic study on the strength characteristicsof low calcium flyash based geopolymer with 8-16M molar concentration of Sodium hydroxide and 1.5-3.0 liquid ratios of sodium silicate to sodium hydroxide. Both hot oven curingat 65oC and ambient curing at room temperature aremade. The results are compared and the optimum molarity for maximum strength is reported.
Lignin is a complex macromolecule structure found in plants. Through appropriate degradation of lignin it is possible to prepare chemicals with an added value. Therefore, it is important to use the best possible way for lignin degradation. Powerful method for characterization of the degradation is thermal analysis and the combination of pyrolysis with gas chromatography coupled with mass spectrometry. In this work, different commercial and prepared lignins were investigated.
The pH Behavior of Seventeen Deep Eutectic SolventsMichal Jablonsky
Deep eutectic solvents (DESs) are a unique category of green solvents that have gained attention in biomass processing due to their distinctive properties not offered by traditional solvents. The pH behavior of 17 selected DESs along with their temperature dependence on pH were evaluated in this study. For all investigated DESs, a temperature increase caused a decrease in pH value.
A presentation giving the basic principles of corrosion. Electrochemical nature of corrosion, anodic and cathodic reactions, electrode potentials, mixed potential theory and kinetics of corrosion, thermodynamics of corrosion and Pourbaix diagrams, and passivization behavior of metals are outlined.
A SHORT REVIEW ON ALUMINIUM ANODIZING: AN ECO-FRIENDLY METAL FINISHING PROCESSJournal For Research
Protection of aluminium alloys is most commonly done by forming anodic films. Anodic films can also be formed on metals like titanium, zinc, magnesium, niobium, and tantalum. Aluminium alloy parts are anodized to greatly increase the thickness of the natural oxide layer for corrosion resistance. A thin aluminium oxide film, that seals the aluminium from further oxidation when it is exposed to air. The anodizing process increases the thickness of the oxidized surface. Anodizing is accomplished by immersing the aluminium into an acid electrolyte bath and passing an electric current through the medium. In an anodizing cell, the aluminium work piece is made the anode by connecting it to the positive terminal of a dc power supply and the cathode is connected to the negative terminal of the dc source. Sealing is needed to seal the pores in oxide layer to prevent further corrosion. Oxide layer on the anodized aluminium has a highly ordered, porous structure that allows for secondary processes such as dyeing, printing and sealing. Nanowires and nanotubes can be made by using the pores in the oxide layer as templates.
This lecture describes the process of anodic oxidation of aluminium, which is one of the most unique and commonly used surface treatment techniques for aluminium; it illustrates the weathering behaviour of anodized surfaces. Some familiarity with the subject matter covered in TALAT This lectures 5101- 5104 is assumed.
Thermal properties and size distribution of lignins precipitated with sulphur...Michal Jablonsky
Dissolution and fractionation of lignocellulosic material is a critical step of valorisation of lignins. Precipitated lignin was isolated from black liquor by sulphuric acid at four levels of concentration (5, 25, 50 and 72 % wt). A comparison study was performed through thermal and size properties. Theacid concentration influences of thermal properties of precipitated lignin. The acid concentration has an effect on changes in particle size of precipitated lignin. The results of thermogravimetric analysis indicated that the highest degradation of lignins appeared as an exothermic peak in range 470 - 650°C.The greatest weight loss in this section under an oxidation atmosphere was in the following order lignin 25 % wt (47.3 %), followed by lignin 72 % wt (45.0 %), lignin 5 % wt (43.6 %), and, smallest decline reached by lignin 50 % wt. The lowest temperature at the maximum degradation rate was determined for a sample of lignin 72 % wt at 488°C.
Characteristics of 2 Different Commercially Available Implants with or withou...Ali Alenezi
This animal study aims to observe the early bone forming properties of two commercially available implants,
One supposedly possessing nanostructures formed by ions bombardment.
and another chemically modified implant with calcium incorporated anodic oxidation
Aluminum anodizing: The study of the structure of the alumina layerSilio Moura
This work is focused on the study of the formation of an alumina (aluminum oxide) layer by double anodizing of aluminum. From this controlled oxidation method, a nanostructured porous layer with hexagonal cells was obtained. Ordered porous structures with 40-52 nm pore diameter were obtained by applying oxalic acid and a voltage-controlled procedure. The morphology of the surface and cross-section of the samples was analyzed by electron microscopy (Scanning and transmission). Finally, using this porous alumina as a template, Ni nanowires were obtained by electrochemical growth of the metal into the pores.
A presentation covering the various methods of prevention of corrosion. Material selection, design of structures, alteration of materials, alteration of environment, cathodic & anodic protection, and coatings are the different methods used. These are briefly described.
Lignin is one of the important components in the valorization of lignocellulosic biomass. Lignin-based materials and chemicals represent potential value-added products for biorefineries.
Lignin products have numerous applications and can be divided into three main groups. Group, in which lignin is fragmentized into smaller aromatic compounds such as phenol or benzene, toluene and xylene, is less developed than group where lignin is used as macromolecule, but has greater potential. Lignin as macromolecule is used as additive or polymer blend. Last group of lignin products are carbon materials, which include carbon fibres.
UV/Vis Spectrometry as a Quantification Tool for Lignin Solubilized in Deep E...Michal Jablonsky
In this short communication, UV/Vis spectrophotometry is described as an analytical tool for the quantification of lignin content in deep eutectic solutions. The lignin was solubilized with different deep eutectic solvent (DES). DESs were prepared as binary mixtures of choline chloride with lactic acid (1:9); (1:10); ethylene glycol (1:2); glycerol (1:2) and alanine:lactic acid (1:9), and betaine:lactic acid (1:2). The UV-Vis spectrometric quantification of the solubilized lignins was independent of the type of solubilized lignin. The approach consists of measuring the absorbance of a solution of lignins dissolved in the deep eutectic solvents at an absorbance of 440 nm.
RELATIONSHIPS BETWEEN ELEMENTAL CARBON CONTENTS AND HEATING VALUES OF LIGNINS Michal Jablonsky
Two precipitated lignins and seven commercial lignins were used in this study for predicting the correlation between higher heating values (HHV) and their carbon content. There was found a highly significant linear correlation between the HHV of the lignin and its C contents. The content of C was determined by elemental analysis. The HHV (MJ/kg) of lignin was calculated using the following equation: HHV = 0.40659(C), for which the correlation coefficient was: 0.9987. HHV prediction was applied to samples of 17 different lignins and data for 53 samples of several biomass resources obtained from literature. The HHVs calculated from this equation showed a mean difference of 0.49 % for different lignins and 2.13 % for biomass resources.
Removal of Lignin from aqueous solution using Fe3O4 Nanoparticles as an effec...IJERA Editor
The study was carried out to find out the adsorption efficiency of lignin from paper mill waste water by using Fe3O4 magnetic nanoparticles. The physico-chemical analysis of paper mill effluent results high B.O.D value. Separations of lignin from black liquor were done by acid precipitation method and removal of lignin was done with nanoparticles. Synthesis of nanoparticles was done by co-precipitation method by mixing and stirring of FeCl3.6H2O and FeCl2.4H2O solution at 2:1 molar ratio. The nanoparticles were characterized by using U.V-Vis spectrophotometer and X-Ray Diffraction. U.V-Vis spectra show absorbance spectra at around 585 nm while XRD revealed around 10 nm sizes of Fe3O4 MNPs. The removal efficiency of lignin by Fe3O4 MNPs was investigated at different pH and contact time. Maximum adsorption of lignin onto the surface of Fe3O4 MNPs took place at pH 2.5 and 10 mins of contact time. Desorption of lignin by nanoparticles was studies by using different organic solvents.
CITE: Hodasova, L., Jablonsky, M., Skulcova, A., Haz, A. (2015). Lignin, potential products and their market value. Wood Research, 60(6), 973-986.
Author "Michal Jablonsky" gives permission to use information and pictures from publications
Lignin is one of the important components in the valorization of lignocellulosic biomass. Lignin-based materials and chemicals represent potential value-added products for biorefineries. Lignin products have numerous applications and can be divided into three main groups. Group, in which lignin is fragmentized into smaller aromatic compounds such as phenol or benzene, toluene and xylene, is less developed than group where lignin is used as macromolecule, but has greater potential. Lignin as macromolecule is used as additive or polymer blend. Last group of lignin products are carbon materials, which include carbon fibres.
Chemical Composition and Thermal Behavior of Kraft LigninsMichal Jablonsky
Lignin has great potential for utilization as a green raw material or as an additive in various industrial applications, such as energy, valuable chemicals, or cost-effective materials. In this study, we assessed a commercial form of lignin isolated using LignoBoost technology (LB lignin) as well as three other types of lignin (two samples of non-wood lignins and one hardwood kraft lignin) isolated from the waste liquors produced during the pulping process. Measurements were taken for elemental analysis, methoxyl and ash content, higher heating values, thermogravimetric analysis, and molecular weight determination. We found that the elemental composition of the isolated lignins affected their thermal stability, activation energies, and higher heating values. The lignin samples examined showed varying amounts of functional groups, inorganic component compositions, and molecular weight distributions. Mean activation energies ranged from 93 to 281 kJ/mol. Lignins with bimodal molecular weight distribution were thermally decomposed in two stages, whereas the LB lignin showing a unimodal molecular weight distribution was decomposed in a single thermal stage. Based on its thermal properties, the LB lignin may find direct applications in biocomposites where a higher thermal resistance is required.
Profiling of Zn2+ Ion Sorption in Modeled Aqueous Solutions by different Part...IOSRJAC
The efficiency of the husk, stalk, cob and seed chaff from maize biomass in the removal of Zn2+ ions from solution under different conditions was studied and compared. Fourier Transform Infrared spectra of the different biomass parts before and after adsorption of metal ions showed that the husk and cob had more available functional groups and as such active sites for the adsorption of Zn2+ ions than the seed chaff and stalk. Percentage removal of Zn2+ions from solution increased with increase in the studied pH range for all the parts. This value also increased with increase in biomass load for the husk and cob but showed an alternating increase and decrease in Zn2+ ions removal as biomass load increased when the seed chaff and stalk were studied. At optimum pH and biomass load for the studied parts the maize husk gave the best removal efficiency of 72.8 %, making it a promising green packing material for industrial scale water treatment application.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Deep Eutectic Solvents: Fractionation of Wheat StrawMichal Jablonsky
Deep eutectic solvents (DESs) are a relatively new topic in science. Their usage is not yet clearly defined, and the areas in which DESs may be applied are constantly growing. A simple and clean fractionation of the main components of biomass represents a very important step in creating a clean, renewable carbon economy. A major challenge is the use of DESs for fractionation of biomass components at lower temperatures, without the use of expensive raw materials. In this work, wheat straw was pretreated with six different DES systems composed of choline chloride with urea (1:2), malonic acid (1:1), lactic (1:9; 1:10), malic (1:1), and oxalic acid (1:1). The pretreated biomass was characterized in terms of lignin content, ash, and holocellulose. A deep eutectic solvent, composed of choline chloride and oxalic acid, was found to produce the best delignification results. The solvents are not selective in the process of delignification.
