This document discusses using deep eutectic solvents (DESs) and natural surfactants for removing lead from contaminated soil. DESs were prepared using choline chloride mixed with various hydrogen bond donors like fructose, sucrose, glycerol, and ethylene glycol. Addition of a natural surfactant called saponin, extracted from soapnut fruit, improved the lead removal efficiency of the DESs. Batch tests showed the fructose-based DES combined with 1% saponin solution removed up to 72% of lead from the contaminated soil. The DESs act as mild acids and the saponin further enhances removal by supplying hydrogen ions. This study suggests natural compound-based DESs have
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.
Natural Deep Eutectic Solvents as Agents for Improving Solubility, Stability ...Maciej Przybyłek
Purpose
Study on curcumin dissolved in natural deep eutectic solvents (NADES) was aimed at exploiting their beneficial properties as drug carriers.
Methods
The concentration of dissolved curcumin in NADES was measured. Simulated gastrointestinal fluids were used to determine the concentration of curcumin and quantum chemistry computations were performed for clarifying the origin of curcumin solubility enhancement in NADES.
Results
NADES comprising choline chloride and glycerol had the highest potential for curcumin dissolution. This system was also successfully applied as an extraction medium for obtaining curcuminoids from natural sources, as well as an effective stabilizer preventing curcumin degradation from sunlight. The solubility of curcumin in simulated gastrointestinal fluids revealed that the significant increase of bioavailability takes place in the small intestinal fluid.
Conclusions
Suspension of curcumin in NADES offers beneficial properties of this new liquid drug formulation starting from excreting from natural sources, through safe storage and ending on the final administration route. Therefore, there is a possibility of using a one-step process with this medium. The performed quantum chemistry computations clearly indicated the origin of the enhanced solubility of curcumin in NADES in the presence of intestinal fluids. Direct intermolecular contacts leading to hetero-molecular pairs with choline chloride and glycerol are responsible for elevating the bulk concentration of curcumin. Choline chloride plays a dominant role in the system and the complexes formed with curcumin are the most stable among all possible homo- and hetero-molecular pairs that can be found in NADES-curcumin systems.
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.
Pretreatment of wheat straw using deep eutectic solvents and ultraoundEuropeanPaper
By Andrea Skulcova, Slovak University of Technology. This was presented during the Two Team Project - Winners' first successes session, organised as part of European Paper Week 2015. More at http://www.cepi.org/epw
Deep Eutetic Solvents for Biomass Activation by Sauli Vuoti, Jaakko Hiltunen et al., VTT
ACel Programme Seminar June 5, 2015
http://fibic.fi/events/acel-program-seminar-jun-5-cellulose-reactivity-and-recycling-of-ionic-liquids
The current investigation presents the role of gooseberry (Phyllanthus acidus) seeds as an effective biosorbent for remediating chromium (VI)), a toxic heavy metal pollutant commonly found in effluents from tanneries and relevant industries. Biosorption was affected by pH, temperature and initial metal concentration. Furthermore, there is a need to understand the holistic effect of all variables to ascertain the best possible conditions for adsorption, therefore, these factors were considered and a total of 17 trials were run according to the Box Behnken design. Quadratic model had maximum R2 value (0.9984) and larger F value (1109.92). From the Analysis Of Variance table and R2 value, quadratic model was predicted to be the significant model with the best fit to the generated experimental data. The optimal parameters obtained from the contour plot for the maximum removal of chromium(VI) were initial metal concentration of 60 mg/L, pH value of 2, and temperature of 27°C. Under these conditions, maximum removal of 92% was obtained. Thus this biosorbent substantially eliminates chromium(VI) under optimized conditions, enabling its use in larger scale.
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.
Natural Deep Eutectic Solvents as Agents for Improving Solubility, Stability ...Maciej Przybyłek
Purpose
Study on curcumin dissolved in natural deep eutectic solvents (NADES) was aimed at exploiting their beneficial properties as drug carriers.
Methods
The concentration of dissolved curcumin in NADES was measured. Simulated gastrointestinal fluids were used to determine the concentration of curcumin and quantum chemistry computations were performed for clarifying the origin of curcumin solubility enhancement in NADES.
Results
NADES comprising choline chloride and glycerol had the highest potential for curcumin dissolution. This system was also successfully applied as an extraction medium for obtaining curcuminoids from natural sources, as well as an effective stabilizer preventing curcumin degradation from sunlight. The solubility of curcumin in simulated gastrointestinal fluids revealed that the significant increase of bioavailability takes place in the small intestinal fluid.
Conclusions
Suspension of curcumin in NADES offers beneficial properties of this new liquid drug formulation starting from excreting from natural sources, through safe storage and ending on the final administration route. Therefore, there is a possibility of using a one-step process with this medium. The performed quantum chemistry computations clearly indicated the origin of the enhanced solubility of curcumin in NADES in the presence of intestinal fluids. Direct intermolecular contacts leading to hetero-molecular pairs with choline chloride and glycerol are responsible for elevating the bulk concentration of curcumin. Choline chloride plays a dominant role in the system and the complexes formed with curcumin are the most stable among all possible homo- and hetero-molecular pairs that can be found in NADES-curcumin systems.
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.
Pretreatment of wheat straw using deep eutectic solvents and ultraoundEuropeanPaper
By Andrea Skulcova, Slovak University of Technology. This was presented during the Two Team Project - Winners' first successes session, organised as part of European Paper Week 2015. More at http://www.cepi.org/epw
Deep Eutetic Solvents for Biomass Activation by Sauli Vuoti, Jaakko Hiltunen et al., VTT
ACel Programme Seminar June 5, 2015
http://fibic.fi/events/acel-program-seminar-jun-5-cellulose-reactivity-and-recycling-of-ionic-liquids
The current investigation presents the role of gooseberry (Phyllanthus acidus) seeds as an effective biosorbent for remediating chromium (VI)), a toxic heavy metal pollutant commonly found in effluents from tanneries and relevant industries. Biosorption was affected by pH, temperature and initial metal concentration. Furthermore, there is a need to understand the holistic effect of all variables to ascertain the best possible conditions for adsorption, therefore, these factors were considered and a total of 17 trials were run according to the Box Behnken design. Quadratic model had maximum R2 value (0.9984) and larger F value (1109.92). From the Analysis Of Variance table and R2 value, quadratic model was predicted to be the significant model with the best fit to the generated experimental data. The optimal parameters obtained from the contour plot for the maximum removal of chromium(VI) were initial metal concentration of 60 mg/L, pH value of 2, and temperature of 27°C. Under these conditions, maximum removal of 92% was obtained. Thus this biosorbent substantially eliminates chromium(VI) under optimized conditions, enabling its use in larger scale.
