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.
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.
REVIEW OF BOILING TO POOL BOILING HEAT TRANSFER USING NANOFLUIDIJESM JOURNAL
Nanofluids are a new class of heat transfer fluids developed by suspending nanosized solid particles in liquids. Larger thermal conductivities of solid particles compared to the base fluids such as water, ethylene glycol, engine oil etc. significantly enhances their thermal properties. Several phenomenological models have been proposed to explain the anomalous heat transfer enhancement in nanofluids. This paper presents a systematic literature review to exploit the boiling heat transfer enhancements using different compositions of Nanofluids used experimentally also attempts are made to make systematic analysis of results in literature and try to bring out a common understanding of the results in literature.
This review article summarizes recent progress in researching nanofluids, which are liquids containing nanoscale solid particles. Nanofluids show potential for enhanced heat transfer applications. The article discusses nanofluid fabrication methods, evaluation of stability over time, procedures to improve stability, analysis of thermophysical properties, and challenges to commercialization. It identifies opportunities for future work to bridge the gap between laboratory research and real-world application of nanofluids, such as understanding nanofluid behavior and stability under operating conditions.
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.
THERMAL CONDUCTIVITY OF NANOFLUIDS PREPARED FROM BIOBASED NANOMATERIALS DISPE...IAEME Publication
In the present study, experimental investigation on thermal conductivity of green
nanofluids prepared from coconut fibre-based nanoparticles and suspended in 60:40
ethylene glycol (EG) water (W) mixture was carried out. The measurement of thermal
conductivity was conducted at 15 °C to 60 °C at mass fractions of 0.04 wt%, 0.08
wt%, 0.5 wt% and 1 wt%. The results show deterioration in thermal conductivity with
an increasing temperature. Also the deterioration increased as the mass fraction
increased.
This document summarizes a study that investigated heat transfer in a plate heat exchanger using water-based TiO2 nanofluids. Two different weight fractions (0.1% and 0.5%) of TiO2 nanofluids were prepared and their heat transfer performance was experimentally tested in the plate heat exchanger. The results showed that the 0.5% nanofluid provided significant enhancement of the overall heat transfer coefficient at higher Reynolds numbers compared to water, while the 0.1% nanofluid showed a decrease compared to water.
Preparation of pyrimido[4,5 b][1,6]naphthyridin-4(1 h)-one derivativeselshimaa eid
This document describes the preparation of pyrimido[4,5-b][1,6]naphthyridin-4(1H)-one derivatives using a zeolite-nanogold catalyst. An efficient one-pot synthesis is developed involving the cyclocondensation of 6-amino-2-thioxo-2,3-dihydropyrimidin-4(1H)-one, aromatic aldehydes, and 1-benzylpiperidin-4-one in ethanol at 80°C. The nanogold catalyst is characterized and found to contain 4-6 nm gold nanoparticles dispersed on zeolite. Several derivatives are synthesized in good yields and characterized. Molecular dock
This project is been done to evaluate the tolerence level of the different trees species to air pollution w.r.t 4 different parameters i.e Total Chlorophyll (TCh), pH of the leaf extract, Relative Water Content (RWC) & AIR POLLUTION TOLRENCE INDEX (APTI) and further more.
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.
REVIEW OF BOILING TO POOL BOILING HEAT TRANSFER USING NANOFLUIDIJESM JOURNAL
Nanofluids are a new class of heat transfer fluids developed by suspending nanosized solid particles in liquids. Larger thermal conductivities of solid particles compared to the base fluids such as water, ethylene glycol, engine oil etc. significantly enhances their thermal properties. Several phenomenological models have been proposed to explain the anomalous heat transfer enhancement in nanofluids. This paper presents a systematic literature review to exploit the boiling heat transfer enhancements using different compositions of Nanofluids used experimentally also attempts are made to make systematic analysis of results in literature and try to bring out a common understanding of the results in literature.
This review article summarizes recent progress in researching nanofluids, which are liquids containing nanoscale solid particles. Nanofluids show potential for enhanced heat transfer applications. The article discusses nanofluid fabrication methods, evaluation of stability over time, procedures to improve stability, analysis of thermophysical properties, and challenges to commercialization. It identifies opportunities for future work to bridge the gap between laboratory research and real-world application of nanofluids, such as understanding nanofluid behavior and stability under operating conditions.
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.
THERMAL CONDUCTIVITY OF NANOFLUIDS PREPARED FROM BIOBASED NANOMATERIALS DISPE...IAEME Publication
In the present study, experimental investigation on thermal conductivity of green
nanofluids prepared from coconut fibre-based nanoparticles and suspended in 60:40
ethylene glycol (EG) water (W) mixture was carried out. The measurement of thermal
conductivity was conducted at 15 °C to 60 °C at mass fractions of 0.04 wt%, 0.08
wt%, 0.5 wt% and 1 wt%. The results show deterioration in thermal conductivity with
an increasing temperature. Also the deterioration increased as the mass fraction
increased.
This document summarizes a study that investigated heat transfer in a plate heat exchanger using water-based TiO2 nanofluids. Two different weight fractions (0.1% and 0.5%) of TiO2 nanofluids were prepared and their heat transfer performance was experimentally tested in the plate heat exchanger. The results showed that the 0.5% nanofluid provided significant enhancement of the overall heat transfer coefficient at higher Reynolds numbers compared to water, while the 0.1% nanofluid showed a decrease compared to water.
Preparation of pyrimido[4,5 b][1,6]naphthyridin-4(1 h)-one derivativeselshimaa eid
This document describes the preparation of pyrimido[4,5-b][1,6]naphthyridin-4(1H)-one derivatives using a zeolite-nanogold catalyst. An efficient one-pot synthesis is developed involving the cyclocondensation of 6-amino-2-thioxo-2,3-dihydropyrimidin-4(1H)-one, aromatic aldehydes, and 1-benzylpiperidin-4-one in ethanol at 80°C. The nanogold catalyst is characterized and found to contain 4-6 nm gold nanoparticles dispersed on zeolite. Several derivatives are synthesized in good yields and characterized. Molecular dock
This project is been done to evaluate the tolerence level of the different trees species to air pollution w.r.t 4 different parameters i.e Total Chlorophyll (TCh), pH of the leaf extract, Relative Water Content (RWC) & AIR POLLUTION TOLRENCE INDEX (APTI) and further more.
Discussion about hydrothermal & gel growth method of crystalMostakimRahman1
1.Definition, procedure, advantage, and disadvantage of hydrothermal growth method of crystal.
2.Definition, procedure, advantage, and disadvantage of gel growth method of crystal.
The International Journal of Engineering and Science (IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This document describes a study that examined the factors influencing the effectiveness of hydrogen peroxide vapor for surface decontamination. The study tested different combinations of hydrogen peroxide concentration (400, 600, 800 ppm) and humidity levels on test surfaces inoculated with Geobacillus stearothermophilus spores. The results showed that higher hydrogen peroxide concentrations and higher humidity levels resulted in faster spore inactivation. Subvisible condensation enhanced inactivation, but visible condensation provided no further benefit. The deposition of water and hydrogen peroxide on surfaces, not gas phase concentration, was found to be the determining factor for microbial inactivation.
Gravimetric, mechanical and chemical characterization of different materials used in sewers systems: Polyvinyl chloride (PVC), polypropylene (PP) and high density polyethylene (HDPE), aged in sulfuric acid at 60°C
This document discusses primary and secondary standards used in pharmaceutical analysis. Primary standards are highly pure substances (99.95-100.05%) that are stable over temperature and used to standardize volumetric reagents. They must be easy to obtain and purify, soluble, and react stoichiometrically. Examples include potassium hydrogen phthalate and sodium carbonate. Secondary standards are solutions of known concentration determined by titrating against a primary standard. They have less purity and stability than primary standards and are used when primary standards are not practical, such as sodium hydroxide and potassium permanganate.
Optimizing the Reverse Osmosis Process Parameters by Maximizing Recovery by T...QUESTJOURNAL
ABSTRACT: In this study, the effects of Operating Pressure, Potential Hydrogen, Oxidation Reduction Potential and Anti Scaling Agent on multi responses like Permeate, COD, Total Solids, Conductivity and Hardness in the Reverse Osmosis Process were experimentally investigated on RO 8100 ST8 PT44 400Wl machine. The settings of RO parameters were determined by using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) are employed to find the optimal levels and to analyze the effect of the RO parameters. Results show that potential of hydrogen, operating pressure, oxidation reduction potential and anti scaling agent are the four Parameters that influence the Permit more effectively and COD, Total Solids, Conductivity and Hardness respectively. Improvement in recovery of RO process is achieved with optimize setting. Finally, the ranges for best RO conditions are proposed for ZLD process.