ABSTRACT- Tagetes erecta L. was raised in pots containing soil treated with various concentrations of Pb(NO3)2 (500, 1000, 1500, 2000 and 2500mg/kg). At maturity plants were separated into root, stem, leaves and inflorescence and lead accumulated in each part was quantified. The effects of lead accumulation on growth was analyzed by the measurement of various growth parameters like root and shoot length, fresh and dry weight of root and shoot and total leaf area per plant. Moreover effect of lead accumulation on biochemical parameters was checked by quantitative estimation of various biochemical parameters like chlorophyll, total protein, free amino acids, total sugar, reducing sugar and starch. Results showed that there is no remarkable negative effect of accumulation of lead on the morphological growth of the plant. Biochemical analysis showed that amount of total protein continuously decreased whereas that of free amino acids continuously increased with increasing concentrations of lead. Amount of chlorophyll, total sugar, reducing sugar and starch contents continuously increased till mid-level i.e., Pb 1500 mg/kg and then continuously decreased at higher concentrations. Results of quantitative estimation of Pb in root, stem, leaves and inflorescence showed that roots accumulated highest amount of Pb followed by stem and leaves, whereas inflorescence contained least amount of Pb.
Key-words- Lead (Pb), Heavy metal, Tagetes erecta L., Accumulation, Phytoremediation
Potential of Neem Leaf Powder as Bio Adsorbents for Dye Colour Removalijtsrd
In this study, two types of eco friendly and low cost bio adsorbents, Neem leaf powder NLP and acid treated Neem leaf powder TNLP were prepared for the removal of dye color from Congo red solution. The physicochemical parameters of the prepared absorbents were measured. The structural features of these absorbents were analyzed by FTIR, XRD, and SEM. These experiments were conducted with different process parameters such as adsorbent dosage and agitating time using batch adsorption method. Firstly, the dosage amount of adsorbents was optimized for constant shaking for one hour and it was observed that the maximum percent adsorption was found at 91 of 0.4 g for NLP and 76 of 0.4 g for TNLP. The optimum dosage amount of adsorbents, 0.4 g was selected for further study. After optimizing the adsorbent dosage, the optimum agitating time was observed at 60 min with the percent removal of 91 for NLP and 76 for TNLP. From this research, it was observed that NLP and TNLP can be used as bio adsorbents to remove the color of the dye solution. Thet Thet Wai | Ei Mon Aung | Nyein Chan Kyaw "Potential of Neem Leaf Powder as Bio-Adsorbents for Dye Colour Removal" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd27987.pdfPaper URL: https://www.ijtsrd.com/engineering/chemical-engineering/27987/potential-of-neem-leaf-powder-as-bio-adsorbents-for-dye-colour-removal/thet-thet-wai
Synthesis and Characterization of Polymeric Drug Binder from Tobacco WastePremier Publishers
In Indian agriculture, tobacco has a prominent place. So, it is but natural that tobacco waste or dust is generated at various stages of post-harvest processing of tobacco and also while manufacturing various products. As rational production and processing of tobacco plant must include the entire biomass, both the main product leaves as well as stalks that remain after harvest. Residues (stalks and small leaves) and significant amounts of leaf scrap and waste generated during processing of tobacco, can serve as a very important secondary raw material from after final processing, a great number of products could be obtained in industry considering that these stalks contain a certain amount of cellulose. The waste obtained after nicotine extraction was utilized for cellulose extraction. The extracted cellulose was converted to value-added product such as cellulose acetate. Prepared cellulose acetate is characterized by Fourier transform infrared spectroscopy (FTIR).
Isolation, Screening, and Characterization of Biosurfactant-Producing Microor...BRNSS Publication Hub
Introduction: Biosurfactants are amphiphatic in nature and are surface-active compounds produced by microorganisms. These molecules reduce interfacial surface tension between aqueous solutions and hydrocarbon mixtures. Unfortunately, oil spills and industrial discharges from petroleum-related industries have been identified as the major pollution sources. The hydrophobicity and low aqueous solubility of petroleum pollutant limit the biodegradation process. The features that make biosurfactants as an alternative to commercially synthesized surfactants are its low toxicity, higher biodegradability and, hence, greater environmental compatibility, better foaming properties, and stable activity at extreme pH, temperature, and salinity. Objective: Therefore, in this study, hydrocarbon-degrading bacteria were screened from petroleum-contaminated soil, characterized and optimization of the physical and nutrient parameters were done to enhance the production of biosurfactants. Results: Petroleum-contaminated soil was collected from different petrol pumps in Pune and screening was done on minimal salt medium media containing palm oil as carbon source using hemolytic activity, emulsification index, drop-collapse test, and oil displacement method. The most promising strain was isolated and identified using Bergey’s Manual of Determinative Biology and 16s rRNA sequencing and was found to be Staphylococcus epidermidis. The optimization of various parameters, namely temperature, pH, carbon, and nitrogen sources on growth, and biosurfactant production was studied. The highest biosurfactant production was obtained when MSS media contains sucrose (carbon source) and urea (nitrogen source) at pH 10 and temperature 55°C. The Fourier transform-infrared (FT-IR) analysis of purified biosurfactant indicated the presence of lipopeptide biosurfactant when compared with reference FT-IR spectra.
Removal of Methylene Blue from Aqueous Solutions by Nitrated biomass of Cicer...IOSR Journals
Investigation of removal of methylene blue by nitrated biomass of Cicer arientinum is conducted in batch conditions. The effect of different parameters such as contact time, sorbent dose, pH and temperature has been studied. Adsorption kinetic modeling data were found out. The kinetics of biosorption results shows that sorption process is well explained by pseudo–second order model with determination coefficients higher than 0.99 for sorbent under all experimental conditions. The value Kp is found to be 0.652 to 2.43 for initial and final concentrations. Thermodynamic parameter via KD, ΔG has also been calculated to determine the spontaneity of the process. The low value of activation energy indicates that sorption is an activated and physical process. The Weber and Morris intraparticle diffusion model show liquid-film, mass transfer is effective sorption mechanism. Thus nitrated biomass of Cicer areintinum is a low cost and easily available efficiently used as an excellent sorbent for the removal of MB+ from wastewater. It can be safely concluded that biomass of Cicer arientinum is much economical effectual, viable and can be an alternative to more costly adsorbents.
Effluents containing heavy metals can be
remediated with the help of dead microorganisms by the process
known as biosorption. In this study the dead biomass 1of fungus
Aspergillus flavus was used for the biosorption of heavy metals
i.e., Zinc and Nickel. The capacity of biosorption by the dead
biomass of Aspergillus flavus was evaluated at room temperature
with different parameters which are; pH, contact time, biomass
concentration and metal ion concentration. The biosorption
capacity for Zn was found to be 47.36% at room temperature, at
pH 6.5, with biomass concentration of 2g/L having contact time of
50 min and solution concentration of 2ppm. Biosorption capacity
for Ni was found to be 61.60% at room temperature, at pH 5,
with biomass concentration of 2g/L having contact time of 60 min
and solution concentration of 2ppm. . In this study, desorption of
the heavy metals by 0.1M HCl was found to be effective. Fungal
biomass was recovered for reuse.
Similar to Characterization of non-wood lignin precipitated with sulphuric acid of various concentrations (20)
Green solvents show several favorable features to be used as extraction and fractionation solvents, such as their ease of preparation and lower cost, and they can be both non-toxic and biodegradable when prepared with natural compounds. Due to their properties, green solvents' application in biomass fractionation has been extensively studied during the past years. The presented work describes the application of several possible combinations to create deep eutectic solvents with the potential to be used in processing different types of biomass. The results of studies suggest that deep eutectic solvents may have an important ability to dissolve lignin molecules from plants and can realize a mild catalytic mechanism (acid-base) that will activate the checked cleavage of non-stable ether linkages between phenylpropane units.
Phytomass valorization by deep eutectic solvents - achievements, perspectives...Michal Jablonsky
In recent years, a plethora of extraction processes have been performed by a novel class of
green solvents known as deep eutectic solvents (DESs), possessing several environmental, operational,
and economic advantages proven by experience when compared to organic solvents and ionic
liquids. The present review provides an organized overview of the use of DESs as extraction
agents for the recovery of valuable substances and compounds from the original plant biomass,
waste from its processing, and waste from the production and consumption of plant-based food.
For the sake of simplicity and speed of orientation, the data are, as far as possible, arranged in
a table in alphabetical order of the extracted substances. However, in some cases, the isolation
of several substances is described in one paper and they are, therefore, listed together. The table
further contains a description of the extracted phytomass, DES composition, extraction conditions,
and literature sources. With regard to extracted value-added substances, this review addresses their
pharmacological, therapeutic, and nutritional aspects. The review also includes an evaluation of
the possibilities and limitations of using DESs to obtain value-added substances from phytomass.
Involvement of Deep Eutectic Solvents in Extraction by Molecularly Imprinted ...Michal Jablonsky
Substantial research activity has been focused on new modes of extraction and refining
processes during the last decades. In this field, coverage of the recovery of bioactive compounds and
the role of green solvents such as deep eutectic solvents (DESs) also gradually increases. A specific
field of DESs involvement is represented by molecularly imprinted polymers (MIPs). The current state
and prospects of implementing DESs in MIPs chemistry are, based on the accumulated experimental
data so far, evaluated and discussed in this minireview.
Investigation of Total Phenolic Content and Antioxidant Activities of Spruce ...Michal Jablonsky
Extracts from spruce bark obtained using dierent deep eutectic solvents were screened for
their total phenolic content (TPC) and antioxidant activities. Water containing choline chloride-based
deep eutectic solvents (DESs) with lactic acid and 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and
1,5-pentanediol, with dierent molar ratios, were used as extractants. Basic characteristics of the DESs
(density, viscosity, conductivity, and refractive index) were determined. All the DESs used behave
as Newtonian liquids. The extractions were performed for 2 h at 60 C under continuous stirring.
TPC was determined spectrophotometrically, using the Folin-Ciocalteu reagent, and expressed as
gallic acid equivalent (GAE). The antioxidant activity was determined spectrophotometrically by
2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The TPC varied from 233.6 to
596.2 mg GAE/100 g dry bark; radical scavenging activity (RSA) ranged between 81.4% and 95%.