Fertilizer plant waste carbon slurry has been investigated after some processing as an adsorbent for the removal of dyes and phenols using columns. The results show that the carbonaceous adsorbent prepared from carbon slurry being porous and having appreciable surface area (380 m2/g) can remove dyes both cationic (meldola blue, methylene blue, chrysoidine G, crystal violet) as well as anionic (ethyl orange, metanil yellow, acid blue 113), and phenols (phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol) fruitfully from water. The column type continuous flow operations were used to obtain the breakthrough curves. The breakthrough capacity, exhaustion capacity and degree of column utilization were evaluated from the plots. The results shows that the degree of column utilization for dyes lies in the range 60 to 76% while for phenols was in the range 53-58%. The exhaustion capacities were quite high as compared to the breakthrough capacities and were found to be 217, 211, 104, 126, 233, 248, 267 mg/g for meldola blue, crystal violet, chrysoidine G, methylene blue, ethyl orange, metanil yellow, acid blue 113, respectively and 25.6, 72.2, 82.2 and 197.3 mg/g for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol, respectively
ABSTRACT- Tagetes erecta L. was raised in pots containing soil treated with various concentrations of Pb(NO3)2 (500, 1000, 1500, 2000 and 2500mg/kg). At maturity plants were separated into root, stem, leaves and inflorescence and lead accumulated in each part was quantified. The effects of lead accumulation on growth was analyzed by the measurement of various growth parameters like root and shoot length, fresh and dry weight of root and shoot and total leaf area per plant. Moreover effect of lead accumulation on biochemical parameters was checked by quantitative estimation of various biochemical parameters like chlorophyll, total protein, free amino acids, total sugar, reducing sugar and starch. Results showed that there is no remarkable negative effect of accumulation of lead on the morphological growth of the plant. Biochemical analysis showed that amount of total protein continuously decreased whereas that of free amino acids continuously increased with increasing concentrations of lead. Amount of chlorophyll, total sugar, reducing sugar and starch contents continuously increased till mid-level i.e., Pb 1500 mg/kg and then continuously decreased at higher concentrations. Results of quantitative estimation of Pb in root, stem, leaves and inflorescence showed that roots accumulated highest amount of Pb followed by stem and leaves, whereas inflorescence contained least amount of Pb.
Key-words- Lead (Pb), Heavy metal, Tagetes erecta L., Accumulation, Phytoremediation
Batch adsorption experiments were carried out for
the adsorption of cationic dye from aqueous solution onto
composite activated carbon. The composite activated carbon was
prepared from brewer’s spent grain and sea bean shell at a ratio
of 1:1. The equilibrium studies were done at different
concentrations and temperatures. The equilibrium data were
fitted to Langmuir, Freundlich, Dubinin-Radushkevich, and
Temkin isotherm models. The results showed that both Lagmuir
and Freundlich isotherm model fitted the data reasonably well
but Freundlich isotherm fitted better in the temperature range
studied. This confirmed that the adsorption is heterogeneous,
non-specific and non-uniform in nature. Kinetic studies were also
undertaken in terms of first order, second order, pseudo first
order, pseudo second order, Elovich, Boyd, and intra-particle
diffusion models. The results indicated that the data followed
pseudo second order model with surface adsorption and intraparticle
diffusion concurrently operating during the adsorbateadsorbent
interaction. The values of the thermodynamic
parameters computed from Van’t Hoff plot confirmed the
process to be endothermic and spontaneous in nature.
Treatment of Effluent from Granite Cutting Plant by Using Natural Adsorbents ...IJERD Editor
Granite cutting plant is one such industry that releases polluting and turbid effluent. The residue from all these processes is discharged with water as an effluent. The effluent mainly contains many solids that harm the environment. Hence it requires treatment techniques before disposal. Several conventional methods are available for removal of contaminants like coagulation, adsorption, polyelectrolyte methods and biological methods. Most of them are cost prohibitive. The reduction of solids concentration in the effluent before disposal by using the techniques, coagulation followed by adsorption using natural adsorbents, like rice husk carbon and saw dust carbon, in contrast to the usage of activated carbon as it is costly. From a local Granite cutting plant near Anantapur, the effluent is collected and its physico-chemical characteristics are estimated and found to be pH(7.5), TS(4240mg/l), TSS(21560mg/l), TDS(12373mg/l).Effluent obtained is subjected to coagulation by potash alum followed by adsorption using saw dust carbon and rice husk carbon.
Comparative potential of black tea leaves waste to granular activated carbonGJESM Publication
The adsorption properties and mechanics of selected endocrine disrupting compounds; 17 β-estradiol, 17 α – ethinylestradiol and bisphenol A on locally available black tea leaves waste and granular activated carbon were investigated. The results obtained indicated that the kinetics of adsorption were pH, adsorbent dose, contact time and temperature dependent with equilibrium being reached at 20 to 40 minutes for tea leaves waste and 40 to 60 minutes for granular activated compound. Maximum adsorption capacities of 3.46, 2.44 and 18.35 mg/g were achieved for tea leaves waste compared to granular activated compound capacities of 4.01, 2.97 and 16.26 mg/g for 17 β- estradiol, 17 α-ethinylestradiol and bisphenol A respectively. Tea leaves waste adsorption followed pseudo-first order kinetics while granular activated compound fitted better to the pseudo-second order kinetic model. The experimental isotherm data for both tea leaves waste and granular activated compound showed a good fit to the Langmuir, Freundlich and Temkin isotherm models with the Langmuir model showing the best fit. The thermodynamic and kinetic data for the adsorption indicated that the adsorption process for tea leaves waste was predominantly by physical adsorption while the granular activated compound adsorption was more chemical in nature. The results have demonstrated the potential of waste tea leaves for the adsorptive removal of endocrine disrupting compounds from water.
Keywords
FEASIBILITY STUDY OF TREATMENT OF EFFLUENT FROM A BULK DRUG MANUFACTURING IND...Journal For Research
A study has been carried out on aerobic biological treatment of a bulk drug industrial effluent which is highly acidic in nature and shows high value of BOD5 (≈ 36000 mg/l), COD (≈ 84000 mg/l). Chemical treatment conducted for neutralizing the pH followed by biological treatment using a lab-scale reactor with acclimatized bacterial consortia isolated from natural soil has confirmed its feasibility for biological treatment. About 99% removal of COD from starting value of around 8000 mg/l has been achieved. The COD value in different hydraulic retention time (HRT) has been brought down to less than 100 mg/l in treated effluent, showing high removal of dissolved organics by aerobic biological treatment.