E.G. Sreenivasula Reddy is seeking a position that utilizes his experience in analytical method development and validation for pesticides and chemicals. He holds an M.Sc. in Organic Chemistry and has over 10 years of experience in GLP certified laboratories developing and validating HPLC and GC methods. His responsibilities included residue analysis, environmental fate studies, and shelf-life testing. He is proficient in MS Office, knowledgeable in computer skills and instrumentation such as HPLC, GC, and FT-IR.
E.G. Sreenivasula Reddy is applying for positions with his resume. He has a M.Sc. in Organic Chemistry and experience working as a scientist and study director in GLP laboratories for various companies. His responsibilities included analytical method development, validations, residue analysis, and physicochemical property testing. He is proficient in MS Office and various analytical instruments. He has published 10 papers and presented at conferences. Reddy is looking for opportunities where he can contribute as a team member through hard work, dedication, and positive thinking.
Comprehensive Review of the Investigation of Anthropogenic and Naturally Occu...IJAEMSJORNAL
Authors attempt to depict a survey of anthropogenic 137Cs and naturally occurring radionuclides (226Ra, 228Th, 232Th, 214Bi, 208TI, 40K) in undistributed soil, water, ship scrapped materials such as metal, rubber and foam and tree bark of ship breaking area, cynoglossids i.e. tongue soles and tea leaves collected from different parts of Bangladesh for detecting health hazards, environmental protection and radiation safety of the public. The assessment of such radionuclides in these samples is utmost important due to nuclear test and accident, fallout and disposal of radioactive wastes. These radiotracers have been investigated by using laboratory-based Gamma Spectrometry for Food and Environmental Samples. The observation of activity concentrations for 137Cs, 226Ra, 228Th,232Th, 214Bi, 208TI and 40K have been presented in Bq.Kg-1. The others radiological parameters such as gamma ray dose rate (nGyh-1), Radium Equivalent Dose (Raeq) Bq.Kg-1, Representative Level Index (lr) Bq.Kg-1 and Transfer Factor (TF) %. The Radiation Hazard Index (Hx) Bq.Kg-1 also has been presented.
This document describes a dissertation that examines palladium-catalyzed Heck and Heck/Suzuki domino reactions, as well as applications of microwave heating technology in continuous flow organic synthesis. Specifically, the dissertation includes studies on: 1) developing a ligand-modulated approach to selectively attach aryl groups to a chelating vinyl ether, 2) evaluating a novel microwave applicator for heating solvents and reaction mixtures in continuous flow, 3) developing regioselective oxidative decarboxylative Heck reactions of electron-rich olefins, and 4) a theoretical mechanistic investigation of one such decarboxylative Heck reaction.
Study of Properties of Nanofluids and its EffectIRJET Journal
This document summarizes research on using nanofluids to enhance heat transfer in car radiators. It reviews studies that have shown nanofluids can increase the thermal conductivity and heat transfer coefficient of the coolant in radiators. Several key findings are discussed:
1) Adding nanoparticles like Al2O3 or CuO to the coolant increases the heat transfer coefficient and improves the cooling performance of the radiator.
2) Heat transfer is enhanced by up to 94% with 10% Al2O3 nanofluid and 89% with 6% CuO nanofluid.
3) For the same level of heat transfer, nanofluids reduce the pumping power required compared to the base fluid.
Synthesis and Characterization of Cationic Surfactants Based (1)Nesreen A. Fatthallah
1) The document describes the synthesis and characterization of four cationic surfactants based on N-hexamethylenetetramine and alkyl chlorides.
2) The surfactants were tested for their antimicrobial activity against four bacterial strains. The maximum activity was observed for N-hexamethylenetetramine-N-ethyl silane ammonium trichloride (Ah) which showed 73% inhibition of Staphylococcus aureus.
3) Surface tension measurements were performed to determine properties like critical micelle concentration and thermodynamic parameters of adsorption and micellization. Fourier transform infrared spectroscopy and mass spectrometry were used to characterize the synthesized surfactants.
Synthesis and Characterization of Hydroxyapatite/Graphene Oxide for Biomedica...IRJET Journal
This document summarizes a study that synthesized hydroxyapatite/graphene oxide composite for biomedical applications. Graphene oxide was first synthesized using a modified Hummers' method and hydroxyapatite/graphene oxide composite was prepared via co-precipitation. The composite was characterized using various techniques. XRD and FTIR confirmed the presence of hydroxyapatite and graphene oxide in the composite. SEM images showed the composite had a uniform morphology. The composite also demonstrated antibacterial properties against both gram-positive and gram-negative bacteria, indicating its potential for use in biomedical applications.
The synthesis of 1,4-dihydropyridines was performed in a continuous-flow microreactor. Elevated
temperatures accelerated the reaction rate significantly allowing the reaction to be finished in minutes
(6–11 min). Different 1,4-dihydropyridines were prepared in good to excellent isolated yields (45–88%
yield). The method was amenable to the preparation of daropidine, a calcium channel blocker which is
currently in clinical phase 3 trials.
The document summarizes the services provided by Golder Associates Research Laboratory (GARL), which includes conducting toxicity tests, analytical studies, and soil studies to evaluate the environmental impacts of contaminants. GARL uses standard testing techniques to measure the effects of substances discharged into the aquatic and terrestrial environment. They also work with other divisions at Golder to take an integrated scientific approach in areas like risk assessment, treatment processes, and monitoring programs. GARL is SANAS 17025 accredited and able to perform a wide range of analyses to assist clients across sectors like mining, oil and gas, manufacturing, and more.
Sodium Hypophosphite: An Efficient Catalyst for Synthesis of PyranopyrazolesIJSRED
This document summarizes research on using sodium hypophosphite as an efficient catalyst for the synthesis of pyranopyrazoles. A one-pot four component reaction is carried out with aldehydes, ethyl acetoacetate, hydrazine hydrate, and malononitrile in the presence of the sodium hypophosphite catalyst at room temperature. This protocol provides short reaction times, high yields, easy purification, and uses an economically available catalyst. Various pyranopyrazoles are synthesized with different aldehydes, and their melting points and spectral data are reported. Sodium hypophosphite is found to accelerate the reaction and provide a green, environmentally friendly synthesis method
Investigation of Metal and Chemical Hydrides for Hydrogen Storage in Novel Fu...chrisrobschu
DOE Funded Activities
Objectives:
•Use engineering analyses to screen H2 storage systems against DoD targets & requirements (FY15)
•Identify suitable hydrogen storage materials and suitable vehicle demonstration platforms
•Develop a preliminary design of an integrated UUV design with a solid hydrogen storage system
•Complete detailed design of the hydrogen storage system
•Complete integrated system design
ONR/NUWC Funded Activities
Objectives:
•
Design and build a small bench-scale, alane-based, hydrogen storage vessel
•
Perform preliminary testing on the bench-scale, storage system
•
Package and ship bench-scale vessel and alanematerial to the Navy NUWC
•
Provide technical support to Navy NUWC for their further testing and evaluation
Doe amr st134_motyka_2016_p
This document is a thesis submitted by Bh. Koti Reddy for the award of a Doctor of Philosophy (Engineering) degree from Jadavpur University, Kolkata. The thesis investigates the consolidation behavior of organic clays found in the Kolkata region of India. It includes laboratory testing of undisturbed soil samples collected from various locations to determine their index properties, microstructure, mineralogy, and classification. Both incremental loading (IL) consolidation tests and constant rate of strain (CRS) consolidation tests are conducted to study the consolidation behavior and parameters of the organic clays. The effects of organic content, strain rate, and loading duration are also evaluated. The thesis provides valuable data on the characterization and consolidation behavior
Modeling of variable speed compressor vapour compression refrigeration system...Husain Mehdi
Lots of researches have been done and going on based on the performance evaluation of various metallic/ nonmetallic nanoparticle suspended into the conventional fluid to enhance the heat transfer property of base fluid. Also some theoretical analysis of suspension of nanoparticle Al2O3 in conventional refrigerant. On the other hand the performance of vapour compression cycle based chiller facility using nano refrigerant yet to be analyzed with different type, concentration and diameter of nanoparticle. Such as TiO2, CuO nanoparticle suspension into conventional refrigerant with different concentration and diameter have been analyzed by several investigators and also effect of variation of concentration and nanoparticle diameter on the first and second law performance of vapour compression refrigeration system is presented. The effect of changing input parameter of VCRS using nano refrigerant also affecting significantly the evaporative heat transfer coefficient and very little condor heat transfer coefficient. The idea of Suspension nanoparticle into conventional refrigerant and theoretical analysis of VCRS using nano-refrigerant is proposed after going through extensive literature review presented in this paper.