This study demonstrated that deep eutectic solvents are suitable solvents for extracting phenolic
compounds from spruce bark.
Cellulose protectors for improving ozone bleaching - reviewMichal Jablonsky
Cellulose protectors (CPs) are able to eliminate an influence of degradating processes in ozone bleaching. Published literature reviews on using ozone in bleaching of pulps, issued
till the year 1992, have not contained any systematic classification of cellulose protectors by chemical groups. It has not dealt with evaluation of the effect of applied additives on the change of viscosity, kappa number and brightness either. In this work, we present a survey of the additives
applied in ozone bleaching from the year 1963 to 2003. Used CPs were systematically classified to 7 main chemical groups. The influence of used additives is evaluated on the basis of the change of viscosity, kappa number and the brightness compared to the ozone bleaching without additives
as for their positive and negative effect. The group of carboxylic acids can be ranked among the most effective additives, as regards the aspect of viscosity, elimination of lignin and brightness. Inorganic additives that were assessed usually have no positive influence on the protection of cellulose against degradation.
Deep Eutectic Solvent Delignification: Impact of Initial LigninMichal Jablonsky
This study aimed to resolve the issue of the lack of detailed understanding of the effect of initial lignin content in hardwood kraft pulps on pulp delignification by deep eutectic solvents. The authors used Kappa number of the concerned pulp, intrinsic viscosity, and selectivity and efficiency of delignification as the parameters of the effect. The pulp (50 g oven dry pulp) was treated with four different DESs systems based on choline chloride with lactic acid (1:9), oxalic acid (1:1), malic acid (1:1), and system alanine:lactic acid (1:9); the results were compared to those reached by oxygen delignification. The results showed that the pulp with a higher initial lignin content had a greater fraction of easily removed lignin fragments.
Mechanical Properties of Pulp Delignified by Deep Eutectic SolventsMichal Jablonsky
Mechanical properties were evaluated for pulp delignified by four deep eutectic solvents (DES). The DES systems were based on choline chloride and lactic acid (1:9), oxalic acid:dihydrate (1:1), malic acid (1:1), and the system alanine:lactic acid (1:9). The results indicated that the type of DES system used influenced the delignified pulp's mechanical properties including tensile, burst and tear indexes, tensile length, and stiffness. The most suitable DES systems were choline chloride:malic acid (1:1) and alanine:lactic acid (1:9), which achieved the best aforementioned mechanical properties compared to the other DES systems. The weakest performance in the process of pulp delignification was the system with choline chloride and oxalic acid dihydrate (1:1).
The pH Behavior of Seventeen Deep Eutectic SolventsMichal Jablonsky
Deep eutectic solvents (DESs) are a unique category of green solvents that have gained attention in biomass processing due to their distinctive properties not offered by traditional solvents. The pH behavior of 17 selected DESs along with their temperature dependence on pH were evaluated in this study. For all investigated DESs, a temperature increase caused a decrease in pH value.
THERMAL STABILITY OF SELECTED DEEP EUTECTIC SOLVENTSMichal Jablonsky
n this study, a new type of " green solvents " named deep eutectic solvents (DESs) has been synthesized combining hydrogen bond acceptors (HBAs) and hydrogen bond donors (HBDs). Choline chloride (ChCl) was chosen as typical HBA, and lactic acid, tartaric acid, citric acid and oxalic acidwere chosen as HBDs. The thermal stability of deep eutectic solvents is an important parameter for their application and limits the maximum operation temperature. The thermal stability of DESs such as lactic, tartaric, citric and oxalic acid with choline chloride showed wide range of application (134.8 – 197.8°C). All DESs were observed in temperature range 25 – 400°C.
Behaviors of Pulp During Delignification in Solutions of Deep Eutectic Solven...Michal Jablonsky
In this short communication, the degradation of cellulose for delignified pulp by deep eutectic solvents was evaluated. The pulp was delignified using different DES systems based on choline chloride and lactic acid (1:9), oxalic acid dehydrate (1:1), malic acid (1:1), and system alanine : lactic acid (1:9). This paper shows that cellulose degradation can be characterized in terms of the percentage degree of polymerization loss of cellulose. Among the investigated DES (Choline chloride:oxalic acid; choline chloride:malic acid; alanine:lactic acid; choline chloride:lactic acid), the most suitable seemed to be a treatment using the alanine:lactic acid system that provided a relatively low degradation of cellulose and high delignification efficiency for the removed of lignin from pulp.
Long-term Isothermal Stability of Deep Eutectic SolventsMichal Jablonsky
Deep eutectic solvents play an important role in the clean production of chemicals and the fractionation of renewable sources. When dissolving lignin or cellulose at elevated temperatures, the thermal stability of deep eutectic solvents is of great importance. However, studies concerning the long-term isothermal stability of deep eutectic solvents are scarce. In this study, the thermal stability of deep eutectic solvents, namely, choline chloride with oxalic acid dihydrate, glycerol, glycolic, malic acid, and citric acid monohydrate were investigated using thermogravimetric analysis (TGA). The isothermal decomposition experiments were conducted at a constant temperature (60, 80, 100, and 120 °C) for 10 h. These long-term isothermal thermogravimetric studies of the deep eutectic solvents showed a non-linear weight loss as a function of time at each temperature. According to these studies it is recommended to perform fractionation or dissolution of biomass below 80 °C.
Swelling properties of pulp treated with deep eutectic solventsMichal Jablonsky
The reaction of cellulose with water produces swelling and structural changes of the fibres, both effects being of crucial importance for the understanding of paper formation. It was investigated how the treatment of pulp with deep eutectic
solvents affects the swelling kinetics of the fibres. Unbleached kraft pulp was treated with three deep eutectic solvents containing choline chloride (ChCl) – ChCl:lactic acid (1:9), ChCl:oxalic acid (1:1) and ChCl:malic acid (1:1) – and with the system alanine:lactic acid (1:9). The rate and maximum swelling of the
pulp in water were determined using a modified monitoring unit for measuring swelling ability. Since paper swells extremely rapidly in water even at 23°C, this apparatus made it possible for the first time to obtain accurate rate data on the swelling of DES-delignified pulp in water.
Delignification of pulp with two ternary deep eutectic solvents: Urea-acetami...Michal Jablonsky
Using deep eutectic solvents (DESs), which ones act as solvent systems, offer an interesting green alternative to conventional technology in materials science, especially in the biomass processing. There is lack of information dealing with the delignification and bleaching effect of DESs in broad-leaved fiber process. This work describes application of various DESs on unbleached pulp, to study the influence of dissolution of lignin and protection of cellulose in the delignification process. In this work, two ternary deep eutectic solvents (urea-acetamide-glycerol) in molar ratio 1 : 2 : 3 and (malic acid-proline-lactic acid) in molar ratio 1 : 2 : 4 were synthesized and their density was studied in a temperature range of 25 to 75 0 C. Unbleached pulp (Kappa 14) was treated with prepared ternary deep eutectic solvents. The treatment was carried out in a water bath at present temperature of 60 0 C and atmospheric pressure for 2 hours. Solubility tests of cellulose were performed using pure cellulose (Whatman paper) in the DESs reagents. In 50 mL glass bottles, 0.5 g of the respective component was added separately into 20 mL of DES reagent and then incubated at 60 0 C for 2 h. The samples were filtered through glass fiber filters and dried at 105 0 C to constant weight. The weight of dried residual solid components was calculated in order to evaluate the % solubility in the DES reagent. Density of urea-acetamide-glycerol (molar ratio 1 : 2 : 3) decreased with a temperature from 1,220 to 1,199 g/cm 3 and density of malic acid-proline-lactic acid (molar ratio 1 : 2 : 4) decreased from 1,292 to 1,220 g/cm 3. Application of DESs to the lignocellulosic matrix pulp does not resulted in a significant decrease of lignin content. Deep eutectic solvent (urea-acet-amide-glycerol) in molar ratio 1 : 2 : 3 removed 5,4 % and DES (malic acid-proline-lactic acid) in molar ratio 1 : 2 : 4 removed 1.4 % lignin from unbleached pulp. The solubility of cellulose in ternary deep eutectic solvents was zero. Results show that prepared ternary deep eutectic solvents are able to delignify the pulp. However, the efficiency of delignification is not comparable to that of oxygen delignification. At the same time, used deep eutectic solvents do not cause dissolution of cellulose in pulp fibers.
Determination of the Thermal Oxidation Stability and the Kinetic Parameters o...Michal Jablonsky
The use of olive oil with cooking purposes, as final seasoning or within cooked foods is increasing worldwide due to its numerous nutritional and health benefits. These attributes are mainly determined by olive oil chemical composition, which can be altered after thermal processing, oxidation processes, or incorrect practices. For this reason, and due to the numerous factors which have influence in olive oil quality, the correct chemical characterization is highly relevant. In this study, fatty acid composition of four extra virgin olive oil (EVOO) varieties was studied. The major fatty acid (FA) determined was oleic acid (77.1% on average), followed by palmitic (11.5% on average). In addition, thermal oxidation behaviour of the four EVOO samples was studied as an indicator of their quality and stability during thermal processing. This was performed through differential scanning calorimetry (DSC) from a temperature of 40°C at six different heating rates in the range of 0.5–10°C min ⁻¹ . DSC records showed the same pattern and a small shoulder in the thermo-oxidation peak was present for all samples and all heating rates. The presence of initial and final oxidation products (by monitoring K232 and K270 values, respectively) was discarded according to the International Olive Council method.
Pharmacokinetic Properties of Biomass-extracted Substances Isolated by Green ...Michal Jablonsky
According to the literature, approximately 41 nutraceutical compounds have been isolated from different types of biomass using green solvents. It is important to collect information on the pharmacokinetic properties of the nutraceutical substances from biomass isolated according to the published papers. The pharmacokinetic properties of the bioactive substances extracted by green solvents, such as the molecular weight, logP, AlogP, H-bond acceptor, H-bond donor, total polar surface area, atom molar refractivity, number of rotatable bonds, number of atoms, rotatable bond count, number of rigid bonds, number of atom rings, and number of H-bonds, were calculated with a drug-likeness tool. In practical terms, the original and most well-known Lipinski's Rule of Five (Ro5) was applied to 28 substances, namely 3-hydroxytyrosol; apigenin; artemisinin; bergapten; bilobalide; biochanin A; caffeic Acid; caffeoylmalic acid; catechins; cinnamic acid; curcumin; daidzei; daidzin; epicatechin; gallic acid; genistein; ginkgolide A; ginkgolide B; levofloxacin; luteolin; naringenin; p-coumaric acid; protocatechuic acid; psoralen; quercetin; trans-ferulic acid; tyrosol, and vanillin.