Optimization of Na-Alginate Immobilization Method for Sulfide Oxidation Using...Premier Publishers
The study was aimed to investigate the optimization of Na-alginate immobilization method for biological sulfide oxidation process using an immobilized Thiobacillus species and the effects of four factors including Na-alginate concentration, CaCl2 concentration, agitation speed and amount of inoculum on sulfide conversion. The strength of sodium-alginate immobilization method for Thiobacillus species was evaluated. For this purpose, experiments were designed by a central composite design (CCD) and results were optimized by using response surface methodology (RSM). Design of experiments (DOE) was used to model and optimize the operational conditions. The central composite design (CCD) was very good for the optimization of variables; the R2 value for the developed model was 0.91. The results and analysis showed the optimized values for the sulfide oxidation. 95% Sulfide oxidation was achieved with optimized values. Beside this a useful by- product was produced from waste effluents.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Fertilizer plant waste carbon slurry has been investigated after some processing as an adsorbent for the removal of dyes and phenols using columns. The results show that the carbonaceous adsorbent prepared from carbon slurry being porous and having appreciable surface area (380 m2/g) can remove dyes both cationic (meldola blue, methylene blue, chrysoidine G, crystal violet) as well as anionic (ethyl orange, metanil yellow, acid blue 113), and phenols (phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol) fruitfully from water. The column type continuous flow operations were used to obtain the breakthrough curves. The breakthrough capacity, exhaustion capacity and degree of column utilization were evaluated from the plots. The results shows that the degree of column utilization for dyes lies in the range 60 to 76% while for phenols was in the range 53-58%. The exhaustion capacities were quite high as compared to the breakthrough capacities and were found to be 217, 211, 104, 126, 233, 248, 267 mg/g for meldola blue, crystal violet, chrysoidine G, methylene blue, ethyl orange, metanil yellow, acid blue 113, respectively and 25.6, 72.2, 82.2 and 197.3 mg/g for phenol, 2-chlorophenol, 4-chlorophenol and 2,4-dichlorophenol, respectively
ABSTRACT- Tagetes erecta L. was raised in pots containing soil treated with various concentrations of Pb(NO3)2 (500, 1000, 1500, 2000 and 2500mg/kg). At maturity plants were separated into root, stem, leaves and inflorescence and lead accumulated in each part was quantified. The effects of lead accumulation on growth was analyzed by the measurement of various growth parameters like root and shoot length, fresh and dry weight of root and shoot and total leaf area per plant. Moreover effect of lead accumulation on biochemical parameters was checked by quantitative estimation of various biochemical parameters like chlorophyll, total protein, free amino acids, total sugar, reducing sugar and starch. Results showed that there is no remarkable negative effect of accumulation of lead on the morphological growth of the plant. Biochemical analysis showed that amount of total protein continuously decreased whereas that of free amino acids continuously increased with increasing concentrations of lead. Amount of chlorophyll, total sugar, reducing sugar and starch contents continuously increased till mid-level i.e., Pb 1500 mg/kg and then continuously decreased at higher concentrations. Results of quantitative estimation of Pb in root, stem, leaves and inflorescence showed that roots accumulated highest amount of Pb followed by stem and leaves, whereas inflorescence contained least amount of Pb.
Key-words- Lead (Pb), Heavy metal, Tagetes erecta L., Accumulation, Phytoremediation
Batch adsorption experiments were carried out for
the adsorption of cationic dye from aqueous solution onto
composite activated carbon. The composite activated carbon was
prepared from brewer’s spent grain and sea bean shell at a ratio
of 1:1. The equilibrium studies were done at different
concentrations and temperatures. The equilibrium data were
fitted to Langmuir, Freundlich, Dubinin-Radushkevich, and
Temkin isotherm models. The results showed that both Lagmuir
and Freundlich isotherm model fitted the data reasonably well
but Freundlich isotherm fitted better in the temperature range
studied. This confirmed that the adsorption is heterogeneous,
non-specific and non-uniform in nature. Kinetic studies were also
undertaken in terms of first order, second order, pseudo first
order, pseudo second order, Elovich, Boyd, and intra-particle
diffusion models. The results indicated that the data followed
pseudo second order model with surface adsorption and intraparticle
diffusion concurrently operating during the adsorbateadsorbent
interaction. The values of the thermodynamic
parameters computed from Van’t Hoff plot confirmed the
process to be endothermic and spontaneous in nature.
Treatment of Effluent from Granite Cutting Plant by Using Natural Adsorbents ...IJERD Editor
Granite cutting plant is one such industry that releases polluting and turbid effluent. The residue from all these processes is discharged with water as an effluent. The effluent mainly contains many solids that harm the environment. Hence it requires treatment techniques before disposal. Several conventional methods are available for removal of contaminants like coagulation, adsorption, polyelectrolyte methods and biological methods. Most of them are cost prohibitive. The reduction of solids concentration in the effluent before disposal by using the techniques, coagulation followed by adsorption using natural adsorbents, like rice husk carbon and saw dust carbon, in contrast to the usage of activated carbon as it is costly. From a local Granite cutting plant near Anantapur, the effluent is collected and its physico-chemical characteristics are estimated and found to be pH(7.5), TS(4240mg/l), TSS(21560mg/l), TDS(12373mg/l).Effluent obtained is subjected to coagulation by potash alum followed by adsorption using saw dust carbon and rice husk carbon.
Comparative potential of black tea leaves waste to granular activated carbonGJESM Publication
The adsorption properties and mechanics of selected endocrine disrupting compounds; 17 β-estradiol, 17 α – ethinylestradiol and bisphenol A on locally available black tea leaves waste and granular activated carbon were investigated. The results obtained indicated that the kinetics of adsorption were pH, adsorbent dose, contact time and temperature dependent with equilibrium being reached at 20 to 40 minutes for tea leaves waste and 40 to 60 minutes for granular activated compound. Maximum adsorption capacities of 3.46, 2.44 and 18.35 mg/g were achieved for tea leaves waste compared to granular activated compound capacities of 4.01, 2.97 and 16.26 mg/g for 17 β- estradiol, 17 α-ethinylestradiol and bisphenol A respectively. Tea leaves waste adsorption followed pseudo-first order kinetics while granular activated compound fitted better to the pseudo-second order kinetic model. The experimental isotherm data for both tea leaves waste and granular activated compound showed a good fit to the Langmuir, Freundlich and Temkin isotherm models with the Langmuir model showing the best fit. The thermodynamic and kinetic data for the adsorption indicated that the adsorption process for tea leaves waste was predominantly by physical adsorption while the granular activated compound adsorption was more chemical in nature. The results have demonstrated the potential of waste tea leaves for the adsorptive removal of endocrine disrupting compounds from water.