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.
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.
Discussion about hydrothermal & gel growth method of crystalMostakimRahman1
1.Definition, procedure, advantage, and disadvantage of hydrothermal growth method of crystal.
2.Definition, procedure, advantage, and disadvantage of gel growth method of crystal.
The International Journal of Engineering and Science (IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This document describes a study that examined the factors influencing the effectiveness of hydrogen peroxide vapor for surface decontamination. The study tested different combinations of hydrogen peroxide concentration (400, 600, 800 ppm) and humidity levels on test surfaces inoculated with Geobacillus stearothermophilus spores. The results showed that higher hydrogen peroxide concentrations and higher humidity levels resulted in faster spore inactivation. Subvisible condensation enhanced inactivation, but visible condensation provided no further benefit. The deposition of water and hydrogen peroxide on surfaces, not gas phase concentration, was found to be the determining factor for microbial inactivation.
Gravimetric, mechanical and chemical characterization of different materials used in sewers systems: Polyvinyl chloride (PVC), polypropylene (PP) and high density polyethylene (HDPE), aged in sulfuric acid at 60°C
This document discusses primary and secondary standards used in pharmaceutical analysis. Primary standards are highly pure substances (99.95-100.05%) that are stable over temperature and used to standardize volumetric reagents. They must be easy to obtain and purify, soluble, and react stoichiometrically. Examples include potassium hydrogen phthalate and sodium carbonate. Secondary standards are solutions of known concentration determined by titrating against a primary standard. They have less purity and stability than primary standards and are used when primary standards are not practical, such as sodium hydroxide and potassium permanganate.
Optimizing the Reverse Osmosis Process Parameters by Maximizing Recovery by T...QUESTJOURNAL
ABSTRACT: In this study, the effects of Operating Pressure, Potential Hydrogen, Oxidation Reduction Potential and Anti Scaling Agent on multi responses like Permeate, COD, Total Solids, Conductivity and Hardness in the Reverse Osmosis Process were experimentally investigated on RO 8100 ST8 PT44 400Wl machine. The settings of RO parameters were determined by using Taguchi’s experimental design method. Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio, the analysis of variance (ANOVA) are employed to find the optimal levels and to analyze the effect of the RO parameters. Results show that potential of hydrogen, operating pressure, oxidation reduction potential and anti scaling agent are the four Parameters that influence the Permit more effectively and COD, Total Solids, Conductivity and Hardness respectively. Improvement in recovery of RO process is achieved with optimize setting. Finally, the ranges for best RO conditions are proposed for ZLD process.
E.G. Sreenivasula Reddy is seeking a position that utilizes his experience in analytical method development and validation for pesticides and chemicals. He holds an M.Sc. in Organic Chemistry and has over 10 years of experience in GLP certified laboratories developing and validating HPLC and GC methods. His responsibilities included residue analysis, environmental fate studies, and shelf-life testing. He is proficient in MS Office, knowledgeable in computer skills and instrumentation such as HPLC, GC, and FT-IR.
E.G. Sreenivasula Reddy is applying for positions with his resume. He has a M.Sc. in Organic Chemistry and experience working as a scientist and study director in GLP laboratories for various companies. His responsibilities included analytical method development, validations, residue analysis, and physicochemical property testing. He is proficient in MS Office and various analytical instruments. He has published 10 papers and presented at conferences. Reddy is looking for opportunities where he can contribute as a team member through hard work, dedication, and positive thinking.
Comprehensive Review of the Investigation of Anthropogenic and Naturally Occu...IJAEMSJORNAL
Authors attempt to depict a survey of anthropogenic 137Cs and naturally occurring radionuclides (226Ra, 228Th, 232Th, 214Bi, 208TI, 40K) in undistributed soil, water, ship scrapped materials such as metal, rubber and foam and tree bark of ship breaking area, cynoglossids i.e. tongue soles and tea leaves collected from different parts of Bangladesh for detecting health hazards, environmental protection and radiation safety of the public. The assessment of such radionuclides in these samples is utmost important due to nuclear test and accident, fallout and disposal of radioactive wastes. These radiotracers have been investigated by using laboratory-based Gamma Spectrometry for Food and Environmental Samples. The observation of activity concentrations for 137Cs, 226Ra, 228Th,232Th, 214Bi, 208TI and 40K have been presented in Bq.Kg-1. The others radiological parameters such as gamma ray dose rate (nGyh-1), Radium Equivalent Dose (Raeq) Bq.Kg-1, Representative Level Index (lr) Bq.Kg-1 and Transfer Factor (TF) %. The Radiation Hazard Index (Hx) Bq.Kg-1 also has been presented.
This document describes a dissertation that examines palladium-catalyzed Heck and Heck/Suzuki domino reactions, as well as applications of microwave heating technology in continuous flow organic synthesis. Specifically, the dissertation includes studies on: 1) developing a ligand-modulated approach to selectively attach aryl groups to a chelating vinyl ether, 2) evaluating a novel microwave applicator for heating solvents and reaction mixtures in continuous flow, 3) developing regioselective oxidative decarboxylative Heck reactions of electron-rich olefins, and 4) a theoretical mechanistic investigation of one such decarboxylative Heck reaction.
Study of Properties of Nanofluids and its EffectIRJET Journal
This document summarizes research on using nanofluids to enhance heat transfer in car radiators. It reviews studies that have shown nanofluids can increase the thermal conductivity and heat transfer coefficient of the coolant in radiators. Several key findings are discussed:
1) Adding nanoparticles like Al2O3 or CuO to the coolant increases the heat transfer coefficient and improves the cooling performance of the radiator.
2) Heat transfer is enhanced by up to 94% with 10% Al2O3 nanofluid and 89% with 6% CuO nanofluid.
3) For the same level of heat transfer, nanofluids reduce the pumping power required compared to the base fluid.
Synthesis and Characterization of Cationic Surfactants Based (1)Nesreen A. Fatthallah
1) The document describes the synthesis and characterization of four cationic surfactants based on N-hexamethylenetetramine and alkyl chlorides.
2) The surfactants were tested for their antimicrobial activity against four bacterial strains. The maximum activity was observed for N-hexamethylenetetramine-N-ethyl silane ammonium trichloride (Ah) which showed 73% inhibition of Staphylococcus aureus.
3) Surface tension measurements were performed to determine properties like critical micelle concentration and thermodynamic parameters of adsorption and micellization. Fourier transform infrared spectroscopy and mass spectrometry were used to characterize the synthesized surfactants.
Synthesis and Characterization of Hydroxyapatite/Graphene Oxide for Biomedica...IRJET Journal
This document summarizes a study that synthesized hydroxyapatite/graphene oxide composite for biomedical applications. Graphene oxide was first synthesized using a modified Hummers' method and hydroxyapatite/graphene oxide composite was prepared via co-precipitation. The composite was characterized using various techniques. XRD and FTIR confirmed the presence of hydroxyapatite and graphene oxide in the composite. SEM images showed the composite had a uniform morphology. The composite also demonstrated antibacterial properties against both gram-positive and gram-negative bacteria, indicating its potential for use in biomedical applications.
The synthesis of 1,4-dihydropyridines was performed in a continuous-flow microreactor. Elevated
temperatures accelerated the reaction rate significantly allowing the reaction to be finished in minutes
(6–11 min). Different 1,4-dihydropyridines were prepared in good to excellent isolated yields (45–88%
yield). The method was amenable to the preparation of daropidine, a calcium channel blocker which is
currently in clinical phase 3 trials.
The document summarizes the services provided by Golder Associates Research Laboratory (GARL), which includes conducting toxicity tests, analytical studies, and soil studies to evaluate the environmental impacts of contaminants. GARL uses standard testing techniques to measure the effects of substances discharged into the aquatic and terrestrial environment. They also work with other divisions at Golder to take an integrated scientific approach in areas like risk assessment, treatment processes, and monitoring programs. GARL is SANAS 17025 accredited and able to perform a wide range of analyses to assist clients across sectors like mining, oil and gas, manufacturing, and more.