Nutraceuticals as phenolic bioactive compounds analysis of softwood bark and ...Michal Jablonsky
Softwoods have a numerically large group of economically important renewable plants. Waste processing of trees mainly bark, needles are reasonable extent not recovered. The waste contains relatively high levels of phenolic compounds. Phenolic compounds are one of the main components that have a high potential in various fields of food, pharmacy, and other industries. This review focuses on the main uses of softwood bark and overviews the extraction and analytical methods used to determine phenolic bioactive compounds in this matrix. At this time, various extraction techniques are used to obtain secondary metabolites from bark mainly bio-active phenolic compounds. The amount of bioactive compounds derived from the matrix affects the: extraction conditions, choice of the solvent, particle size, content of the water and, in particular, the extraction method. Amount and nature of the isolated compounds greatly depend on the isolation; the isolation is possible to use different methods: extraction in a Soxhlet apparatus, Soxtec extraction, accelerated solvent extraction, ultrasound-assisted, supercritical fluid extraction, pressurized liquid extraction, and microwave assisted extraction. According to literature were selected nutraceuticals phenolic compounds (isolated from softwood bark):Astringin; Catechin; Epicatechin; Ellagic acid; Ferulic acid; Gallic acid; Hydroxymatairesinol; isolariciresinol; Isorhapontigenin; Isorhapontin,lariciresinol; Lariciresinol-9-p-coumarate; Methylthy mol;p-Coumaric acid; Piceatannol; Piceid; Podocarpic acid; Quercetin; Resveratrol; Sesquipinsapol B; Sinapic acid; Tannic acid; Taxifolin; Vanillic acid; Vladinol D. From this viewpoint, it is important to collect information on pharmacokinetic properties of the nutraceuti- cal phenolic substances isolated from bark according to published papers. Pharmacokinetics properties of phenolic bioactive substances extracted by different techniques such as: molecular weight, logP, AlogP, H-bond acceptor, H-bond donor, total polar surface area, atom molar refractivity, number of rotatable bond, number of atom, rotatable bond count, number of rigid bond, number of atom ring, and number of Hydrogen Bond were calculated by DruLito (Drug LiknessTool).
Determination of volatile organic compounds emissions from wood processingMichal Jablonsky
Volatile organic compounds (VOCs) have received a great deal of attention due to their high abundance during the drying process of wood particles. This is a potential environmental issue due to being low level ozone precursors. This work aimed to study the emissions of VOCs during drying in the particleboard manufacturing process. In this study, wood particles were dry and VOCs were collected using a sorption tube. The VOCs were analyzed with gas chromatography-mass spectrometry to explore the effect of temperature on the composition of main components. The results indicated that α-pinene and D-limonene were the dominant components. The results also indicated that using natural gas or wood dust as a heat source did not have a major impact on the emission characteristics of VOCs.
Assessing the main opportunities used of biomass, biowaste from forestry, agr...Michal Jablonsky
Valorisation of biomass and food-related wastes including extraction of value-added compounds from these sources represent a dynamically developed area of research and technology. Substantial research activity has been focused on the new types of extraction and refining processes during the last decades. In the presence of green solvents such as deep eutectic solvents (DESs), naturally deep eutectic solvents (NADESs), and low-transition temperature mixtures (LTTMs) the interest for the recovery of new products and bioactive compounds usable as additives and functional ingredients in industrial food sector with the aim to enhance food quality has been renewed and reinforced. DESs, NADES, and LTTMS are attractive solvents for the deconstruction/fractionation (or pretreatment) of biomass and modification of cellulose. The scope of this study consists in identifying the nutritional and nutraceutical potential of raw by-products, and in using possible processes for the production of individual compounds by separation, fractionation, and extraction. Another section is oriented on the application green solvents for fractionation of biomass or delignification/modification of pulp, and their valorisation for the product of added value (fibres, cellulose nanofibrils, cellulose nanocrystals). Acknowledgement This work was supported by the Slovak Research and Development Agency under the contracts No. APVV-15-0052, APVV-0393-14, APVV-16-0088 and VEGA grant 1/0403/19.
Delignification of pulp using deep eutectic solventsMichal Jablonsky
Lot of works during the last decades have been focused on the new modes of pulp processing. One promising technology is the use of deep eutectic solvents. Deep eutectic solvents (DES) have opportunities to open new paths in the field of delignification methods. This study was conducted to investigate the effects of deep eutectic solvent treatment on physical and chemical properties of delignified pulp. In the following experiment we used as an initial pulp the kraft pulp (Kappa No. 21.7; Degree of polymerization 1157). The pulp was treated with two different DES system based on choline chloride with lactic acid (1 : 9), and system alanine : lactic acid (1 : 9). The efficiency of delignification expressed as a decrease in kappa number on the unit change of the initial kappa number of pulp. The order by the delignification efficiency growth is as follows: choline chloride : lactic acid (37.8%) > alanine : lactic acid (43.3%). During delignification by DESs, a degradation of pulp chain occurs, however a decrease in degree of polymerization was only 23 units versus kraft unbleached pulp, which represents maximum decrease by 2%. Delignified pulp with DESs has a brightness 34% and unbleached pulp achieved brightness 27%, therefore, it achieves the increase in brightness by 26%.The physical strength properties of DES delignified pulps were assessed in terms of tensile, tear and burst index and stiffness. Application of deep eutectic solvents were achieved to reduce tensile index by 13.2%, burst index by 14.3% and a tear index by 9.8%, and the pulp stiffness was increased by 4% again the unbleached pulp. The results indicate that application of DESs might be an interesting alternative to oxygen delignification of pulp following kraft cooks.
Comparison of different extraction methods for the extraction of total phenol...Michal Jablonsky
Bark is an attractive renewable raw material, comprised of all types of silviculture vegetation. This renewable resource is a major alternative raw material for the food, chemical and pharmaceutical industry. Valorization is a key component of an economic lignocellulosic biorefinery. In this paper are included three extraction techniques and comparisons of total phenolic content. All extractions were done on milled spruce bark (Picea abies). Microwave assisted extraction; accelerated solvent extraction and extraction with deep eutectic solvents were used as a technique for extracts isolation. Choline chloride-based eutectic solvents with car-boxylic acids (maleic or malic acid) and glycerol were used as extractants. The extractions were performed for 1 h at 60 0 C with continuous stirring. Accelerated solvent extraction (extractant 96.6% ethanol; temperature (120, 140, 160 0 C) with steam pre-treatment (10, 20, 30 min.) was used as another type of extraction technique. The total phenolic content was determined spectrophotometrically at 764nm using the Folin-Ci-ocalteu method. This test is based on the oxidation of phenolic groups by phosphomolybdic and phospho-tungstic acids (FC reagent). Extraction technique using deep eutectic solvents brings results of phenolic contents in ranged from 900 to 2000 mg GAE per 100 g of dry bark. Samples with range of phenolic contents between 136.2 and 230.3 mg GAE per 100 g of dry bark were prepared by using acceleratet solvent extraction. Closed-system microwave assisted extraction (time 3 to 20 min.), and temperature (60; 80; 100 0 C) was applied to extract total phenolics from spruce bark, using 96.6% ethanol as an extractant. The total extracted phenolics, as assessed by Folin-Ciocalteu assay, varied between 90.3 and 321 mg gallic acid equivalence (GAE) per 100 g of dry bark for different temperatures. The results indicated that the highest amount of total phenolic compounds were found in extracts when using extraction by deep eutectic solvents
Sharpen existing tools or get a new toolbox? Contemporary cluster initiatives...Orkestra
UIIN Conference, Madrid, 27-29 May 2024
James Wilson, Orkestra and Deusto Business School
Emily Wise, Lund University
Madeline Smith, The Glasgow School of Art
Acorn Recovery: Restore IT infra within minutesIP ServerOne
Introducing Acorn Recovery as a Service, a simple, fast, and secure managed disaster recovery (DRaaS) by IP ServerOne. A DR solution that helps restore your IT infra within minutes.
Have you ever wondered how search works while visiting an e-commerce site, internal website, or searching through other types of online resources? Look no further than this informative session on the ways that taxonomies help end-users navigate the internet! Hear from taxonomists and other information professionals who have first-hand experience creating and working with taxonomies that aid in navigation, search, and discovery across a range of disciplines.
0x01 - Newton's Third Law: Static vs. Dynamic AbusersOWASP Beja
f you offer a service on the web, odds are that someone will abuse it. Be it an API, a SaaS, a PaaS, or even a static website, someone somewhere will try to figure out a way to use it to their own needs. In this talk we'll compare measures that are effective against static attackers and how to battle a dynamic attacker who adapts to your counter-measures.
About the Speaker
===============
Diogo Sousa, Engineering Manager @ Canonical
An opinionated individual with an interest in cryptography and its intersection with secure software development.
This presentation, created by Syed Faiz ul Hassan, explores the profound influence of media on public perception and behavior. It delves into the evolution of media from oral traditions to modern digital and social media platforms. Key topics include the role of media in information propagation, socialization, crisis awareness, globalization, and education. The presentation also examines media influence through agenda setting, propaganda, and manipulative techniques used by advertisers and marketers. Furthermore, it highlights the impact of surveillance enabled by media technologies on personal behavior and preferences. Through this comprehensive overview, the presentation aims to shed light on how media shapes collective consciousness and public opinion.
This presentation by Morris Kleiner (University of Minnesota), was made during the discussion “Competition and Regulation in Professions and Occupations” held at the Working Party No. 2 on Competition and Regulation on 10 June 2024. More papers and presentations on the topic can be found out at oe.cd/crps.
This presentation was uploaded with the author’s consent.
Bitcoin Lightning wallet and tic-tac-toe game XOXO
Characterization of non-wood lignin precipitated with sulphuric acid of various concentrations
1. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1408
Characterization of Non-wood Lignin Precipitated with
Sulphuric Acid of Various Concentrations
Igor Šurina,a,
* Michal Jablonský,a
Aleš Ház,a
Alexandra Sladková,a
Anna Briškárová,b
František Kačík,b
and Jozef Šima c
Lignin is an attractive, renewable raw material provided by all types of
agricultural and silvicultural vegetation. The precipitation of lignin
fractions through acidification of the black liquor was performed and the
products characterized for the following parameters: C, H, N, and S
elemental composition; zeta potential; electrophoretic mobility; heating
value; molecular weight; content of non-conjugated, conjugated, and
total phenolic hydroxyl groups; and total yield of oxidation products.