Keywords
FEASIBILITY STUDY OF TREATMENT OF EFFLUENT FROM A BULK DRUG MANUFACTURING IND...Journal For Research
A study has been carried out on aerobic biological treatment of a bulk drug industrial effluent which is highly acidic in nature and shows high value of BOD5 (≈ 36000 mg/l), COD (≈ 84000 mg/l). Chemical treatment conducted for neutralizing the pH followed by biological treatment using a lab-scale reactor with acclimatized bacterial consortia isolated from natural soil has confirmed its feasibility for biological treatment. About 99% removal of COD from starting value of around 8000 mg/l has been achieved. The COD value in different hydraulic retention time (HRT) has been brought down to less than 100 mg/l in treated effluent, showing high removal of dissolved organics by aerobic biological treatment.
Optimization of Na-Alginate Immobilization Method for Sulfide Oxidation Using...Premier Publishers
The study was aimed to investigate the optimization of Na-alginate immobilization method for biological sulfide oxidation process using an immobilized Thiobacillus species and the effects of four factors including Na-alginate concentration, CaCl2 concentration, agitation speed and amount of inoculum on sulfide conversion. The strength of sodium-alginate immobilization method for Thiobacillus species was evaluated. For this purpose, experiments were designed by a central composite design (CCD) and results were optimized by using response surface methodology (RSM). Design of experiments (DOE) was used to model and optimize the operational conditions. The central composite design (CCD) was very good for the optimization of variables; the R2 value for the developed model was 0.91. The results and analysis showed the optimized values for the sulfide oxidation. 95% Sulfide oxidation was achieved with optimized values. Beside this a useful by- product was produced from waste effluents.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Distillery Wastewater Decontamination by the Fenton Advanced Oxidation MethodIJRES Journal
This study evaluated the effect of Fenton advanced oxidation process on the treatment of an industrial wastewater (distillery). The comparison of the effects of Fe2+ loadings, H2O2 dosages (2%(v/v)and 4%(v/v)), reaction temperature and reaction time, established optimum efficiency in terms of BOD and COD reductions. The best operating conditions for the treatment of the distillery wastewater containing 43.85 mg/L BOD concentration and 274.28 mg/L COD concentration in the raw effluent was 2% H2O2 dosage at constant loadings of Fe2+ (1.5 g), 80 oC pretreatment temperature, and 1 h reaction time. At this optimized condition, the BOD content reduced to about 35 mg/L (about 21% removal) and COD content reduced to about 53 mg/L (about 81% removal). There was a complete removal of the initial colour present in the wastewater after the treatment process. The process proved the ability to effectively reduce the COD content which when high in industrial wastewaters can lead to serious impacts to the environment.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Mass Transfer, Kinetic, Equilibrium, and Thermodynamic Study on Removal of Di...Ratnakaram Venkata Nadh
Three distinct agricultural waste materials, viz., casuarina fruit powder (CFP), sorghum stem powder
(SSP), and banana stem powder (BSP) were used as low-cost adsorbents for the removal of toxic lead(II)
from aqueous solutions. Acid treated adsorbents were characterized by scanning electron microscopy (SEM),
energy-dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR). The
effects of parameters like adsorbent dose, pH, temperature, initial metal ion concentration, and time of
adsorption on the removal of Pb(II) were analyzed for each adsorbent individually and the efficiency order
was BSP > SSP > CFP. Based on the extent of compatibility to Freundlich/Langmuir/Dubinin–Radushkevich/
Temkin adsorption isotherms and different models (pseudo-first and second order, Boyd, Weber’s, and
Elovich), chemisorption primarily involved in the case of BSP and SSP, whereas simultaneous occurrence of
chemisorption and physisorption was proposed in the case of CFP correlating with the thermodynamic study
results conducted at different temperatures. Based on the observations, it was proposed that three kinetic
stages involve in the adsorption process, viz., diffusion of sorbate to sorbent, intra particle diffusion, and then
establishment of equilibrium. These adsorbents have a promising role towards the removal of Pb(II) from
industrial wastewater to contribute environmental protection
Extraction of selected rare earth elements from anthracite acid mine drainage...GuanrongSong1
Rare earth elements (REEs) are valuable raw materials which are in great demand in modern high
technology industries. Developing methods to produce/recover REEs from waste is significant to the
national security of any developed country. This study was focused on investigating the use of supercritical
CO2 (sCO2) to extract REEs from anthracite acid mine drainage (AMD). Four different mine
drainage water source locations at Blaschak Coal Corp. in Pennsylvania, USA were selected for sample
collection. An extraction process was developed and demonstrated for two of those water sources
containing the highest concentration of REEs. A method involving metal ion coagulation, their dissolution
from the sludge into a concentrated aqueous HNO3 solution, complexation with organic ligands and
sCO2 extraction was developed to recover REEs from AMD. Specifically, sodium aluminate (NaAlO2) was
used as the coagulant to concentrate REEs from the AMD into a solid precipitate. Consequently, over 99%
of the REEs in AMD is concentrated in the remaining sludge. During the coagulation process, the effects
of pH and NaAlO2 concentration on REE precipitation were investigated. Fuming nitric acid (HNO3) was
used to digest the pre-concentrated sludge and tributyl phosphate (TBP) was used to form REE/TBP/
HNO3, a non-polar complex with selected REEs, specifically, cerium (Ce), lanthanum (La) and neodymium
(Nd). HNO3 concentration and organic/aqueous phase ratio were considered as the variables to improve
complexation efficiency. Dynamic extraction experiments using sCO2 and REE/TBP/HNO3 solutions were
then conducted at optimal conditions of 60 C and 20 MPa. The overall REE extraction efficiencies are
found to increase with the atomic number of the REE. As a result, the average overall REE extraction
efficiencies of 41.8%, 40.1% and 58.2% for Ce, La and Nd, respectively, are obtained. The potential improvements
in the overall extraction efficiency are also discussed.
STUDY ON EFFECT OF SOIL WASHING WITH DIFFERENT WASHING CYCLES ON PARTICLE SIZ...ijsrd.com
Soil contamination by heavy metals is a major problem at many contaminated sites now a day. According to EPA’s list of priority pollutants cadmium, chromium, copper, lead, mercury, nickel, and zinc are the most hazardous heavy metals found at many soil contaminated sites. Many techniques are employed for the decontamination of soils. This consists of various physiochemical as well as biological methods. Among these process soil washing is a physiochemical method, which has a very high efficiency for heavy metal removal from contaminated soils. It is a simple, ex situ remediation technology. In this process by the addition of washing water, heavy metals can be transferred from the degraded sediment to wash solution. This process can be enhanced by addition of acid washing, chelating agents or surfactants. Particle size always plays an important role in the removal of heavy metals. In this research paper an attempt has made to soil washing technology for removal of Pb and Cr from contaminated soil with the help of different combination of EDTA and DI water cycle. Another attempt has also made to find out the effect of particle size i.e. soil, silt and clay on the soil washing.