Sodium Hypophosphite: An Efficient Catalyst for Synthesis of PyranopyrazolesIJSRED
This document summarizes research on using sodium hypophosphite as an efficient catalyst for the synthesis of pyranopyrazoles. A one-pot four component reaction is carried out with aldehydes, ethyl acetoacetate, hydrazine hydrate, and malononitrile in the presence of the sodium hypophosphite catalyst at room temperature. This protocol provides short reaction times, high yields, easy purification, and uses an economically available catalyst. Various pyranopyrazoles are synthesized with different aldehydes, and their melting points and spectral data are reported. Sodium hypophosphite is found to accelerate the reaction and provide a green, environmentally friendly synthesis method
Investigation of Metal and Chemical Hydrides for Hydrogen Storage in Novel Fu...chrisrobschu
DOE Funded Activities
Objectives:
•Use engineering analyses to screen H2 storage systems against DoD targets & requirements (FY15)
•Identify suitable hydrogen storage materials and suitable vehicle demonstration platforms
•Develop a preliminary design of an integrated UUV design with a solid hydrogen storage system
•Complete detailed design of the hydrogen storage system
•Complete integrated system design
ONR/NUWC Funded Activities
Objectives:
•
Design and build a small bench-scale, alane-based, hydrogen storage vessel
•
Perform preliminary testing on the bench-scale, storage system
•
Package and ship bench-scale vessel and alanematerial to the Navy NUWC
•
Provide technical support to Navy NUWC for their further testing and evaluation
Doe amr st134_motyka_2016_p
This document is a thesis submitted by Bh. Koti Reddy for the award of a Doctor of Philosophy (Engineering) degree from Jadavpur University, Kolkata. The thesis investigates the consolidation behavior of organic clays found in the Kolkata region of India. It includes laboratory testing of undisturbed soil samples collected from various locations to determine their index properties, microstructure, mineralogy, and classification. Both incremental loading (IL) consolidation tests and constant rate of strain (CRS) consolidation tests are conducted to study the consolidation behavior and parameters of the organic clays. The effects of organic content, strain rate, and loading duration are also evaluated. The thesis provides valuable data on the characterization and consolidation behavior
Modeling of variable speed compressor vapour compression refrigeration system...Husain Mehdi
Lots of researches have been done and going on based on the performance evaluation of various metallic/ nonmetallic nanoparticle suspended into the conventional fluid to enhance the heat transfer property of base fluid. Also some theoretical analysis of suspension of nanoparticle Al2O3 in conventional refrigerant. On the other hand the performance of vapour compression cycle based chiller facility using nano refrigerant yet to be analyzed with different type, concentration and diameter of nanoparticle. Such as TiO2, CuO nanoparticle suspension into conventional refrigerant with different concentration and diameter have been analyzed by several investigators and also effect of variation of concentration and nanoparticle diameter on the first and second law performance of vapour compression refrigeration system is presented. The effect of changing input parameter of VCRS using nano refrigerant also affecting significantly the evaporative heat transfer coefficient and very little condor heat transfer coefficient. The idea of Suspension nanoparticle into conventional refrigerant and theoretical analysis of VCRS using nano-refrigerant is proposed after going through extensive literature review presented in this paper.
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.
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.
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.
Deep Eutectic Solvent Delignification: Impact of Initial LigninMichal Jablonsky
This study investigated the effect of initial lignin content in hardwood kraft pulps on pulp delignification using deep eutectic solvents (DESs). Pulps with different initial Kappa numbers were treated with four DES systems and oxygen delignification for comparison. The results showed that DES delignification decreased the Kappa number by 37.8-43.3% depending on the DES, with alanine:lactic acid being most efficient. DESs caused less degradation than oxygen delignification as shown by smaller decreases in viscosity and degree of polymerization. The pulp with higher initial lignin had a greater fraction of easily removed lignin fragments.
This document reports on a study investigating the influence of sodium carboxymethylcellulose (NaCMC) on the aggregation behavior of aqueous solutions of 1-hexadecyl-3-methylimidazolium chloride (C16MeImCl), a cationic surface active ionic liquid (SAIL). Electrical conductivity and surface tension measurements were used to study C16MeImCl aggregation in the presence of NaCMC. Two characteristic concentrations were identified before free C16MeImCl micelles form: the critical aggregation concentration and the polymer saturation concentration. The effects of temperature, NaCMC concentration, and NaCMC charge density on C16MeImCl self-aggregation were analyzed. Thermodynamic parameters of C16MeImCl mic
Influence of Biofield Treatment on Physicochemical Properties of Hydroxyethyl...albertdivis
Hydroxyethyl cellulose (HEC) and hydroxypropyl cellulose (HPC) are widely explored as excipients to improve the solubility of poorly water soluble drugs and to improve self-life of dosage form. This work is an attempt to modulate the physicochemical properties of these cellulose derivatives using biofield treatment.
IRJET-Steel and Glass Fibre Reinforced Concrete: A ReviewIRJET Journal
1. Single crystals of disodium hydrogen phosphate (DSHP) were grown using a slow evaporation technique. Thermal analysis showed the crystals lose water below 131°C and undergo intermolecular condensation around 352°C.
2. Microhardness tests on the crystals found the hardness increases up to a load of 30g and remains constant at higher loads, indicating surface hardening.
3. Differential scanning calorimetry identified melting at 35.96°C and endothermic peaks corresponding to release of weakly absorbed and crystallization water, with all water released by 200°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.
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.
This document describes a study that evaluated a hybrid membrane bioreactor process for removing hydrogen sulfide (H2S) from biogas. The process used a polydimethylsiloxane membrane to first absorb H2S from biogas into an alkaline liquid, followed by biological oxidation of H2S in the liquid. The effects of absorption liquid pH, biogas flowrate, and dissolved oxygen concentration on H2S removal efficiency and selectivity were investigated. The results showed that pH 7 performed better than pH 8.5, and H2S removal exceeded 97% at flowrates below 148 g H2S/m3d and dissolved oxygen below 1 mg/L. This novel hybrid process provides an effective and low-cost
A short description of thermal technologies for the recovery of ammonia from N-rich wastewaters and expirementing with membrane distillation for getting better results.
This document summarizes a paper presented at the Second International Conference on New Research in Chemistry and Chemical Engineering. The paper presents an artificial neural network model developed to estimate the solubility of carbon dioxide in brine. The neural network takes temperature, pressure and salinity as inputs and outputs the estimated CO2 solubility. It is compared to the Duan and Sun (2003) model and Henry's correlation, showing improved performance over existing methods for a wide range of temperature, pressure and salinity conditions.
This document reviews the preparation, properties, and applications of nanofluids. It discusses:
1) Methods for preparing nanofluids and factors that influence their stability and thermal properties.
2) Experimental and theoretical models that have been used to analyze the thermal conductivity and other properties of nanofluids. Many studies found thermal conductivity increased significantly with only small amounts of nanoparticles.
3) Potential applications of nanofluids in various industries where enhanced heat transfer is important, such as electronics, automobiles, and power plants. However, issues around nanofluid stability and production costs need further research before wide commercial use.
1) Polysaccharide/protein nanomultilayer coatings were constructed by depositing alternating layers of κ-carrageenan and lysozyme on aminolyzed polyethylene terephthalate (PET) film.
2) The coatings were characterized and found to have low water vapor and oxygen permeability, indicating good barrier properties.
3) The nanomultilayer coating was then applied to fresh-cut and whole pears. Coated pears experienced less mass loss and maintained higher acidity and solid content than uncoated pears, demonstrating extended shelf-life.
This document summarizes a study that investigated the effects of water content and temperature on the reaction mechanism and crystal properties of paracetamol produced via reactive crystallization. The researchers first optimized the solubility of paracetamol by examining mixtures of acetic acid and water at different ratios and temperatures. They found the highest solubility occurred with a 7:3 ratio of acetic acid to water at 70°C. Based on this, they determined suitable amounts of reactants for the reaction. Experiments then examined how varying the water content (0, 10g, 20g) or temperature (50-80°C) impacted the reaction kinetics, products, and crystal properties. They found paracetamol form I crystals with 99
The effect of temperature onthe micellization of an anionic surfactant in mix...iosrjce
IOSR Journal of Applied Chemistry (IOSR-JAC) is a double blind peer reviewed International Journal that provides rapid publication (within a month) of articles in all areas of applied chemistry and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in Chemical Science. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
Thesis Publication_Journal of Fuel Processing Technology2016Ibrahim Ogunfayo
This research article studied how the mechanical properties of three types of wood pellets (white wood, torrefied, and steam-exploded) changed when exposed to different relative humidity (RH) and temperature conditions in a laboratory environment. The three pellet types were exposed to either high RH (90%) at ambient and elevated temperatures, or low RH (10%) at varying temperatures. Exposure to high RH and elevated temperatures caused a substantial decrease in the shear modulus of all three pellet types, with decreases ranging from 50% to 92% after 4 days. The steam-exploded pellets saw the lowest decrease in mechanical durability but the largest decrease in shear modulus. Storage at low RH did not cause observable degradation
Similar to Long-term Isothermal Stability of Deep Eutectic Solvents (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.