Lignin was isolated from black liquor by adding sulphuric acid at four
levels of concentration (5, 25, 50, and 72 wt%) and subsequently
adjusting the pH to 5. A comparison study of the physico-chemical and
surface properties was also performed. The acid concentration
influenced the yield of precipitated lignin and had an effect on the
properties of precipitated lignin and the content of non-conjugated,
conjugated, and total amount of phenolic hydroxyl groups. However, the
concentration of acid had no relevant effect on the heating value,
molecular weight, polydispersity, total yield of oxidation products, or the
elemental composition of isolated lignin.
Keywords: Selectively precipitated lignin; Black liquor; Sulphuric acid; Renewable raw materials
Contact information: a: Slovak University of Technology, Faculty of Chemical and Food Technology,
Institute of Natural and Synthetic Polymers, Department of Wood, Pulp and Paper, Radlinského 9,
Bratislava, 812 37, Slovak Republic; b: Department of Chemistry and Chemical Technologies, Faculty of
Wood Sciences and Technology, Technical University in Zvolen, T.G. Masaryka 24, Zvolen, 960 53, Slovak
Republic; c: Department of Inorganic Chemistry, Radlinského 9, Bratislava, 812 37, Slovak Republic;
*Corresponding author: igor.surina@stuba.sk
INTRODUCTION
The worldwide increase in the price and cost of petroleum and coal has created an
interest in alternative sources of raw materials. Biomass is an attractive renewable raw
material comprising all types of agricultural and silvicultural vegetation. This renewable
resource is considered to be a major alternative raw material for the chemical industry.
For many years, wood chemistry has tried to find applications for lignins other than their
use as fuel and to valorize lignin byproducts. Lignin in wood and annual plants may be
considered to be a random three-dimensional network polymer composed of
phenylpropane units linked together in different ways (Rosas et al. 2004). When
lignocellulose materials are delignified, the properties of the macromolecules reflect the
properties of the network from which they are derived. Most of this biomass is burned as
fuels. A small portion is applied (Vishtal and Kraslawski 2011) as carriers, e.g. for
fertilizers and pesticides, carbon fibers, blends with thermoplastic polymers, ion-
exchange resins, activated carbons. Part is transformed into chemical compounds such as
vanillin, hydroxylated aromatics, quinones, aldehydes, aliphatic acids. Lignocellulose is
2. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1409
also used in production of phenolic resins, dispersants, mew polymers, detergents, glues,
binders and resins, adhesives, feeds, and cement additives.
Larger fractions of material could be used in other industrial and commercial
processes if an economical method could convert lignin into a marketable product with
sufficient profit margin. Lignin valorisation is a key factor for an economical
lignocellulosic biorefinery. Many possible structures could be derived from the guaiacyl
and syringyl units present in lignin (Holladay et al. 2007).
Currently, only about 2% of the lignins available in the pulp and paper industry
are commercially used, comprising about 1,000,000 tons/year of lignosulphonates
originating from sulphite pulping and less than 100,000 tons/year of kraft lignins
produced in the kraft process (Gosselink et al. 2004). Dissolution and fractionation of
lignocellulosic material is a critical step in the valorisation of biomass (Zakzeski et al.
2010; Vishtal and Kraslawski 2011). Fractionation of biomass, however, is not easy.
Many treatment strategies have been developed to isolate lignin with a high yield. These
methods (Sun et al. 2011) cover physical (pulverisation, irradiation, ultrafiltration
(Toledano et al. 2010a; 2010b)), chemical (alkali, acid (Tejado et al. 2007; Garcia et al.
2009; Minu et al. 2012), organosolv, ionic liquid (Sun et al. 2013), hot water (CO2
explosion, wet oxidation), biological (enzymolysis), and electrical methods or some
combinations of these techniques (Mosier et al. 2005).
Black liquor is a highly complex mixture, and the composition of the precipitated
lignin depends on the conditions of precipitation (Ibrahim et al. 2004; Tejado et al. 2007;
Garcia et al. 2009; Toledano et al. 2010a; 2010b; Minu et al. 2012) such as the type of
acid, temperature, method of isolation (filtration, ultrafiltration, centrifugation, and
extraction), and the properties of black liquor. This paper is aimed at verifying the
hypothesis that the yield and properties of precipitated lignins depend on concentration of
sulphuric acid used as a precipitating agent. A variety of works related to the study of
methods for the isolation and concentration of by-products from black liquors have been
published (Tejado et al. 2007; Garcia et al. 2009; Toledano et al. 2010a,b; Sun et al.
2011). Different types of mineral and organic acids differing in concentration and
treatments have been considered (Ibrahimet et al. 2004; Garcia et al. 2009; Toledano et
al. 2010a, 2010b; Minu et al. 2012).
Several papers describe a selective precipitation of lignins by a precipitating agent
differing in pH. Isolated lignin for each pH condition was determined and the physico-
chemical properties of the individual lignin fractions registered. Minu et al. (2012) found
that by maintaining a constant pH value, the yield of lignin was higher when using H3PO4
than that obtained by applying H2SO4, HCl, or HNO3. The work of Ibrahim et al. (2004),
however, led to different results, achieving the highest yield using 20% H2SO4. The
difference using various acid concentrations was not, however, significant, reaching only
4% at the 1.4% measuring error. This effect was observed for 20% HCl, HNO3, and
H3PO4. Taking the technological aspects into account, namely variations in composition
of batch pulping, delignification processing, and mode of precipitation, the differences in
the measured values are negligible.
All the mentioned factors may influence the properties of lignin, including the
character and ratio of its functional groups. When using lignin as a biofuel, knowledge of
its composition is not important. When utilizing lignin at a higher level (e.g., as an
antioxidant for rubber blends), such information may be of crucial importance. The
knowledge of the concentration and/or ratio of the individual groups may be used to
optimize the antioxidant activity of lignin and its derivatives. This importance focused
3. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1410
our efforts on characterization of lignin fractions precipitated by H2SO4 with different
initial concentrations of H2SO4, and the subsequent adjustment of the pH to 5, through gel
permeation chromatography (GPC), ultraviolet-visible (UV-VIS) spectroscopy,
nitrobenzene oxidation, and higher heating value determination.
EXPERIMENTAL
Materials
Black liquor (soda-AQ pulping) characterization
The annual plants, hemp and flax, used for obtaining black liquor were kindly
supplied by OP Papírna Ltd. (Olšany, Czech Republic). The cooking conditions: active
alkali sodium hydroxide and the presence of anthraquinone (AQ). The black liquor
obtained had the following characteristics (Table 1): pH of 12.9 ±0.3 (determined by a
digital Jenway (3510 pH-meter, UK) and density 1.242 g/mL (determined by measuring
the mass with the known volume of the black liquor).
Table 1. Characterization of black liquor
Dry matter (wt%) 36.80 ± 0.62
Elemental analysis of black liquor
C (wt%) 36.24 ± 0.09
H (wt%) 4.93 ± 0.05
N(wt%) 1.13 ± 0.01
S(wt%) 0.24 ± 0.04
Ash (wt%) 45.75 ± 0.32
Lignin (wt%)* 21.23 ± 0.64
Carbohydrates (wt%) 33.02
*Klason lignin was determined according to TAPPI T 222 om-02
Lignin recovery from black liquor
The precipitation of lignin from black liquor was initially studied as a single step
process in which a dilute solution of sulphuric acid (5 wt% (1.05 N), 25 wt% (6.01 N), 50
wt% (14.22 N), and 72 wt% (23.99 N)) was added to the black liquor with the pH
adjusted to the desired value at a temperature of 50 °C. Then, 100 mL of the black liquor
was treated with different amounts of diluted acid to obtain a final pH value of 5 while
keeping the temperature constant at 50 °C. After precipitation, the content of each flask
was filtered through a pre-weighed oven-dried filter paper using a vacuum filtration unit.
The precipitated lignin was washed twice with hot water (total volume 400 mL, pH= 6.8)
to remove impurities. The lignin was then dried at 25 °C under a pressure of 0.5 mbar
using lyophilisation equipment (LYOVAC (GT2, Germany) until reaching a constant
weight.
Methods
Lignin analysis
Different techniques were used to establish the physicochemical characteristics of
the obtained lignins.
4. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1411
C, N, H, and S elemental analysis
Total nitrogen (N), carbon (C), hydrogen (H), and sulphur (S) content of all
samples were determined by dry combustion using a Vario Macro Cube C/H/N/S-
analyser (Elementar, Hanau, Germany). Two replicates were measured, and the mean
standard errors were 0.35% for C, 0.04% for N, 0.05% H, and 0.01% for S.
Nitrobenzene oxidation
Oxidation of lignin samples by nitrobenzene was carried out using 2 M NaOH in
10-mL stainless steel vessels at a temperature of 180 °C for 2 h, and oxidation products
were analysed by isocratic high-performance liquid chromatography under the following
conditions: LiChrospher 100 RP-18, 5 μm, 4 × 100 mm ID column (Merck KGaA,
Darmstadt, Germany), mobile phase water:methanol:acetic acid (850:150:1), flow rate of
1.0 mL min-1
, column temperature of 35 °C, and detection via diode array detector in the
210-360-nm region. The quantities of nitrobenzene oxidation products were determined
using the method of direct calibration (Kačík et al. 1995). Measurements were performed
on four replicates per sample. An S/G ratio was calculated using the formula (Eq. 1):
S/G = (syringyl aldehyde + syringic acid) / (vanillin + vanillic acid) (1)
Gel permeation chromatography (GPC)
The molecular weight distribution (MWD) of lignin was measured by GPC using
a Separon Hema S-300 column. The precipitated lignin sample was dissolved in
dimethylformamide (DMF) (5 mg/mL) and the sample was filtered (pore size: 0.45 mm,
material: PTFE) to avoid plugging of the columns from bulky impurities. The
temperature of the column oven was 35 °C, and a volume of 10 µL of each sample was
injected. Lithium bromide (0.005 M) in DMF was used as eluent with a flow rate of 1
mL/min. A differential refractometer (RI) and a diode array detector (DAD) at 280 nm
were used as detectors (Kacik et al. 1992). For calibration, polystyrene samples with
various molecular weights (500 to 98,900) were used. Molecular weight was calculated
from the experimental data using the software Clarity (version 2.3.0.163, Czech
Republic).
Zeta potential of lignin particles
The zeta potential of the lignin particles was determined in water solutions with a
lignin concentration of 10 mg/mL, using a Zetasizer Nano ZS (Malvern Instruments, UK)
at 23 °C. The samples were prepared by dissolving the dry lignin powder. In our study,
zeta potential and electrophoretic mobility were determined at pH 6.6 ± 0.1. To achieve a
good colloidal dispersion, the samples were ultrasound-treated for 10 min at room
temperature prior to the measurements.