Focused researcher and environmental consultant with a thorough approach to groundwater, wastewater and soil treatment processes. I am based in Dublin, but engaged in a number of water treatment projects in South Asia. I take pleasure in solving green technology challenges and brainstorming over new concepts. I enjoy drafting technical documents- proposals, reports, ppt and articles. I am proficient in various graphical and statistical software packages.
Currently I am doing a Masters in Natural Resource Economics and Policy from NUI Galway, Ireland. Econometric modelling, data analysis and cost-benefit evaluations are the topics that I am most curious about. I am always looking for new opportunities in the field of environmental management involving stakeholder engagement.
Focused researcher and environmental consultant with a thorough approach to groundwater, wastewater and soil treatment processes. I am based in Dublin, but engaged in a number of water treatment projects in South Asia. I take pleasure in solving green technology challenges and brainstorming over new concepts. I enjoy drafting technical documents- proposals, reports, ppt and articles. I am proficient in various graphical and statistical software packages.
Currently I am doing a Masters in Natural Resource Economics and Policy from NUI Galway, Ireland. Econometric modelling, data analysis and cost-benefit evaluations are the topics that I am most curious about. I am always looking for new opportunities in the field of environmental management involving stakeholder engagement.
UNDERSTANDING WHAT GREEN WASHING IS!.pdfJulietMogola
Many companies today use green washing to lure the public into thinking they are conserving the environment but in real sense they are doing more harm. There have been such several cases from very big companies here in Kenya and also globally. This ranges from various sectors from manufacturing and goes to consumer products. Educating people on greenwashing will enable people to make better choices based on their analysis and not on what they see on marketing sites.
Artificial Reefs by Kuddle Life Foundation - May 2024punit537210
Situated in Pondicherry, India, Kuddle Life Foundation is a charitable, non-profit and non-governmental organization (NGO) dedicated to improving the living standards of coastal communities and simultaneously placing a strong emphasis on the protection of marine ecosystems.
One of the key areas we work in is Artificial Reefs. This presentation captures our journey so far and our learnings. We hope you get as excited about marine conservation and artificial reefs as we are.
Please visit our website: https://kuddlelife.org
Our Instagram channel:
@kuddlelifefoundation
Our Linkedin Page:
https://www.linkedin.com/company/kuddlelifefoundation/
and write to us if you have any questions:
info@kuddlelife.org
"Understanding the Carbon Cycle: Processes, Human Impacts, and Strategies for...MMariSelvam4
The carbon cycle is a critical component of Earth's environmental system, governing the movement and transformation of carbon through various reservoirs, including the atmosphere, oceans, soil, and living organisms. This complex cycle involves several key processes such as photosynthesis, respiration, decomposition, and carbon sequestration, each contributing to the regulation of carbon levels on the planet.
Human activities, particularly fossil fuel combustion and deforestation, have significantly altered the natural carbon cycle, leading to increased atmospheric carbon dioxide concentrations and driving climate change. Understanding the intricacies of the carbon cycle is essential for assessing the impacts of these changes and developing effective mitigation strategies.
By studying the carbon cycle, scientists can identify carbon sources and sinks, measure carbon fluxes, and predict future trends. This knowledge is crucial for crafting policies aimed at reducing carbon emissions, enhancing carbon storage, and promoting sustainable practices. The carbon cycle's interplay with climate systems, ecosystems, and human activities underscores its importance in maintaining a stable and healthy planet.
In-depth exploration of the carbon cycle reveals the delicate balance required to sustain life and the urgent need to address anthropogenic influences. Through research, education, and policy, we can work towards restoring equilibrium in the carbon cycle and ensuring a sustainable future for generations to come.
Characterization and the Kinetics of drying at the drying oven and with micro...Open Access Research Paper
The objective of this work is to contribute to valorization de Nephelium lappaceum by the characterization of kinetics of drying of seeds of Nephelium lappaceum. The seeds were dehydrated until a constant mass respectively in a drying oven and a microwawe oven. The temperatures and the powers of drying are respectively: 50, 60 and 70°C and 140, 280 and 420 W. The results show that the curves of drying of seeds of Nephelium lappaceum do not present a phase of constant kinetics. The coefficients of diffusion vary between 2.09.10-8 to 2.98. 10-8m-2/s in the interval of 50°C at 70°C and between 4.83×10-07 at 9.04×10-07 m-8/s for the powers going of 140 W with 420 W the relation between Arrhenius and a value of energy of activation of 16.49 kJ. mol-1 expressed the effect of the temperature on effective diffusivity.
Willie Nelson Net Worth: A Journey Through Music, Movies, and Business Venturesgreendigital
Willie Nelson is a name that resonates within the world of music and entertainment. Known for his unique voice, and masterful guitar skills. and an extraordinary career spanning several decades. Nelson has become a legend in the country music scene. But, his influence extends far beyond the realm of music. with ventures in acting, writing, activism, and business. This comprehensive article delves into Willie Nelson net worth. exploring the various facets of his career that have contributed to his large fortune.
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Introduction
Willie Nelson net worth is a testament to his enduring influence and success in many fields. Born on April 29, 1933, in Abbott, Texas. Nelson's journey from a humble beginning to becoming one of the most iconic figures in American music is nothing short of inspirational. His net worth, which estimated to be around $25 million as of 2024. reflects a career that is as diverse as it is prolific.
Early Life and Musical Beginnings
Humble Origins
Willie Hugh Nelson was born during the Great Depression. a time of significant economic hardship in the United States. Raised by his grandparents. Nelson found solace and inspiration in music from an early age. His grandmother taught him to play the guitar. setting the stage for what would become an illustrious career.
First Steps in Music
Nelson's initial foray into the music industry was fraught with challenges. He moved to Nashville, Tennessee, to pursue his dreams, but success did not come . Working as a songwriter, Nelson penned hits for other artists. which helped him gain a foothold in the competitive music scene. His songwriting skills contributed to his early earnings. laying the foundation for his net worth.
Rise to Stardom
Breakthrough Albums
The 1970s marked a turning point in Willie Nelson's career. His albums "Shotgun Willie" (1973), "Red Headed Stranger" (1975). and "Stardust" (1978) received critical acclaim and commercial success. These albums not only solidified his position in the country music genre. but also introduced his music to a broader audience. The success of these albums played a crucial role in boosting Willie Nelson net worth.
Iconic Songs
Willie Nelson net worth is also attributed to his extensive catalog of hit songs. Tracks like "Blue Eyes Crying in the Rain," "On the Road Again," and "Always on My Mind" have become timeless classics. These songs have not only earned Nelson large royalties but have also ensured his continued relevance in the music industry.
Acting and Film Career
Hollywood Ventures
In addition to his music career, Willie Nelson has also made a mark in Hollywood. His distinctive personality and on-screen presence have landed him roles in several films and television shows. Notable appearances include roles in "The Electric Horseman" (1979), "Honeysuckle Rose" (1980), and "Barbarosa" (1982). These acting gigs have added a significant amount to Willie Nelson net worth.