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.
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.
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.
Cellulose protectors for improving ozone bleaching - reviewMichal Jablonsky
The document reviews cellulose protectors that have been used to improve ozone bleaching processes. It systematically classifies protectors into 7 chemical groups and evaluates their effects on viscosity, kappa number, and brightness compared to bleaching without protectors. Alcohols and carboxylic acids are generally the most effective, positively impacting lignin removal while preventing carbohydrate degradation. Inorganic additives usually show no benefits. The protectors are thought to work by scavenging radicals, selective adsorption to cellulose, or forming protective compounds on the cellulose surface. Overall, no single protector was identified that strongly promotes lignin removal without also degrading cellulose.
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.
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.
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.
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.
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.
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.
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
KINETIC STUDY OF ARTEFACT PAPER DEGRADATION. ASSESS MENT OF DEACIDIFICATION ...Michal Jablonsky
The present study investigates the stabilization of a 60 year old paper artefact via deacidification. Paper sheets
originating from a naturally-aged artefact book were subjected to accelerated ageing performed at 98 °C during 0, 3, 5,
10 and 15 days. A set of samples were deacidified before being subjected to accelerated aging. Deacidification was
performed using magnesium ethoxide and titanium ethoxide (METE) dissolved in hexamethyldisiloxane (HMDO) and
the properties of the thus treated samples were measured and compared to control samples. This study aims at finding
kinetic dependences for the decrease in the degree of polymerization and folding endurance of the paper subjected to
accelerated ageing. The deacidification effects were evaluated by the folding endurance of the paper artefact through
the multifactorial evaluation system developed by Consortium KnihaSK and Library of Congress.
GREEN SOLVENTS BASED ON CHOLINE CHLORIDE FOR THE EXTRACTION OF SPRUCE BARK (P...Michal Jablonsky
Spruce bark is a rich source of extractives, such as condensed tannins, suberin, resin acids and terpenes. Deep eutectic solvents (DESs), a new type of green solvents, were used in this study for obtaining a spruce bark extract with valuable properties. Choline chloride-based eutectic solvents with carboxylic acids and glycerol were used as extractants. The extractions were performed for 1 h at 60 °C under continuous stirring. The antioxidant activities were evaluated using an antioxidant system with 2,2-diphenyl-1-picrylhydrazyl (DPPH). The content of the total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and expressed as gallic acid equivalent (GAE). The results indicated promising possibilities for the development and usage of eutectic solvents for bark pretreatment. All the tested extracts showed phenolic contents that ranged from 41 to 463 mg GAE/100 g extract. No correlation between the total phenolic content and antioxidant activity was observed. This study demonstrated that DESs are environmentally suitable solvents for extracting phenolic compounds from spruce bark.
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.
Describing and Interpreting an Immersive Learning Case with the Immersion Cub...Leonel Morgado
Current descriptions of immersive learning cases are often difficult or impossible to compare. This is due to a myriad of different options on what details to include, which aspects are relevant, and on the descriptive approaches employed. Also, these aspects often combine very specific details with more general guidelines or indicate intents and rationales without clarifying their implementation. In this paper we provide a method to describe immersive learning cases that is structured to enable comparisons, yet flexible enough to allow researchers and practitioners to decide which aspects to include. This method leverages a taxonomy that classifies educational aspects at three levels (uses, practices, and strategies) and then utilizes two frameworks, the Immersive Learning Brain and the Immersion Cube, to enable a structured description and interpretation of immersive learning cases. The method is then demonstrated on a published immersive learning case on training for wind turbine maintenance using virtual reality. Applying the method results in a structured artifact, the Immersive Learning Case Sheet, that tags the case with its proximal uses, practices, and strategies, and refines the free text case description to ensure that matching details are included. This contribution is thus a case description method in support of future comparative research of immersive learning cases. We then discuss how the resulting description and interpretation can be leveraged to change immersion learning cases, by enriching them (considering low-effort changes or additions) or innovating (exploring more challenging avenues of transformation). The method holds significant promise to support better-grounded research in immersive learning.
The debris of the ‘last major merger’ is dynamically youngSérgio Sacani
The Milky Way’s (MW) inner stellar halo contains an [Fe/H]-rich component with highly eccentric orbits, often referred to as the
‘last major merger.’ Hypotheses for the origin of this component include Gaia-Sausage/Enceladus (GSE), where the progenitor
collided with the MW proto-disc 8–11 Gyr ago, and the Virgo Radial Merger (VRM), where the progenitor collided with the
MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
The ability to recreate computational results with minimal effort and actionable metrics provides a solid foundation for scientific research and software development. When people can replicate an analysis at the touch of a button using open-source software, open data, and methods to assess and compare proposals, it significantly eases verification of results, engagement with a diverse range of contributors, and progress. However, we have yet to fully achieve this; there are still many sociotechnical frictions.
Inspired by David Donoho's vision, this talk aims to revisit the three crucial pillars of frictionless reproducibility (data sharing, code sharing, and competitive challenges) with the perspective of deep software variability.
Our observation is that multiple layers — hardware, operating systems, third-party libraries, software versions, input data, compile-time options, and parameters — are subject to variability that exacerbates frictions but is also essential for achieving robust, generalizable results and fostering innovation. I will first review the literature, providing evidence of how the complex variability interactions across these layers affect qualitative and quantitative software properties, thereby complicating the reproduction and replication of scientific studies in various fields.
I will then present some software engineering and AI techniques that can support the strategic exploration of variability spaces. These include the use of abstractions and models (e.g., feature models), sampling strategies (e.g., uniform, random), cost-effective measurements (e.g., incremental build of software configurations), and dimensionality reduction methods (e.g., transfer learning, feature selection, software debloating).
I will finally argue that deep variability is both the problem and solution of frictionless reproducibility, calling the software science community to develop new methods and tools to manage variability and foster reproducibility in software systems.
Exposé invité Journées Nationales du GDR GPL 2024
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
Immersive Learning That Works: Research Grounding and Paths ForwardLeonel Morgado
We will metaverse into the essence of immersive learning, into its three dimensions and conceptual models. This approach encompasses elements from teaching methodologies to social involvement, through organizational concerns and technologies. Challenging the perception of learning as knowledge transfer, we introduce a 'Uses, Practices & Strategies' model operationalized by the 'Immersive Learning Brain' and ‘Immersion Cube’ frameworks. This approach offers a comprehensive guide through the intricacies of immersive educational experiences and spotlighting research frontiers, along the immersion dimensions of system, narrative, and agency. Our discourse extends to stakeholders beyond the academic sphere, addressing the interests of technologists, instructional designers, and policymakers. We span various contexts, from formal education to organizational transformation to the new horizon of an AI-pervasive society. This keynote aims to unite the iLRN community in a collaborative journey towards a future where immersive learning research and practice coalesce, paving the way for innovative educational research and practice landscapes.
EWOCS-I: The catalog of X-ray sources in Westerlund 1 from the Extended Weste...Sérgio Sacani
Context. With a mass exceeding several 104 M⊙ and a rich and dense population of massive stars, supermassive young star clusters
represent the most massive star-forming environment that is dominated by the feedback from massive stars and gravitational interactions
among stars.
Aims. In this paper we present the Extended Westerlund 1 and 2 Open Clusters Survey (EWOCS) project, which aims to investigate
the influence of the starburst environment on the formation of stars and planets, and on the evolution of both low and high mass stars.
The primary targets of this project are Westerlund 1 and 2, the closest supermassive star clusters to the Sun.
Methods. The project is based primarily on recent observations conducted with the Chandra and JWST observatories. Specifically,
the Chandra survey of Westerlund 1 consists of 36 new ACIS-I observations, nearly co-pointed, for a total exposure time of 1 Msec.