UV/VIS spectroscopy
For each type of isolated lignin from black liquor (hemp and flax; modified
alkaline anthraquinone cooking) precipitated by sulphuric acid (5, 25, 50, and 72 wt%), a
stock solution was prepared by dissolving lignin powder (4 mg) in 50 mL of NaOH (0.2
M). The UV-VIS absorption spectra were registered using a solution of lignin on a Cecil
spectrophotometer (Cecil Instruments, UK), absorption region 200 to 450 nm, scan speed
5 nm/s, and 1 nm resolution. Measured values of absorbance were normalized by
absorption maxima at 222 nm.
5. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1412
Difference UV/VIS spectroscopy
After being dried overnight at 80 °C, a precisely weighed amount (5 mg) of lignin
was dissolved in 5 mL of dioxane and 5 mL of 0.2 M NaOH. Some of the solutions were
not quite clear and were filtered using a 0.45-µm PVDF membrane filter. From each
lignin solution, 2 mL was further diluted to 25 mL using either a pH 6 buffer solution
(citrate/NaOH, Merck) or 0.2 M NaOH (Gartner and Gellerstedt 1999). This gave each
solution a final lignin concentration of about 0.04 g/L. The UV-VIS spectra were
recorded on a Cecil spectrophotometer in the absorption region from 200 to 450 nm, scan
speed 5 nm/s, and 1-nm resolution. The lignin solution with pH 6 was used as a
reference, and the alkaline solutions were measured against it. From the difference
spectra, the absorbance values at 300 and 350 nm, measured against the solution
containing 0.2 M NaOH, were recorded. According to the original work of Gartner and
Gellerstedt (1999), six structural types of phenolic structures exist (Fig. 1). Maxima at
300 nm and 350 to 360 nm can be assigned to unconjugated phenolic structures (I and
III), and those at 350 to 370 nm can be assigned to conjugated structures (II and IV).
According to Zakis (1994), the maximum at 360 nm is attributed only to IIa and IVa
types of phenolic structures in lignin.
Fig. 1. Type of phenolic structures determined by the UV method (Zakis 1994; Gartner and
Gellerstedt 1999)
To obtain the concentration of individual phenolic structures in mmol/g, the
following absorbance-based formulae were developed (Zakis 1994; Gartner and
Gellerstedt 1999) and are applied in their original form also in this work (Eqs. 2-4):
a) Non-conjugated phenolic structures (I+III)
OH (I+III) = {(0.250A300nm (NaOH) + 0.0595A350 nm (NaOH)} 1/(cd) (2)
b) Conjugated phenolic structures (II+IV)
OH (II+IV) = {0.0476A350nm (NaOH)} 1/(cd) (3)
c) Total amount of phenolic hydroxyl groups
OH (I+II+III+IV) = {0.250A300nm (NaOH) + 0.107A350 nm (NaOH)} 1/(cd) (4)
6. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1413
where ∆λ is the absorbance at a given wavelength divided by the corresponding molar
absorptivity, c is mass concentration in g/L, and d is path length through the sample in
cm.
Examples of determination of non-conjugated and conjugated phenolic structures are
expressed in Eqs. 5-7.
The data for the sample precipitated lignin with 5 wt% solution of sulphuric acid:
A300nm = 0.230646, A350nm = 0.208924, c = 0.0424 g/L, d = 1.02 cm
a) Non-conjugated phenolic structures (I+III)
OH (I+III) = {(0.250A300nm (NaOH) + 0.0595A350 nm (NaOH)} 1/(cd) (5)
OH (I+III) = {(0.2500.230646 + 0.05950.208924} 1/(0.04241.02)
OH (I+III) = 1.621 mmol/g
b) Conjugated phenolic structures (II+IV)
OH (II+IV) = {0.0476A350nm (NaOH)} 1/(cd) (6)
OH (II+IV) = {0.04760.208924} 1/(0.04241.02)
OH (II+IV) = 0.229 mmol/g
c) Total amount of phenolic hydroxyl groups
OH (I+II+III+IV) = {0.250A300nm (NaOH) + 0.107A350 nm (NaOH)} 1/(cd) (7)
OH (I+II+III+IV) = {0.2500.230646 + 0.1070.208924 1/(0.04241.02)
OH (I+II+III+IV) = 1.850 mmol/g
Higher heating value
Higher heating value (HHV) was determined with a FTT Calorimetric Bomb
(FTT Scientific, UK) using a standard method (Sivaramakrishnan and Ravikumar 2011;
Telmo and Lousada 2011).
Lignin purity determination
Isolated lignin is a raw material containing other substances along with pure
lignin. Polysaccharides as accompanying pollutants were eliminated by a 1 h boiling
treatment in 5 wt% H2SO4. The lignin (%) was determined based on the mass loss at
acidic hydrolysis.
RESULTS AND DISCUSSION
The fractionation process
Some of the results obtained are graphically depicted in Fig. 2, which represents
the lignin precipitation and the properties of the precipitate observed during the treatment
of black liquor from annual plants, such as flax and hemp. Recovery of lignin is
influenced by the concentration of added sulphuric acid. The yields of lignin precipitated
by sulphuric acid were in the range of 9.3 to 10.5 g for every 100 mL of black liquor
used. The concentration of sulphuric acid played a crucial role in this process. The results
indicated that the yield is dependent both on the hydrogen ion concentration in the
solution and the ionic strength. These observations are in agreement with earlier
7. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1414
investigations (Helander et al. 2013). Quantity and purity of isolated lignin are listed in
Table 2. Using 25% H2SO4 as a precipitating agent, the yield of precipitated lignin
reached 9.4 g/100 mL liquor, while with 72 wt% H2SO4, the yield was higher (10.5 g/100
mL liquor) but the purity was lowest (82.4%). This result could be caused by
concentration gradients at sulphuric acid addition, different hydrodynamic conditions, or
a different ionic strength and protonation. Protonation depends on the pKa value of the
lignin structures (Wada et al. 1962; Helander et al. 2013) and reaches about 50%. Using
H2SO4 of a higher concentration, the present lignin-saccharide complexes undergo a local
lower-degree decomposition that is reflected by lower purity of precipitated lignin.
Lignin is precipitated at the same time as sulphuric acid approaches an even distribution
in the system. This is why the purity and yield of the formed lignin cannot be
unambiguously displayed. The most positive of our results in this connection is finding
that the lignin of highest purity is formed when treating the liquor with 25 wt% H2SO4.
Table 2. Purity of isolated fractions of lignin
Precipitated lignin
with solution of sulphuric acid
Purity (%) Yield of pure
lignin (g/100 mL)
5 wt% 85.1 ± 0.2 7.9
25 wt% 92.8 ± 0.1 9.4
50 wt% 90.6 ± 0.4 9.3
72 wt% 82.4 ± 0.4 8.7
0 10 20 30 40 50 60 70 80
0
3
6
9
12
24
27
Arbitraryunits
Ash in precipitate % (w/w)
Calorific value of precipitate (MJ/kg)
Weight of precipitate (g/100 mL)
Concentration of sulphuric acid (%)
Fig. 2. Effect of the concentration of sulphuric acid on the properties of precipitated lignin from the
black liquor of flax and hemp
The use of lignin as a fuel in different applications requires a knowledge of its
heating value. Several studies investigating the heating values of different biomass
species (Demirbas 2003; Vargas-Moreno et al. 2012) and isolated lignins (Minu et al.
2012) have been published. Cellulose and hemicellulose have heating values ranging
from 14.7 to 19.0 to MJ/kg, whereas lignin has values ranging from 22.3 to 27.3 MJ/kg
(Minu et al. 2012). Pure lignin has a rather high heating value, which makes it valuable
for use as a bio-fuel. On average, the heating value of precipitated lignins was 26.5 ±0.3
8. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1415
MJ/kg of dry lignin. This information indicates that the calorific value of precipitated
lignin is independent on the used concentration of acids.
Elemental analysis
The weight percentages of elements C, H, N, O, and S of the isolated precipitate
of lignins are listed in Table 3. The atomic O/C ratios of the isolated lignin were
approximately located between 0.29 and 0.33, and their atomic H/C ratios range from
1.18 to 1.23. The average weight percentage of elements for four samples was C: 64.78 ±
0.87%, H: 6.44 ± 0.09%, N: 1.13 ± 0.03%, S: 0.06 ± 0.01%, and O: 26.79 ± 0.95%. The
results indicate that the lignin elemental composition of is not markedly affected by the
concentration of sulphuric acid. The relatively low content of sulphur required for the
precipitation process makes this biofuel attractive as an additive to fuels.
Table 3. Elemental Analyses and O/C and H/C Atomic Ratios
Precipitated lignin
with solution of sulphuric acid
Elemental analysis (%) H/C O/C
N C H S O
5 wt% 1.11 65.75 6.46 0.06 25.59 1.18 0.29
25 wt% 1.12 63.64 6.54 0.07 26.95 1.23 0.33
50 wt% 1.12 64.84 6.33 0.04 27.96 1.17 0.31
72 wt% 1.18 64.90 6.42 0.07 25.66 1.19 0.31
UV/VIS and Difference UV/VIS spectroscopy
Normalized UV/VIS spectra of preparations are shown in Fig. 3. Free and
etherified hydroxyl groups contribute to the characteristic absorption maximum of lignin
near 280 nm. The lignin fractions showed a characteristic absorption band at 284 nm,
which could be assigned to the non-conjugated phenolic groups of lignin. Absorption
maxima of non-conjugated guaiacyl and 3,4-dimethoxy-phenyl model compounds fall
within the narrow wavelength range from 277 to 282 nm. In an alkaline solution,
ionization of the hydroxyl groups shifts the absorption bands of compounds with free
phenolic groups towards longer wavelengths. Ultraviolet spectroscopy was used to
further investigate the structural components of lignin. The different spectra of alkaline
and neutral solutions of lignins enable interpretation of the chemistry of these substances.
Differential UV-Vis spectroscopy allows the identification of the ionization of phenolic
hydroxyl groups in alkaline solutions while the absorption of etherified lignin units is
unchanged in neutral and alkaline media. Figure 4 shows that all of the precipitated lignin
displayed the characteristic ionisation difference spectra of lignin, with local maximum
intensities centered at 222, 251, 299, and 350 nm; minima were found near 279 and 318
nm.
10. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1417
The content of non-conjugated, conjugated, and total phenolic hydroxyl groups
for these preparations is presented in Table 4. It is known that when lignin is precipitated
from kraft black liquor, the methoxyl content decreases, while the carboxyl and phenolic
hydroxyl contents increase at a lower pH (Wada et al. 1962). Lowering the pH of the
black liquor using different agents (organic or mineral acids, CO2) protonates the
phenolic hydroxyl groups in lignin (Helander et al. 2013). Isolation of lignin,
effectiveness of precipitation, and properties of obtained lignin (the presence and
concentration of individual functional groups) depend both on the precipitation
conditions (temperature, lignin concentration, ionic strength), and lignin protonisation, as
well as acid used (i.e., its acidity constant) (Helander et al. 2013). The content of non-
conjugated phenolic structures (I + III) ranged from 1.03 to 1.67 mmol/g with the
following trend: higher H2SO4 concentration led to lower structural content. The same
trend was found for the total amount of phenolic hydroxyl groups (OH I + II + III + IV).
The content of conjugated phenolic structures (II + IV) was 0.17 to 0.24 mmol/g. The
concentration of H2SO4 thus influenced both the content of individual groups and their
total content. Free and etherified hydroxyl groups contributed to the characteristic
absorption minimum of lignin near 280 nm (difference spectrum). The spectral intensity
at 280 nm was influenced to a substantial extent by the presence of unsaturated
substituents on the -carbon of a side chain (e.g., carbonyl group, double bond). Such
unsaturated groups cause absorption in the near UV region (300 to 400 nm) in the form of
broad peaks or shoulders and thus affect lignin colour (Polčin and Rapson 1969).
Absorption minima of non-conjugated guaiacyl and 3,4-dimethoxy-phenyl model
compounds fall within the narrow wavelength range from 277 to 282 nm. The lignin
absorption at 300 to 400 nm is due to carbonyl groups and/or double bonds conjugated
with an aromatic ring. Evidence for phenolic conjugated α-keto groups was provided by
the difference method. Ionisation difference spectra for certain lignin samples showed a
shoulder or a maximum near 350 nm, which agrees well with the maxima in the spectra
of alkaline solutions of model compounds such as vanillin (λmax= 353 nm). The intense
band near 340 to 350 nm is consistent with the formation of extensive conjugated
structures, such as the Cα=Cβ double bond, β-C=O structure, and the conjugated carbonyl
group in side chains of lignin such as coniferyl aldehyde (Polcin and Rapson 1969). The
peak centered at 355 nm in the ∆A spectrum of the preparations was composed of peaks
due to p,p-dihydroxystilbenes (λmax = 356 nm) and phenolic α-carbonyl units (λmax > 350
nm).
Electrokinetic properties
A knowledge of the electrokinetic properties of lignin is therefore of fundamental
and practical importance. Zeta potential of lignin solutions shows that charge of lignin
colloid can be an indicator of the tendency for the colloid to precipitate (Table 5)
(Rudatin et al. 1989; Wang and Chen 2013). Dong et al. (1996) found that the pH
strongly affects the zeta potential of kraft lignin. In our study, zeta potential and
electrophoretic mobility at pH 6.6 ±0.1 were determined. The highest value of
electrophoretic mobility (-1.62 ±0.04 µmcm/Vs) and zeta potential (-20.64 ±0.53 mV)
were determined for lignin precipitated by 5 wt% H2SO4. Applying acid of a higher
concentration reduced both the electrophoretic mobility and zeta potential (Table 4). The
differences in both the electrophoretic mobility and zeta potential may result from the
fact that even at the same final pH value the nature of charge distribution reflects a mode
11. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1418
of solution formation. This issue will be treated in detail elsewhere. Different separation
procedures may result in different functionality or different functional group on the
surface of lignin. Zeta potential is important in the air flotation of slurry waste water. In
this case, the zeta potential and electrophoretic mobility of the lignin particles decreased
from -20.64 mV and -1.62 μm cm/Vs (sample 5 wt%) to -17.54 mV and -1.37 μm cm/Vs
(25 wt%). This may indicate strengthening of the association/aggregation interactions,
leading to the formation of lignin particles with less charge and larger in size. It follows
from the zeta potential and electrophoretic mobility values that the lignin precipitated
with 25 wt% sulphuric acid exhibited the highest yield of pure lignin.
Table 5. Zeta potential and electrophoretic mobility of lignin particles in lignin
aqueous solution, pH 6.6 ±0.1
Precipitated lignin
with solution of sulphuric acid
Zeta
potential,
(mV)
Standard
deviation,
(mV)
Electrophoretic
mobility,
(µmcm/Vs)
Standard
deviation,
(µmcm/Vs)
5 wt% -20.64 0.53 -1.62 0.04
25 wt% -17.54 0.52 -1.37 0.04
50 wt% -18.30 1.19 -1.43 0.09
72 wt% -18.42 0.39 -1.44 0.03
Nitrobenzene oxidation
Nitrobenzene oxidation is one of the standard procedures for analysing lignin by
the chemical degradation technique to gain information about the composition of the
original polymer. The composition of the three monomeric lignin units, p-hydroxyphenyl
(H), guaiacyl (G), and syringyl (S), which are capable of producing degradation products
such as vanillin, vanillic acid, syringaldehyde, syringic acid, p-hydroxylbenzadehyde, and
p-hydroxybenzoic acid, were analysed, and the results are shown in Tables 6a and 6b.
Vanillin was found to be the predominant compound followed by syringaldehyde as a
second major degradation product. The total yield of the oxidation products ranged from
6.64% to 6.76%. The presence of a lesser amount of p-hydroxybenzaldehyde and p-
hydroxybenzoic acid is considered most likely to be indicative of non-condensed p-
hydroxyphenyl units. H:G:S ratios were also calculated for precipitated lignins. The
results are displayed in Table 7. The values of the G-units for lignin samples were above
63%. The values for S-units and H-units of precipitated lignin samples were in the range
of 25.2 to 28.1% and 7.4 to 8.8%, respectively. For precipitated lignin samples, the ratio
of G:S:H was 7 to 9:3 to 2:1 which fell in the same category as straw or grass type lignin
(Scalbert and Monties 1986; Ibrahim et al. 2004).
Table 5a. Yield of degradation products of the precipitated lignin samples by
nitrobenzene oxidation
Precipitated lignin
with solution of sulphuric acid
Vanillin Vanillic acid Syringaldehyde Syringic acid
(%)
AVG SD AVG SD AVG SD AVG SD
5 wt% 3.217 0.005 1.072 0.003 1.481 0.003 0.456 0.002
25 wt% 3.236 0.003 1.021 0.007 1.504 0.007 0.449 0.003
50 wt% 3.199 0.012 1.005 0.006 1.438 0.017 0.438 0.004
72 wt% 3.204 0.071 0.881 0.026 1.680 0.098 0.498 0.040
12. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1419
Table 5b. Yield of degradation products of the precipitated lignin samples by
nitrobenzene oxidation
Precipitated lignin
with solution of sulphuric acid
p-hydroxybenzaldehyde p-hydroxybenzoic acid Total (Yield) %
(%)
AVG SD AVG SD AVG SD
5 wt% 0.057 0.001 0.352 0.003 6.635 0.010
25 wt% 0.074 0.001 0.373 0.006 6.658 0.017
50 wt% 0.067 0.002 0.333 0.002 6.480 0.044
72 wt% 0.072 0.007 0.424 0.006 6.760 0.235
Molecular weight
The molecular weight distributions (MWDs) of the four investigated precipitated
lignins are presented in Fig. 5. From the GPC results, the weight-average (Mw), number-
average (Mn), and polydispersity (Mw/Mn) values were calculated and are shown in
Table 6. Lignin isolated by sulphuric acid (concentration 5 wt%, 25 wt%, 50 wt%, and 72
wt%), showed no significant difference in Mw, ranging from 9367 to 9823. In general,
the distribution curves of lignin preparations present reasonably symmetrical peaks,
whereas those of lignin fractions are asymmetric to a greater or lesser degree, dependent
on the type of fractionation. It is obvious that there is a connection between the lignin and
polysaccharide fractions (Zoia et al. 2011). All of the samples showed a bimodal
molecular weight distribution. On the other hand it is known that some association
processes due to different lignin branching and cross-linking can occur influencing the
shape of distribution curve (Cathala et al. 2003). Such associations may result from
random distribution of OH, CO, and COOH groups in lignin and their mutual
interactions, e.g., by van der Waals forces, due to ionisation of the groups and formation
of intermediates of lignin oxidation (Bikova et al. 2004). As pointed out by Guerra et al.
(2007), an unambiguous correlation of the groups’ content and their ionisation is not
statistically proven. It should be stressed that, here, polysaccharide-containing lignins,
i.e., raw lignin, were isolated and investigated (Tables 1 and 7). The yield of pure lignin
ranged from 7.9 to 9.4 g/mL; the higher value was reached at precipitation by 25 wt%
H2SO4. Our results are in accordance with those published by Ibrahim et al. (2004) who
realized the highest yield of lignin using 20 wt% sulphuric, hydrochloric, phosphoric or
nitric acid. Ibrahim et al. (2004) ascribed this fact to localised acidification or a non-
uniform precipitation effect when high acid concentrations were used.
13. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1420
1 2 3 4 5
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
dW/dlogM
log M
precipitate lignin 5 % H2SO4
precipitate lignin 25 % H2SO4
precipitate lignin 50 % H2SO4
precipitate lignin 72 % H2SO4
Fig. 5. GPC chromatograms of different preparations obtained by acid precipitation using
sulphuric acid of different concentrations
Table 6. Molar Ratio of Degradation Products of the Precipitated Lignin Samples
by Nitrobenzene Oxidation and Molecular Weights and Polydispersity of the
Lignin Fractions
Precipitated lignin
with solution of
sulphuric acid
G S H Mn Mw Mz Mz+1 Mw/Mn
5 wt%
67.2 25.5 7.4
AVG 478 9823 41451 74653 20.56
SD 8.49 24.75 232.64 589.02 0.39
RSD 1.78 0.25 0.56 0.79 1.91
25 wt% 66.4 25.6 8.0
AVG 455 9440 40483 73036 20.76
SD 2.12 29.70 85.56 116.67 0.04
RSD 0.47 0.31 0.21 0.16 0.19
50 wt% 67.4 25.2 7.4
AVG 458 9367 40533 73136 20.46
SD 5.66 31.82 178.19 311.13 0.31
RSD 1.24 0.34 0.44 0.43 1.50
72 wt% 63.1 28.1 8.8
AVG 480 9593 42427 77395 20.01
SD 15.56 130.81 1489.17 4010.00 0.90
RSD 3.24 1.36 3.51 5.18 4.50
Note: Mn = number-average molecular weight, Mw = weight-average molecular weights,
Mz = Z-average molecular weight, Mz+1 = Z+1 average molecular weight (Mz+1),
(Mw/Mn) = polydispersity
CONCLUSIONS
1. According to the distinct acid precipitation behaviors, fractionation of lignin with
various concentrations of sulphuric acid (5 wt%, 20 wt%, 50 wt%, and 72 wt%) at pH
5 was established in this study. Physicochemical and surface characterization of
14. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1421
precipitated lignin samples was performed. There were clear differences between the
precipitates obtained at pH 5 with differing concentrations of sulphuric acid,
especially considering the content and properties of obtained lignin, such as the
content of non-conjugated, conjugated, and total phenolic hydroxyl groups.