Television Appearances
Nelson's char
Ammonium-based deep eutectic solvents as novel soil washing agent for lead removal_cej
1. Ammonium-based deep eutectic solvents as novel soil washing agent
for lead removal
Soumyadeep Mukhopadhyay a,⇑
, Sumona Mukherjee a
, Nor Farihah Adnan a
, Adeeb Hayyan a,b
,
Maan Hayyan b,c
, Mohd Ali Hashim a,b
, Bhaskar Sen Gupta d
a
Department of Chemical Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
b
University of Malaya Centre for Ionic Liquids, University of Malaya, 50603 Kuala Lumpur, Malaysia
c
Department of Civil Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia
d
Water Academy, Institute of Infrastructure and Environment, Heriot-Watt University, Edinburgh Campus, Scotland EH14 4AS, United Kingdom
h i g h l i g h t s
Deep eutectic solvents (DESs) are
used for the first time for soil
remediation.
Saponins are used to enhance DESs
performances for lead (Pb) removal.
Natural DESs formed with choline
chloride and fructose/sucrose
examined in details.
Up to 72% Pb was removed with a
combination of 40% DES-fructose and
1% saponin.
Soil corrosion by DES washing is
negligible.
g r a p h i c a l a b s t r a c t
a r t i c l e i n f o
Article history:
Received 1 December 2015
Received in revised form 8 February 2016
Accepted 9 February 2016
Available online 15 February 2016
Keywords:
Soil washing
Deep eutectic solvents
Sapindus mukorossi
Lead
Fructose-based DES
Choline chloride
a b s t r a c t
Deep eutectic solvents (DESs) are a new class of biodegradable and low cost solvents analogous to ionic
liquids. In this study, DESs have been used to remove lead from a landfill soil for the first time. The DESs
used in this study were prepared by mixing choline chloride, a quaternary ammonium salt with different
hydrogen bond donors such as fructose, sucrose, glycerol and ethylene glycol. A natural biodegradable
surfactant saponin extracted from soapnut fruit pericarp, was mixed with DESs to enhance their effi-
ciency. The 10% solution of fruit-based DESs containing fructose and sucrose demonstrated lead removal
of about 31% and 25% respectively, which increased on addition of saponin. Up to 72% Pb could be
removed with a combination of 40% fructose-based DES and 1% saponin or 10% fructose-based DES
and 2% saponin. For synthetic DESs containing glycerol and ethylene glycol, saponin addition resulted
in marked improvement of up to 54%. Mildly alkaline DESs supplied H+
acting as Lewis acid which
replaced the lead cations from the organic carbon electron donors. Slightly alkaline DESs performed bet-
ter when mixed with acidic saponin solution which supplied H+
. This study will open up new possibilities
into the application of natural compound based DESs for soil remediation.
Ó 2016 Elsevier B.V. All rights reserved.
1. Introduction
Soil and groundwater pollution affects millions of lives around
the world [1]. Modern industrial, agricultural and mining activities
affect soil by releasing various contaminants such as organics, oils
http://dx.doi.org/10.1016/j.cej.2016.02.030
1385-8947/Ó 2016 Elsevier B.V. All rights reserved.
⇑ Corresponding author. Tel.: +60 166306998.
E-mail address: soumya_m@ymail.com (S. Mukhopadhyay).
Chemical Engineering Journal 294 (2016) 316–322
Contents lists available at ScienceDirect
Chemical Engineering Journal
journal homepage: www.elsevier.com/locate/cej
2. and heavy metals which eventually leach to the aquifer. Lead (Pb)
is one of the heavy metals which has been released in the soil envi-
ronment in large amount [2]. As a consequence, soil contains lead
concentrations less than 50 mg kgÀ1
, but in many urban areas lead
levels exceed 200 mg kgÀ1
. The USEPA’s standard for lead in bare
soil in play areas is 400 mg kgÀ1
by weight and 1200 mg kgÀ1
for
non-play areas [3]. Toxicity of Pb is well researched [4]. Therefore
excess Pb needs to be removed from affected soils for reducing
public health risk. Washing of soil contaminated with heavy metals
and organics is a widely accepted practice [5–8] and saponin, a
plant based surfactant has been effectively used for contaminant
removal from soil [9–11]. Saponin (SN) is environment friendly
and has been used as detergent and medicine for many decades
[12]. It can be extracted from the fruit pericarp of Sapindus muko-
rossi which contains natural surfactant triterpenoidal saponins viz
oleanane, dammarane and tirucullane [12].
Ionic liquids (ILs) have emerged as potentially versatile solvents
for various applications including those for liquid extraction pro-
cesses [13–17]. Properties of ILs include high thermal and electro-
chemical stabilities, wide liquid phase range and high ionic
conductivity [17]. Recently, a new class of ILs analogue, namely
deep eutectic solvents (DESs) which consist of a mixture of two
or more compounds that have melting points lower than that of
either of its components [15]. DESs share many physical properties
with ILs and can be synthesized by mixing a hydrogen bond donor
with a salt [18]. The charge delocalisation occurring through
hydrogen bonding between the halide anion and the hydrogen
bond donor moiety is responsible for the decrease in the freezing
point of the mixture relative to the melting points of the individual
components [19]. This significant depression of the freezing point
stems from an interaction between the halide anion of the salt
and the hydrogen bond donor (HBD) component [15,20]. Choline
chloride has been used earlier as HBD [21] to synthesize DESs. Nat-
ural DESs or NADESs, a class of DESs obtained from mixing natural
plant derivatives such as glucose, fructose and citric acid with cho-
line chloride have been described earlier [22–24]. The NMR data
showed that hydrogen bonding was the key to the formation of
NADES, allowing the creation of supramolecular structures
between the components.
Toxicity aspects of ammonium based DESs with HBD e.g. glyc-
erine, ethylene glycol, triethylene glycol and urea have been stud-
ied through in vitro and in vivo studies and they were found to be
less toxic than ionic liquids [25,26]. Choline chloride: glucose and
choline chloride: glycerol displayed low cytotoxic effects [27].
Recently, ethylene glycol and glycerol DESs with choline chloride
were found to be biodegradable under lower concentrations [28].
DESs have attracted attention in the fields of chemical synthe-
sis, metal-catalyzed organic reactions, biological catalysis [29],
lubrication [30], electrochemical processes [31], production and
purification of biodiesel [15,18], separation of aliphatic and
Table 1
List of different DESs and their pH.