Additionally, we included 8 archival Chandra/ACIS-S observations. This paper presents the resulting catalog of X-ray sources within
and around Westerlund 1. Sources were detected by combining various existing methods, and photon extraction and source validation
were carried out using the ACIS-Extract software.
Results. The EWOCS X-ray catalog comprises 5963 validated sources out of the 9420 initially provided to ACIS-Extract, reaching a
photon flux threshold of approximately 2 × 10−8 photons cm−2
s
−1
. The X-ray sources exhibit a highly concentrated spatial distribution,
with 1075 sources located within the central 1 arcmin. We have successfully detected X-ray emissions from 126 out of the 166 known
massive stars of the cluster, and we have collected over 71 000 photons from the magnetar CXO J164710.20-455217.
hematic appreciation test is a psychological assessment tool used to measure an individual's appreciation and understanding of specific themes or topics. This test helps to evaluate an individual's ability to connect different ideas and concepts within a given theme, as well as their overall comprehension and interpretation skills. The results of the test can provide valuable insights into an individual's cognitive abilities, creativity, and critical thinking skills
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...
Long-term Isothermal Stability of Deep Eutectic Solvents
1. See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/327141953
Long-term Isothermal Stability of Deep Eutectic Solvents
Article in Bioresources · August 2018
DOI: 10.15376/biores.13.4.7545-7559
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Slovak University of Technology in Bratislava
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Slovak University of Technology in Bratislava
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Long-term Isothermal Stability of Deep Eutectic
Solvents
Michal Jablonský,*a
Andrea Škulcová,a
Aleš Ház,a
Jozef Šima,b
and Veronika Majová a
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.
Keywords: Deep eutectic solvents; Long-term stability; Clean production; Green chemistry
Contact information: a: Slovak University of Technology in Bratislava, 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: Slovak University of Technology in Bratislava,
Faculty of Chemical and Food Technology, Institute of Inorganic Chemistry, Technology and Materials,
Department of Inorganic Chemistry, Radlinského 9, Bratislava, 812 37, Slovak Republic;
* Corresponding author: michal.jablonsky@stuba.sk
INTRODUCTION
Biomass can undergo traditional treatment methods or be transformed into other
raw materials, biofuels, and biochemicals. The upgrading of existing technologies and the
development of new biorefinery procedures are support for the transformation of biomass.
Valorisation is a key factor for an economic lignocellulosic biorefinery (Jablonský et al.
2015; Šurina et al. 2015). A simple, clean fractionation of the biomass’ main components
represents an important step in the renewable, “clean” carbon economy. One of the
promising technologies is the use of ionic liquids. Ionic liquids can be applied in obtaining
new products from biomass, where they are used as solvents when recycling polymeric
materials and electrochemical plating; as a portable media in solar systems; as a transport
medium for reactive gases; and, most recently, in biotechnology, e.g. for enzymatic
hydrolysis (Abbott et al. 2003, 2004). A relatively new generation of ionic liquids, known
as deep eutectic solvents (DESs), is another important group of advanced solvents used to
dissolve lignocellulosic biomass and enable its processing (Carriazo et al. 2012; Francisco
et al. 2012; Zhang et al. 2012). Generally, DESs are obtained by mixing two substances, a
hydrogen donor and a hydrogen acceptor that can be mutually connected through hydrogen
bonding (Zhang et al. 2012).
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Developments in this area have been sharply expanding, as indicated by recent
publications and patented applications that use DESs for dissolving the individual
components of biomass (Jablonsky et al. 2018). Some papers focus on the extraction of
valuable compounds from biomass using a deep eutectic solvent. DESs were used to extract
flavonoids from the plants Camaecyparis obtusa, Carthamus tinctorius, and Flos sophorae
as well as from model oil (Bi et al. 2013; Dai et al. 2013a,b; Gu et al. 2014; Nam et al.
2015; Tang et al. 2015). Especially promising is current research into obtaining flavonoids
through a NADESs. Such work (De Dios 2013; Kroon et al. 2013; Jablonský et al. 2015;
Kumar et al. 2016a) has focused on the use of DESs in the fractionation process or the
separation process of the biomass components. As new types of ionic liquids, DESs can be
used in fractionation processes or extraction of different types of substances from various
agricultural and silvicultural vegetation. Extraction and fractionation methods as well as a
solvent should be chosen considering the sample matrix properties, the chemical properties
of the analytes, the matrix-analyte interactions, efficiency and speed, environmental
friendliness, and cost (Co et al. 2011; Zheljazkov et al. 2012, 2013; Nađalin et al. 2014).
Thermodynamic properties of DESs, such as glass transition temperature, melting
temperature, thermal decomposition temperature, heat capacity, enthalpy, and entropy of
phase transitions are important data for the understanding of these liquids and their
application in different sectors. Adiabatic calorimetry and techniques of thermal analysis
can be used to determine thermodynamic properties of DESs (Tan et al. 2011). Studies
dealing with DESs have been based on the assumption that DESs will exhibit negligible
vapor pressure. Any evaluation of DESs thermal properties is, due to their volatile nature,
critical for their intended application (Kamavaram and Reddy 2008). Vapor pressure is
influenced mainly by the hydrogen-bond acceptor (HBA) and donor (HBD) combination
that is inherent in forming a DES. Thermogravimetric analysis (TGA) is one of the
commonly used methods to determine the thermal stability of materials and substances
(Cao and Mu 2014; Chemat et al. 2016; Deferm et al. 2018). Numerous DESs have been
reported to be stable in their liquid form up to temperatures of 150 °C or higher (Chen et
al. 2018). The obtained results were duly evaluated, taking various experimental conditions
into account. In the case of the used TGA technique they referred mainly to the carrier gas,
the sample purity, the heating rate, and the sample mass (Chen et al. 2018). Especially, it
was pointed out that dynamic TGA studies with a fast heating rate (≥10 °C min-1
) lead to
gross overestimations of the thermal stability (Cao and Mu 2014; Deferm et al. 2018;
Maton et al. 2013; Villanueva et al. 2013). The temperature limit of ionic liquids stability
is not precisely defined by the onset decomposition temperature (Dai et al. 2013a;
Kamavaram and Reddy 2008). Studies on long-term stability are limited, and most
investigations focus on conventional ionic liquids (Cao and Mu 2014; Clough et al. 2013;
Peng et al. 2010). However, a few works on the thermal stability of DESs have been
published too (Deferm et al. 2018; Ghaedi et al. 2018; Morrison et al. 2009; Skulcova et
al. 2017; Chen et al. 2018). It was shown that dynamic TGA is no longer reliable for
estimating the thermal stability even at low heating rates, and the method often leads to
overestimations of the long-term thermal stabilities (Deferm et al. 2018; Maton et al.
2013). Static TGA provides more reliable thermal stability data and should be
preferentially used. Investigation of the long-term stability of DESs is very important for
industrial applications, in which DESs must endure certain high temperature for a period
of time (Chen et al. 2018).
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The main objective of this study was to characterize long-term thermal stability of
DESs. The term “thermal stability” means that the composition of DES components and
their products does not change in a certain operational temperature range. Moreover, no
turbidity is formed within the time of the DES application. These requirements are met
even in the case of evaporation of a small portion of water. In our work, isothermal TGA
at different temperature intervals were used to determine the long-term stability of mixtures
based on choline chloride in combination with oxalic acid dehydrate (molar ratio 1:1);
glycerol (1:2); glycolic acid (1:3); malic acid (1:1); and citric acid monohydrate (1:1).
Long-term stability of these DESs was evaluated because choline chloride-based eutectic
solvent with carboxylic acids and glycerol were used as extractants for the extracting of
polyphenolic compounds from spruce bark. The results obtained were recently published
by Skulcova et al. (2018). Extractions were performed for 1 h at 60 °C under continuous
stirring. The work focused on investigation of thermal stability describing behaviour of the
prepared DESs exposed to various temperatures at isothermal conditions. The stability of
these mixtures were characterized from the viewpoint of the loss of mass (supposed bound
and/or unbound water loss), the loss of DESs components, and thermal decomposition of
DESs components. In addition, long-term thermal stability was followed by determination
of water content not taken into account at the stability evaluation. This is the stability
informing on mass loss due to isothermal impact of heat and involving evaporation of DES
components and their decomposition.
EXPERIMENTAL
Materials
Glycerol (99%) and citric acid monohydrate (≥ 98%) were obtained from
Centralchem, s.r.o. (Bratislava, Slovakia). Choline chloride (≥ 98%), malic acid (≥ 98%),
glycolic acid (99%), and oxalic acid dihydrate (≥ 99%) were purchased from Sigma-
Aldrich (Bratislava, Slovakia).