2. The acid concentration influenced the yield of precipitated lignin. The concentration
of acid had an effect on the electrokinetic properties of solutions containing
precipitated lignin. The zeta potential and electrophoretic mobility for the lignin
precipitated with 25 wt% sulphuric acid exhibited the highest yield of pure lignin.
However, the concentration of this acid did not have an effect on the elemental
composition and on the higher heating value of precipitated lignin.
ACKNOWLEDGMENTS
We are very grateful to Dr. Shabaz Mohammed from the University of Oxford for
critical reading of the manuscript. This article was created with the support of the
Ministry of Education, Science, Research and Sport of the Slovak Republic within the
Research and Development Operational Program for the project “University Science Park
of STU Bratislava”, ITMS 26240220084, co-funded by the European Regional
Development Fund and National Center for Research and Application of Renewable
Energy Sources, ITMS: 26240120016, supported by the Research & Development
Operational Program funded by the ERDF and Finalization of Infrastructure of the
National Center for Research and Application of Renewable Energy Sources (ITMS:
26240120028). This publication was supported through the projects APVV-0850-11,
VEGA 1/0985/12 and VEGA 1/0775/13.
REFERENCES CITED
Bikova, T., Treimanis, A., Rossinska, G., and Telysheva, G. (2004). “On-line study of
lignin behaviour in dilute alkaline solution by the size exclusion chromatography
(SEC)-UV method,” Holzforschung 58(5), 489-494. DOI: 10.1515/HF.2004.074
Cathala, B., Saake, B., Faix, O., and Monties, B. (2003). “Association behaviour of
lignins and lignin model compounds studied by multidetector size exclusion
chromatography,” J. Chromatogr. A. 1020(2), 229-239. DOI:
10.1016/j.chroma.2003.08.046
Demirbas, A. (2003). “Relationships between lignin contents and fixed carbon contents
of biomass samples,” Energy Convers. Manage. 44(9), 1481-1486. DOI:
10.1016/S0196-8904(02)00168-1
Dong, D., Fricke, A. L., Moudgil, B. M., and Johnson, H. (1996). “Electrokinetic study of
kraft lignin,” TAPPI J. 79(7), 191-197.
Garcia, A., Toledano, A., Serrano, L., Egues, I., Gonzalez, M., Marin, F., and Labidi, J.
(2009). “Characterization of lignins obtained by selective precipitation,” Sep. Pur.
Tech. 68(2), 193-198. DOI: 10.1016/j.seppur.2009.05.001
Gartner, A., and Gellerstedt, G. (1999). “Determination of phenolic hydroxyl groups in
residual lignin using a modified UV-method,” Nord. Pulp Pap. Res. J. 14(2), 163-
170. DOI: 10.3183/NPPRJ-1999-14-02-p163-170
15. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1422
Gosselink, R. J. A., Abächerli, A., Semke, H., Malherbe, R., Käuper, P., Nadif, A., and
van Dam, J. E. G. (2004). “Analytical protocols for characterisation of sulphur-free
lignin,” Industrial Crops and Products, 19(3), 271-281. DOI:
10.1016/j.indcrop.2003.10.008
Guerra, A., Gaspar, A. R., Contreras, S., Lucia, L. A., Crestini, C., and Argyropoulos, D.
S. (2007). “On the propensity of lignin to associate: A size exclusion chromatography
study with lignin derivatives isolated from different plant species,” Phytochemistry
68(20), 2570-2583. DOI: 10.1016/j.phytochem.2007.05.026
Helander, M., Theliander, H., Lawoko, M., Henriksson, G., Zhang, L., and Lindstrom, M.
E. (2013). “Fractionation of technical lignin: Molecular mass and pH effects,”
BioRes. 8(2), 2270-2282. DOI: 10.15376/biores.8.2.2270-2282
Holladay, J. E., White, J. F., Bozell, J. J., and Johnson, D. (2007). Top Value-Added
Chemicals from Biomass. Volume II-Results of Screening for Potential. DOE Report
number PNNL-16983, Pacific Northwest National Laboratory, Richland, WA
(www.pnl.gov/main/publications/external/technical_reports/PNNL-16983.pdf).
Ibrahim, M. M. N., Chuah, S. B., and Rosli, W. D. W. (2004). “Characterization of lignin
precipitated from the soda black liquor of oil palm empty fruit bunch fibers by
various mineral acids,” AJSTD 21(1), 57-67.
Kacik, F., Solar, R., and Melcer, I. (1992). “Gel permeation chromatography of lignins on
the Separon HEMA columns,” Drev. Vyskum 135, 39-48.
Kacik, F., Solar, R., and Baloghova, D. (1995). “Analysis of lignin nitrobenzene
oxidation products by high performance liquid chromatography (HPLC),” Drev.
Vyskum 40(3), 13-20.
Minu, K., Kurian Jiby, K., and Kishore, V. V. N. (2012). “Isolation and purification of
lignin and silica from the black liquor generated during the production of bioethanol
from rice straw,” Biomass Bioenerg. 39(SI), 210-217. DOI:
10.1016/j.biombioe.2012.01.007
Mosier, N., Hendrickson, R., Ho, N., Sedlak, M., and Ladisch, M. R. (2005).
“Optimization of pH controlled liquid hot water pretreatment of corn stover,”
Bioresour. Technol. 96(18), 1986-1993. DOI: 10.1016/j.biortech.2005.01.013
Polcin, J., and Rapson, W. H. (1969). “Spektrophotometrische untersuchung von holz-
chromophoren in situ. II. Bestimmung des absorptions spektrums von lignin aus
reflexionsmessungen,” TAPPI J. 52(10), 1965-1970.
Rosas, J. M., Berenguer, R., Valero-Romero, J. M., Rodríguez-Mirasol, J. Cordero, T.
(2014). “Preparation of different carbon materials by thermochemical conversion of
lignin,” Front. Mater. 1(29), 1-17. DOI: 10.3389/fmats.2014.00029
Rudatin, S., Sen, Y. L., and Woerner, D. L. (1989). “Association of kraft lignin in
aqueous-solution,” ACS Sym. Ser. 397, 145-154. DOI: 10.1021/bk-1989-0397.ch011
Scalbert, A., and Monties, B. (1986). “Comparison of wheat straw lignin preparations. 2.
Straw lignin solubilisation in alkali,” Holzforchung 40(4), 249-254. DOI:
10.1515/hfsg.1986.40.4.249
Sivaramakrishnan, K., and Ravikumar P. (2011). “Determination of higher heating value
of biodiesels,” Int. J. Eng. Sci. Technol. 3(11), 7981-7987.
Sun, N., Rodriguez, H., Rahman, M., and Rogers, R. D. (2011). “Where are ionic liquid
strategies most suited in the pursuit of chemicals and energy from lignocellulosic
biomass?,” Chem. Commun. 47(5), 1405-1421. DOI: 10.1039/c0cc03990j
Sun, S. N., Li, M. F., Yuan, T. Q., Xu, F., and Sun, R. C. (2013). “Effect of ionic
liquid/organic solvent pretreatment on the enzymatic hydrolysis of corncob for
16. PEER-REVIEWED ARTICLE bioresources.com
Surina et al. (2015). “Characterisation of lignins,” BioResources 10(1), 1408-1423. 1423
bioethanol production. Part 1: Structural characterization of the lignins,” Ind. Crop.
Prod. 43, 570-577. DOI: 10.1016/j.indcrop.2012.07.074
Tejado, A., Peňa, C., Labidi, J., Echevérria, J. M., and Mondragon, I. (2007). “Physico
chemical characterization of lignins from different sources for use in phenol-
formaldehyde resin synthesis,” Bioresour. Technol. 98(8), 1655-1663. DOI:
10.1016/j.biortech.2006.05.042
Telmo, C., and Lousada, J. (2011). “The explained variation by lignin and extractive
contents on higher heating value of wood,” Biomass Bioenerg. 35(5), 1663-1667.
DOI: 10.1016/j.biombioe.2010.12.038
Toledano, A., García, A., Mondragon, I., and Labidi, J. (2010a). “Lignin separation and
fractionation by ultrafiltration,” Sep. Pur. Tech. 71(1), 38-43. DOI:
10.1016/j.seppur.2009.10.024
Toledano, A., Serrano, L., Garcia, A., Mondragon, I., and Labidi, J. (2010b).
“Comparative study of lignin fractionation by ultrafiltration and selective
precipitation,” Chem. Eng. J. 157(1), 93-99. DOI: 10.1016/j.cej.2009.10.056
Vargas-Moreno, J. M., Callejon-Ferre, A. J., Perez-Alonso, J., and Velazquez-Marti, B.
(2012). “A review of the mathematical models for predicting the heating value of
biomass materials,” Renew. Sust. Energy Rev. 16(5), 3065-3083. DOI:
10.1016/j.rser.2012.02.054
Vishtal, A., and Kraslawski, A. (2011). “Challenges of industrial application of technical
lignins,” BioRes. 6(3), 3547-3568. DOI: 10.15376/biores.6.3.3547-3568
Wada, S., Iwamida, T., Iizima, R., and Yabe, K. (1962). “Fractional precipitation of kraft
black liquor from spruce wood,” Kabunshi Kagaku 19, 699-703. DOI:
10.1295/koron1944.19.699
Wang, G., and Chen, H. (2013). “Fractionation of alkali-extracted lignin from steam-
exploded stalk by gradient acid precipitation,” Sep. Pur. Technol. 105, 98-105. DOI:
10.1016/j.seppur.2012.12.009
Zakis, G. F. (1994). Functional Analysis of Lignins and their Derivatives, TAPPI Press,
Atlanta, GA.
Zakzeski, J., Bruijnincx, P. C. A., Jongerius, A. L., and Weckhuysen, B. M. (2010). “The
catalytic valorization of lignin for the production of renewable chemicals,” Chem.
Rev. 110(6), 3552-3559. DOI: 10.1021/cr900354u
Zoia, L., King, A. W. T., and Argyropoulos, D. S. (2011). “Molecular weight
distributions and linkages in lignocellulosic materials derivatized from ionic liquid
media,” J. Agric. Food Chem. 59(3), 829-838. DOI: 10.1021/jf103615e
Article submitted: July 2, 2014; Peer review completed: October 19, 2014; Revised
version accepted: January 7, 2015; Published: January 13, 2015.