1st component
(quaternary
ammonium salt)
2nd component
(HBD)
3rd
component
Ratio of components
(1:2:3)
pH of DES pH (10 mL DES + 1 g soil) pH (5 mL DES-5 mL
1% SN + 1 g soil)
DES-Fr Choline chloride Fructose Water 5:2:5 6.26 7.28 4.45
DES-Su Choline chloride Sucrose Water 4:1:4 6.76 6.86 4.41
DES-Gly Choline chloride Glycerol Water 1:2:1 8.10 6.99 4.49
DES-EtGl Choline chloride Ethylene glycol Water 1:3:1 8.12 7.52 4.58
Fig. 1. Structure of different DESs used in the study.
S. Mukhopadhyay et al. / Chemical Engineering Journal 294 (2016) 316–322 317
3. aromatics [32]. However, DESs have never been used as washing
agent for contaminant removal from soil matrices. Therefore, this
study used a group of ammonium-based DES for soil washing. Dif-
ferent HBDs were used to prepare NADES such as fructose, sucrose
and glycerol. NADES and ethylene glycol-based DES (DES-EtGl)
have been combined with natural surfactant (saponin) for investi-
gation of their synergistic effect on the process, adding a new
dimension to the study.
2. Materials and methods
A composite soil sample was collected from Jeram Sanitary
Landfill (JSL) in Selangor, Malaysia. JSL receives waste from seven
major municipalities, mostly from Kuala Lumpur and Selangor
Municipality. The soil was dried in an oven overnight at 105 °C fol-
lowing the protocol presented by Roy et al. [33] and was crushed
and passed through a 2 mm sieve. It was classified according to
USDA soil classification. The soil pH was measured by USEPA
SW-846 Method 9045D while Eh was measured by an ORP elec-
trode following ASTM Method D 1498-93 after preparing the sam-
ple by USEPA Method 9045 for soil samples as suggested in SW-
846 series. The soil was spiked with1000 mg LÀ1
concentrations
of Pb in Pb(NO3)2 solution at room temperature by mixing it for
7 days at weight: volume ratio of 3:2, air dried at 25 °C for 24 h
and sieved through 2 mm mesh screen. It was digested following
USEPA Method 3050B in order to measure metal contents by ICP-
OES (Perkin–Elmer Optima 7000DV) using Perkin–Elmer multi-
metal standard solutions. All the samples were analysed in tripli-
cate and the results were reproducible within ±3.5%. A set of 4 DESs
were used for the preliminary study. The compositions of these
DESs are given in Table 1 and their structures are shown in
Fig. 1. All chemicals used for DESs’ preparation were dried at
60 °C under vacuum. A glass jacketed vessel with a magnetic stirrer
was used to prepare DES samples at 70 °C and stirrer speed of
350 rpm for 3 h mixing time. The DES preparation was carried
out in a fume hood. Soapnut solution of 1% concentration (w/w)
was used in combination with the 4 DESs for Pb desorption from
the soil and were compared against water blank. Saponin was
extracted from the soapnut fruit pericarp by water and the saponin
concentration was measured by UV–Visible spectra to be 65% fol-
lowing Roy et al. [33]. The pH of 1% soapnut solution was 4.44
and surface tension was 40 mN mÀ1
measured by a ring type sur-
face tensiometer (Fisher Scientific Manual Model 20).
Batch tests were conducted in 15 mL test tubes. For each exper-
iment, 1 gof soil was washed with 5 mL of wash solution (DESs and
DES–saponin mixtures) of different concentrations as shown in
Fig. 2. The test tubes were shaken in an orbital shaker in horizontal
position for 4 h. Wash solutions were then centrifuged, filtered and
preserved with 1 drop of nitric acid for ICP analysis for Pb
concentration.
XRD spectroscopy and SEM were used to inspect the damage to
the mineral structure of soil. 10 g of soil was washed with 100 mL of
10% DES-EtGl and mixture of 10% DES-EtGl and 1% saponin for 4 h.
Following this, they were filtered and the soil samples were dried at
45 °C. Along with unwashed soil sample, they were subjected to
XRD and SEM analysis to check for any mineralogical change of
the soil. XRD analysis was performed by a Panalytical Empyrean
diffractometer using Highscore Plus software and SEM was per-
formed using a Zeiss Auriga 39-22 SEM under accelerating voltage
of 1.00 kV, System Vacuum = 2.35eÀ006 mbar À 1.86eÀ006 mbar.
Table 2
Characterisation of the contaminated soil.
mm %
(a) Size distribution of soil particles
Gravel/rock 2 5.750
Very coarse sand 0.85 x 2 17.180
Coarse sand 0.71 x 0.85 3.582
Medium sand 0.25 x 0.71 36.951
Fine sand 0.045 x 0.25 34.140
Silt 0.045 2.397
(b) Physical characteristics
Moisture content (% wt) 3.60
Loss by ignition (% wt) 1.21
Density (kg LÀ1
) 2.52
pH 3.45
ORP (mV) 333
EC (mS cmÀ1
) 8.25
(c) Metal content (mg kgÀ1
)
Pb 1500
Al 11893.94
Fe 1000
Mg 464.393
Ca 220.758
Na 71.960
Mn 42.121
Zn 10.303
As 6.771
Fig. 2. Lead removal by DESs, DES+ saponin mixtures, water and saponin.
318 S. Mukhopadhyay et al. / Chemical Engineering Journal 294 (2016) 316–322
4. Fig. 3. (a) Variation of DES concentration at 1% saponin concentration and (b) variation of saponin concentration at 10% DES concentration.
Fig. 4. FTIR spectra of DES glucose before and after soil washing.
S. Mukhopadhyay et al. / Chemical Engineering Journal 294 (2016) 316–322 319
5. 3. Results and discussion
3.1. Soil characterisation
Table 2 summarizes the characteristics of the soil, which was
classified as sandy soil following USDA soil classification. The soil
redox potential value of 333 mV made it slightly oxidized, indicat-
ing minor electron deficiency. The soil was blackish in colour signi-
fying presence of some organic matter which was supported by a
small ignition loss of 1.21%. The organic matter tends to act as an
electron donor and binds with the heavy metal cations i.e. lead
in this case. A moderately high electrical conductivity value of
8.25 mS/cm suggests presence of charged species in the soil matrix.
On acid digestion, the mineralogical metals were extracted and
Al, Mg and Fe were detected in high concentration. A background
concentration of 218 mg kgÀ1
Pb was measured in unspiked soil,
probably in mineralogical state. After spiking, the Pb content of soil
was found to be 1500 mg kgÀ1
which is present as the soil contam-
ination. The soil pH is 3.45 indicating acidic nature of the soil. Low
pH value of soil can be the result of rainwater leaching away basic
ions (calcium, magnesium, potassium and sodium) and formation
of carbon dioxide from decomposing organic matter and from root
respiration; dissolving in soil water to form a weak organic acid.