The deep eutectic solvents were prepared according to the procedure previously
reported (Jablonský et al. 2015). The solvents were prepared with choline chloride and
oxalic acid dihydrate; glycerol; glycolic; malic acid; and citric acid monohydrate. Choline
chloride was dried in a vacuum oven at 40 °C prior to its use to eliminate moisture
contamination, the chemicals were used as received.
Determination of water content
The water contents were determined with a TITRINO 702 SM from Metrohm Ltd.
(Herisau, Switzerland), and coulometric Karl-Fischer titration.
Density
Densities were determined with a pycnometer. The samples density was measured
at different temperatures (23 °C to 75 °C). All measurements were performed three times
with individual samples.
Viscosity
The viscoelastic properties were characterized on a Brookfield DV- II + Pro
rotating viscometer from Ecotest, s.r.o. (Bratislava, Slovakia). The samples viscosity was
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measured at different temperatures (28 °C to 60 °C) at different revolutions (5, 10, 20, 50,
and 100 RPM) using a spindle 18 with an adapter. All measurements were performed three
times with individual samples.
pH measurement
The pH was measured in aqueous solutions of DES at a concentration of 0.5 mol/L.
The pH was determined using a digital pH meter from Hanna Instruments (Bratislava,
Slovakia). The samples were heated to the desired temperature at 23 °C to 60 °C.
Conductivity measurement
Conductivity was measured using a DiST4 conductivity meter from Hanna
Instruments (Bratislava, Slovakia) at ambient temperature. All measurements were
performed three times with individual samples.
Table 1. Compositions and Abbreviations of Prepared DESs
Abbreviation DES Molar Ratio
Water Content**
(%)
DES1 ChCl*:Oxalic acid dihydrate 1:1 14.27
DES2 ChCl:Glycerol 1:2 0.31
DES3 ChCl:Glycolic acid 1:3 5.25
DES4 ChCl:Malic acid 1:1 2.86
DES5 ChCl:Citric acid monohydrate 1:1 6.82
*Choline chloride
**Karl Fisher method
Methods
Long-term isothermal stability
A thermogravimetric analyser/Differential scanning calorimeter 1 (TGA/DSC)
instrument from Mettler Toledo (Bratislava, Slovakia) was used to perform the
thermogravimetric analysis of DESs. The analysis was performed in a reduction
atmosphere (nitrogen, 50 mL/min). The long-term stability was conducted at isothermal
mode. Isothermal thermogravimetry was performed at a constant temperature for 10 h.
Measurements were taken in the temperature range from 60 °C to 120 °C at 20 °C intervals.
RESULTS AND DISCUSSION
The long-term thermal behaviour of DESs was investigated using isothermal
studies for 10 h with a nitrogen purge at 50 mL/min. The results obtained at different
temperatures are shown in Figs. 1 through 5. Nonlinear weight vs. time dependences were
observed in the range 60 °C to 120 °C at intervals of 10 °C. Table 2 illustrates the
comparison of weight change of the deep eutectic solvents as a function of temperature
after 10 h of isothermal thermogravimetry. Weight differences between 3.1% and 5.9%
were recorded at 60 °C, a difference mainly due to air humidity. At 120 °C these differences
were between 11.7% and 34.6%.
The greatest weight loss was confirmed when the eutectic solvent was prepared
from choline chloride and citric acid monohydrate. Citric acid monohydrate has bound
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water that is released between 70 °C and 100 °C. Faster heating increases the temperature
at which the water evaporates, and heating at lower temperatures results in a slower
evaporation of the bound water. A weight loss of 34.58% was observed at 120 °C, which
was a remarkable difference from the 7.3% experienced at 100 °C. Based on the evaluation
of the thermal stability of DESs, it was concluded that these solvents have different
stabilities.
The stability of the solvents proceeded in the following order: DES choline chloride
with, respectively, malic acid (11.7%), glycerol (12.9%), glycolic acid (15.6%), oxalic acid
dehydrate (18.3%), and citric acid monohydrate (34.6%), at 120 °C and 10 h. Provided that
the temperature while applying isothermal methods was 80 °C, the most stable was DES
choline chloride with malic acid (weight loss of 4.4%) > glycerol (5.0%) > citric acid
monohydrate (5.2%) > oxalic acid dihydrate (7.3%) > glycolic acid (11.7%). Conversely,
the stability at 60 °C ascended in the following order: DES choline chloride with,
respectively, citric acid monohydrate (3.1%), malic acid (4.2%), glycerol (4.7%), oxalic
acid dehydrate (4.9%), and glycolic acid (5.9%).
The above results describe the actual thermal stability of the prepared samples that
also contained water (Table 1). The phenomena related to water content changes were
described and explained by van Osch et al. (2015), Sheldon (2016), and Zhekenov et al.
(2017). NMR investigation of aqueous systems with various concentrations of DESs
showed that the DESs chemical properties are invariable in a relatively large concentration
range span. DESs are frequently applied mixed with water. Their components can react
with water, producing new compounds which themselves do not form the DESs. However,
usually the components are weak acids and bases. The equilibrium constants of their
protolytic reaction with water are therefore low, which means that even in the presence of
water the components in practice should not change their composition and structure. On
the other hand, it is known that the presence of water in a DES system and its effect on the
efficiency of extraction strongly depends on the water content. It is well known, that the
presence of water can have a strong influence mainly on dynamic TGA results. Comparison
of the thermal stability of DESs at 120 °C without water content was as follows: DES
choline chloride with, respectively, oxalic acid dihydrate (4.0%), malic acid (8.8%),
glycolic acid (10.4%), glycerol (12.6%), and citric acid monohydrate (27.8%) at 120 °C
and 10 h. The long-term stability of the examined DES choline chloride with, respectively,
oxalic acid dehydrate, glycerol, glycolic, malic acid, and citric acid monohydrate indicated
that these types of fluids could have practical potential use in many industrial applications
and as a solvent in fractionation and extraction processes.
Table 2. Weight Loss of the Deep Eutectic Solvents as a Function of
Temperature After 10 h
DES 60 °C 80 °C 100 °C 120 °C
Weight Loss After 10 h (%)
ChCl*:Oxalic acid × 2H2O 4.9 7.3 10.3 18.3
ChCl:Glycerol 4.7 5.0 6.7 12.9
ChCl:Glycolic acid 5.9 11.7 12.2 15.6
ChCl:Malic acid 4.2 4.4 6.6 11.7
ChCl:Citric acid × H2O 3.1 5.2 7.3 34.6
*Choline chloride
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0 5000 10000 15000 20000 25000 30000 35000
80
82
84
86
88
90
92
94
96
98
100
Weight(%)
Time (s)
60 °C
80 °C
100 °C
120 °C
Fig. 1. Isothermal thermogravimetry of DES1, choline chloride and oxalic acid × 2H2O, molar ratio
1:1, at different temperatures under nitrogen purge (50 mL/min)
0 5000 10000 15000 20000 25000 30000 35000
80
82
84
86
88
90
92
94
96
98
100
Weight(%)
Time (s)
60 °C
80 °C
100 °C
120 °C
Fig. 2. Isothermal thermogravimetry of DES2, choline chloride and glycerol, molar ratio 1:2, at
different temperatures under nitrogen purge (50 mL/min)
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0 5000 10000 15000 20000 25000 30000 35000
80
82
84
86
88
90
92
94
96
98
100
Weight(%)
Time (s)
60 °C
80 °C
100 °C
120 °C
Fig. 3. Isothermal thermogravimetry of DES3, choline chloride and glycolic acid, molar ratio 1:3,
at different temperatures under nitrogen purge (50 mL/min)
0 5000 10000 15000 20000 25000 30000 35000
80
82
84
86
88
90
92
94
96
98
100
Weight(%)
Time (s)
60 °C
80 °C
100 °C
120 °C
Fig. 4. Isothermal thermogravimetry of DES4, choline chloride and malic acid, molar ratio 1:1, at
different temperatures under nitrogen purge (50 mL/min)
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0 5000 10000 15000 20000 25000 30000 35000
60
65
70
75
80
85
90
95
100
Weight(%)
Time (s)
60 °C
80 °C
100 °C
120 °C
Fig. 5. Isothermal thermogravimetry of DES5, choline chloride and citric acid × H2O, molar ratio
1:1, at different temperatures under nitrogen purge (50 mL/min)
20 30 40 50 60 70 80
1160
1180
1200
1220
1240
1260
1280
1300
1320
1340
1360
Density(kg/m
3
)
Temperature (°C)
DES1
DES4
DES3
DES2
DES5
Fig. 6. Densities of DESs as a function of temperature
Density is an important property for chemical materials and their processing. In
general, the densities of DESs exhibit higher values than that of water. For many
applications it is important to know how temperature affects density (Hayyan et al. 2012).
The density is dependent upon the packing and molecular organisation of the DES (Abbott
et al. 2007) and on the water content, as it decreases with an increased percentage of water
(Yadav and Pandey 2014; Yadav et al. 2014).
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The increase in temperature results in more molecular activity and mobility
(Kareem et al. 2010). The studied DESs density measurements were conducted as a
function of temperature in the range of 23 °C to 75 °C. The effect of temperature on the
densities of different DES is depicted in Fig. 6. The measured densities of the DESs were
less than 1352 kg/m3
. The reduction in density was linear for all studied DESs. The highest
density was that of DES5 with the molar ratio 1:3, which reached a maximum of 1352
kg/m3
at 23 °C and a minimum of 1315.5 kg/m3
at 75 °C. In contrast, DES2 had the lowest
density (1170.6 kg/m3
at the highest temperature of 75 °C). One way to achieve a lower
extraction cost is to run the process at lower temperatures. The disadvantage of lower
temperatures is the resulting higher density and viscosity of the deep eutectic solvent,
which influences the penetration into the matrix, while extending the extraction time and
influencing the process´s efficiency. The results of this work showed that an increased
temperature resulted in a reduction in the density and facilitated the penetration of the DESs
into the matrix. These results suggested that, in terms of thermal stability, it was more
beneficial to use lower extraction temperatures, but that viscosity and density of the deep
eutectic solvent at low temperature prevented the extraction process. Therefore, it could be
appropriate to optimize the process parameters to work at higher temperatures while also
preventing remarkable thermal degradation of the DES at these temperatures. According
to the results of this paper, it is advisable to apply temperatures lower than 80 °C during
the extraction and fractionation processes.
Conductivity as a summation parameter measures the concentration level of ions in
the solution. The measured values varied from 0.00 mS/cm to 4.95 mS/cm. It has been
observed that dicarboxylic acid-containing DESs exhibited higher conductivity compared
with other DESs investigated (Abbott et al. 2004). The work of Smith et al. (2014) has
shown the conductivity of DES choline chloride:ethylene glycol (1:2) is 7.61 mS/cm,
which is considerably more than chlorine:oxalic acid (1:1). The conductivity of DES
choline chloride:glycerol is close to the conductivity interval for natural drinking and
surface water, which is 0.1 mS/cm to 1 mS/cm. The work of Zhang et al. (2012) measured
the conductivity of selected DESs, with the choline chloride:glycerol conductivity at 1.05
mS/cm, which corresponds to the results of the present study.
The conductivity of DES choline chloride:citric acid was not measurable under the
given conditions. Its high density did not allow the immersion of the electrode.
The DES choline chloride:malic acid has proven to be non-conductive. The work
of Kumar et al. (2016b) measured the conductivity of DES choline chloride:malic acid as
0.197 mS/cm (at ambient temperature). Kumar et al. (2016b) also observed the effect of
water on the conductivity of DES and found that an increase in the content of DES water
resulted in increased conductivity to a maximum point after which it decreased. This
property may have been the reason for the different conductivities of the same DES.
Table 3. Conductivities of DESs at Ambient Temperature
Abbreviation DES Conductivity mS/cm
DES1 ChCl:Oxalic acid dihydrate 4.95
DES2 ChCl:Glycerol 1.05
DES3 ChCl:Glycolic acid 1.24
DES4 ChCl:Malic acid 0.00
DES5 ChCl:Citric acid monohydrate ND*
*Not detected
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0.0029 0.0030 0.0031 0.0032 0.0033 0.0034
3.5
4.0
4.5
5.0
5.5
6.0
0.0029 0.0030 0.0031 0.0032 0.0033 0.0034
3.5
4.0
4.5
5.0
5.5
6.0
0.0029 0.0030 0.0031 0.0032 0.0033 0.0034
3.5
4.0
4.5
5.0
5.5
6.0
DES3
ln(viscosity)(mPa.s)
DES1
Temperature
-1
(K
-1
)
DES2
Fig. 7. Temperature dependence of dynamic viscosity measured for DESs
The temperature dependence of dynamic viscosity measured for DESs is shown in
Fig. 7. Due to device limitations and high density, it was not possible to measure the
dynamic viscosity of choline chloride:malic acid and choline chloride:citric acid. As with
many liquids, the viscosity was also a noticeable physical quantity for DESs. Deep eutectic
solvents have a relatively high viscosity compared with water, due to the hydrogen bonds
between components. The presence of Van der Waals interactions, electrostatic
interactions, and the size of ions forming the DES can also contribute to high viscosity
(Zhang et al. 2012). Because DESs are considered a new group of solvents, it is desirable
to find DESs with low viscosity to ensure the functionality of the solvent. The viscosity of
the resulting solvent is strongly dependent upon the temperature and water content of the
starting materials (Zhang et al. 2012). At room temperature, the highest dynamic viscosity
value was DES2 choline chloride:glycerol, and the lowest was DES1 choline
chloride:oxalic acid. At 60 °C, the highest value was also DES2 and the lowest was DES1,
and so the trend was maintained. Zhang et al. (2012) examined the viscosity of DESs from
various works. The DES choline chloride:glycerol (1:2) had a viscosity of 376 cP (20 °C)
and 259 cP (25 °C). The DES was measured at 28 °C and 291.2 mPa.s, corresponding to
291.2 cP.
The viscosities of most DESs vary considerably with temperature changes. The
dependence of viscosity on temperature has an Arrhenian character. The dependence of
natural logarithm from T-1
was linear and its slope and intercept were evaluated (Table 4).
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Table 4. Values of Parameters Slope and Intercept for Equation ln(η) = a + b(T-1)
for Viscosity (mPa.s) in the Temperature Range 301.15 to 343.15 K
Abbreviation Slope (a) Intercept (b)×10-3
DES1 -10.961 4.934
DES2 -11.090 5.041
DES3 -8.536 4.027
The chemical nature of hydrogen bond donor (HBD) had a strong effect on the
acidity or alkalinity of the resulting DES. The prepared DES in this study had a distinct
acidic character because HBD are organic acids and tri-alcoholic glycerol. The pH of the
DES with glycerol was higher than the pH of the DES containing an organic acid. With
increasing temperature, the pH decreases, while the DES choline chloride:oxalic acid was
0.05 at 60 °C. The pH change with increasing temperature for DES choline
chloride:glycolic acid and glycerol had a slight downward tendency. The pH of both DESs
choline chloride:malic acid and choline chloride:citric acid decreased remarkably with
rising temperatures. Similarly, the pH also decreased for choline chloride:oxalic acid.
Table 5. Values of Parameters Slope and Intercept for Equation pH = a + b(T) for
pH in the Temperature Range 24 to 60 °C
Abbreviation Slope (a) Intercept (b)×103
DES1 2.037 -32.60
DES2 4.721 -10.27
DES3 1.409 -6.79
DES4 2.082 -19.28
DES5 2.298 -23.39
CONCLUSIONS
1. Long-term isothermal thermogravimetry studies of the deep eutectic solvents showed
non-linear weight loss as a function of time at each recorded temperature. Preferably,
the fractionation or dissolution of biomass should be conducted below 80 °C.
2. The density of the investigated DESs decreased with increased temperature.
3. The pH of the DES with glycerol was noticeably higher than the pH of the DES
containing an organic acid; these pHs were below 2.3. The DES containing glycerol
had a pH of up to approximately 4.7. As the temperature increased, the pH decreased.
ACKNOWLEDGMENTS
This work was supported by the Slovak Research and Development Agency under
the following grant Nos.: APVV-15-0052, APVV-0393-14, and APVV-16-0088. The
authors would like to thank the STU Grant scheme for the Support of Young Researchers
under contract Nos. 1663, 1696 and 1697 for financial assistance.
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Article submitted: May 31, 2018; Peer review completed: July 18, 2018; Revised version
received: August 1, 2018; Accepted: August 2, 2018; Published: August 21, 2018.
DOI: 10.15376/biores.13.4.7545-7559
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