Therefore, the overall soil was found to have electron deficiency
in spite of presence of organic carbonaceous compounds, which
act as electron donor centres and bind readily with lead cations.
The success of lead extraction would depend upon the ability of
the washing agent to break the bond between organic carbon
and lead.
3.2. Pb removal by DESs and saponin
The Pb removal by a 10% solution of individual DESs in the
absence or presence of saponin has been shown in Fig. 2. Water
and 0.5% saponin solutions were used as blanks. The Pb was
strongly bound with soil organic carbon and water could remove
only up to 5% of Pb signifying the necessity of adding other extrac-
tants. A 1% soapnut removed up to about 31% Pb. A 10% solution of
DES-Fr showed the best performance in terms of Pb removal on its
own, removing up to 31% of Pb followed by 10% DES-Su (sucrose),
which removed 25.21% Pb from soil. DES-EtGl and DES-Gly, both at
10% concentration, did not show promising performance on their
own, removing only 6.55 and 3.44% Pb respectively. However, on
addition of saponin solution, their performances improved by a
large extent. For DES-Gly, lead removal ability enhanced up to
54% compared with 4% observed earlier on addition of 0.5% sapo-
nin. DES-EtGl is another notable case, which recorded an improve-
ment of 34% more than its previous result.
The Pb removal has a strong correlation with the pH of the solu-
tion, signifying a Lewis acid–base reaction. The slightly acidic DESs
i.e. DES-Fr and DES-Su could remove more Pb by attacking electron
rich organic carbon sites thereby releasing Pb2+
cations, than the
slightly alkaline DESs e.g. DES-Gly and DES-EtGl. In presence of
saponin solution which is also acidic, a number of factors come
into play that increased the Pb removal such as (a) lowering in
pH thereby supplying more H+
, (b) introduction of saponin result-
ing in micellar solubilisation of Pb2+
from soil particles (c) dilution
of DESs and introduction of more H2O molecules, which can act as
a media to leach out the already loosened Pb from soil surface.
Fig. 5. (a) XRD spectra and (b–d) SEM imagery of soil before and after washing with DES-EtGl and DES EtGl–soapnut mixture.
320 S. Mukhopadhyay et al. / Chemical Engineering Journal 294 (2016) 316–322
6. Fruit sugar based DESs such as DES-Fr and DES-Su were further
investigated with different concentrations in presence and absence
of saponin. Fig. 3(a) depicts the increase in Pb2+
removal when
DES-Fr and DES-Su concentrations are increased from 5% to 40%
both in absence of saponin and in presence of 1% saponin. Fig. 3
(b) clearly shows the increase in lead removal when saponin con-
centration was increased from 0.5% up to 2% in presence of 10%
solutions of DES-Fr and DES-Su without any exception. Therefore,
the general trend is that the performance of DESs as well as
DES–saponin mixtures improves with increasing the concentration
of any of them, thereby proving a direct relationship between the
activities of these two agents behind removal of Pb2+
.
These findings indicate that the soil washing by DESs and sapo-
nin solutions represent a Lewis acid–base interaction. While the
soil has a deficiency of electrons, the organic carbon produces elec-
tron donating points, thereby acting as an electron pair donating
Lewis base, attracting and bounding Pb2+
cations which act as Lewis
acid. Electron transfer reactions tend to occur through an adsorbed
layer [34]. The DESs used in this study had either acidic pH (e.g.
DES-Fr and DES-Su), or slightly alkaline pH (e.g. DES-Gly and
DES-EtGl). Therefore, when the acidic DESs i.e. DES-Fr and DES-
Su were added with the Pb2+
contaminated soil, H+
or H3O+
ions
were introduced, a powerful Lewis acid. The H+
ions attacked the
electron rich sites of the soil, mostly the organic carbon and com-
peted with the Pb2+
for electrons, thereby pulling them out of the
soil surface and attaching them with DES anions already present
in the solution. However, when the alkaline DES-Gly and DES-
EtGl were introduced into the system, H+
or H3O+
ions were not
supplied since they are alkaline in nature. Therefore, the Pb2+
-
removals were negligible for these two DESs. Following that, when
DESs were mixed with saponin, which is naturally acidic in nature,
more H+
or H3O+
ions were introduced in the system and all the
DESs demonstrated better performance. Saponin also contributed
by trapping the Pb2+
inside micelle. In earlier works, Song et al.
[35] suggested complexation of saponin molecule with heavy met-
als. However, the FTIR spectra in Fig. 4 do not detect any complex-
ation between DES-glucose, soapnut and Pb2+
. The FTIR spectra of
all the solutions give similar peaks and no shift of peaks could be
detected after introduction of Pb in the DES and DES–SN solutions.
Once the H+
or H3O+
ions sourced from the saponin solution com-
pete with the Pb2+
, loosening their bond, DES anions remove them
from the soil surface. The synergistic effect of saponin and DES
therefore improves the performance of the DES–saponin mixtures.
3.3. Damage of soil mineralogical structure
XRD spectra of Pb contaminated soil and the soils washed with
DES-EtGl as well as a mixture of DES-EtGl and saponin did not
detect any change in the location of the peaks (Fig. 5(a)). This indi-
cates that the soil minerals did not undergo corrosion or miner-
alogical changes when they were subjected to soil washing. Fig. 5
(b–d) shows the SEM micrographs of Pb contaminated soil, washed
with a mixture of DES-EtGl + saponin and a 10% DES-EtGl respec-
tively. Minor roughness of underlying soil surface can be noticed
for both DES + saponin and DES. However, no major corrosion
could be observed. Therefore, DESs can be safely used for soil
washing without destroying the soil texture.
4. Conclusion
This study demonstrates the suitability of using DESs for soil
washing purpose alongside saponin. The DESs and saponin
performed well when used as a mixture rather than on their
own, indicating a synergistic behaviour where they both contribute
towards Pb2+
removal from soil. The soil washing process repre-
sents a Lewis acid–base reaction and therefore pH of the wash
solution plays an important role. Micellar solubilisation by saponin
adds an edge to the process. Also, the process improves when the
concentrations of both DESs and saponin were increased. Pb2+
removal of above 72.65% was obtained while using 40% DES-Fr
and 1% saponin mixture and 72.54% Pb2+
was removed by 10%
DES-Fr and 2% saponin mixture. These results are promising and
demand further investigation into the application of DESs for soil
washing. The biological origin of natural deep eutectic solvents
and natural saponin make the process of soil washing promising
and sustainable.
Acknowledgements
University of Malaya, Centre for Ionic Liquids (UMCIL) and
University of Malaya Grant no: UM-QUB6A-2011 are duly
acknowledged. The authors will also acknowledge the contribution
of Assoc. Prof. Dr. Mohamed Elwathig Saeed Mirghani from IIUM
for the FTIR analysis.
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