This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid produ...This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid production carried out simultaneously because the auxiliary agents can be oxidized by bacteria and the oxidation products involve acid. The acid required for dissolving alkaline gangue during bacterial leaching is produced, and acid equilibrium is reached during the ore bio-leaching. The recovery of copper reaches more than 95%.展开更多
In view of the importance of solvent extraction of rare earth metals with the acidic organophosphorous reagent,the development of a chemically based model applicable to high concentration is desired.In the present stu...In view of the importance of solvent extraction of rare earth metals with the acidic organophosphorous reagent,the development of a chemically based model applicable to high concentration is desired.In the present study,the equilibrium distribution of dysprosium(Ⅲ)between an aqueous nitric acid solution and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A)was measured in the range of an initial aqueous dysprosium(Ⅲ)concentration from 1.0×10-3to 1.0×10-1kmol/m 3and PC88A concentration from 0.16 to 0.65 kmol/m3in Shellsol D70 as the diluent.The obtained data were analyzed using the chemically based model in order to correlate the equilibrium distribution ratios.In this model,dysprosium(Ⅲ)was assumed to be extracted with the PC88A dimer as a 1:3 complex,the activities were considered for the aqueous species,and the effective concentration of the PC88A dimer was calculated using Alstad's empirical equation.As a result,the apparent extraction equilibrium constant was determined to be 253(kmol·m- 3)-2with an excellent correlation between the experiment and calculation results in the wide range of the logarithm of the distribution ratio from-2 to 3.5.In conclusion,the methodology in this model would be effective for quantitative description of solvent extraction behavior of general rare earth elements as well as dysprosium.展开更多
In this paper,waste clay was cured with ethyl acetate to obtain treated clay(TC),which was modified with gallic acid to obtain a low-cost sorbent that was characterized by EDX,SEM,and FTIR analysis.Uranium(Ⅵ)adsorpti...In this paper,waste clay was cured with ethyl acetate to obtain treated clay(TC),which was modified with gallic acid to obtain a low-cost sorbent that was characterized by EDX,SEM,and FTIR analysis.Uranium(Ⅵ)adsorption was achieved using the batch adsorption method on the TC and gallic acid-modified treated clay(GMTC).The maximum uptakes of U(Ⅵ)on TC and GMTC were 37.2 and 193.0 mg/g,respectively.The U(Ⅵ)adsorption kinetics on the TC and GMTC sorbents were well-fitted by the pseudo-second-order mechanism,and the adsorption equilibrium followed the Langmuir model.The optimum parameters were applied to El Sela leach solution for uranium recovery.展开更多
The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kineti...The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.展开更多
1 INTRODUCTIONSince the invention of asymmetric membrane by Loeb and Sourirajan [1],membraneseparation processes have attracted considerable commercial interests.L-S membranesare generally prepared by phase inversion ...1 INTRODUCTIONSince the invention of asymmetric membrane by Loeb and Sourirajan [1],membraneseparation processes have attracted considerable commercial interests.L-S membranesare generally prepared by phase inversion techniques [2].The thermodynamic and kine-tic analyses of these processes could be expressed by means of semiempiricalmathematical models.Such thermodynamic work involves the construction of a com-plete phase diagram for the membrane formation system and the membrane structure.展开更多
Based on the kinetic equations and equilibrium constants,some mathematic models were developed for calculating peracetic acid(PAA)concentration,equilibrium conversion rate of hydrogen peroxide,etc.The effects of sever...Based on the kinetic equations and equilibrium constants,some mathematic models were developed for calculating peracetic acid(PAA)concentration,equilibrium conversion rate of hydrogen peroxide,etc.The effects of several parameters on PAA synthesis were investigated by experimentation and modeling.The equilibrium constants determined from the forward and reverse rate constants at 293,303,313 and 323 K were 2.91,2.81,2.72 and 2.63,respectively.The models could predict the values of equilibrium concentration of PAA with average relative deviation of less than 10%.Both of the experimental and model-calculated results demonstrated that temperature and catalyst loading were the most important factors affecting the rate of PAA synthesis,but high temperature led to the decrease of equilibrium concentration of PAA.According to the model,the reaction could achieve equilibrium within 24 h when operated at 303 K with 1%～1.5%(ω)sulfuric acid as catalyst.Additionally,when using anhydrous acetic acid and 30%hydrogen peroxide to prepare PAA,the volumetric ratio of the two solutions should be in the range of 1.2～1.5 in order to obtain the highest equilibrium concentration of PAA.This study can serve as a step towards the further optimization of PAA synthesis and some other related investigations.展开更多
Humic acid(HA)can adsorb onto mineral surfaces,modifying the physicochemical properties of the mineral.Therefore,understanding the sorption behavior of HA onto mineral surfaces is of particular interest,since the fate...Humic acid(HA)can adsorb onto mineral surfaces,modifying the physicochemical properties of the mineral.Therefore,understanding the sorption behavior of HA onto mineral surfaces is of particular interest,since the fate and transport of many organic and inorganic contaminants are highly correlated to HA adsorbed onto clay surfaces.Due to the extreme heterogeneity of HA,the extracted IHSS Leonardite humic acid(LHA)used in this work was fractionated using an ultrafiltration technique(UF)into different molecular size fractions(Fr1,>0.2μm;Fr2,0.2 pm-300,000 daltons;Fr3,300,000-50,000 daltons;Fr4,50,000-10,000 daltons;Fr5,10,000-1000 daltons).Equilibrium and the kinetics of LHA and fraction adsorption onto kaolinite and montmorillonite were investigated.The results demonstrated that the maximum adsorption capacity of LHA,Frl,Fr2,Fr3,Fr4,and Fr5 was 5.99,13.69,10.29,7.02,5.9&and 5.09 on kaolinite while it was 8.29,22.62,13.17,8.91,8.62,and 5.69 on montmorillonite,respectively.The adsorption equilibrium data showed that the adsorption behavior of LHA and its fractions could be described more practically by the Langmuir model than the Freundlich model.The rate of humic acid fraction adsorption onto clays increased with decreasing molecular size fraction and increasing carboxylic group content.Pseudo-first-and second-order models were used to assess the kinetic data and the rate constants.The results explained that LHA and its fractions adsorption on clay minerals conformed more to pseudosecondo rder.展开更多
The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extrac...The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extraction experiments in a single stage were performed from a synthetic solution of citric acid, with the typical concentration (10% w/v) observed in industrial fermented musts. Exploratory experiments were carried out using different organic phases in order to select the most suitable solvent phase to further continuous extraction tests in a mechanically agitated column. The selected organic phase composition was: Alamine? 336, ExxalTM 13 tridecyl alcohol, and the aliphatic diluent EscaidTM 110. Next, the effects of the contact time and of the concentrations of extractant and modifier on the citric acid extraction were studied. Among the investigated conditions, the best one was 10 minutes of contact time, 30% w/v of Alamine? 336, and 10% w/v of ExxalTM 13 tridecyl alcohol. For this condition, the equilibrium isotherm (28°C ± 2°C) was determined, and the equilibrium constant was calculated (36.8 (mol·L-1)-1.5). It was considered that trioctylamine and citric acid complexation reaction occurs mainly with non-dissociated citric acid form, because the aqueous feed solutions’ pH is lower than the citric acid pKa1. It was found that 1.5 molecules of the extractant, on average, are required to react with one citric acid molecule, which can indicate that reactions with different extractant/citric acid ratios occur simultaneously. Next, the rate constants for the direct and inverse reactions, 2.10 (mol·L-1)-1.5·s-1 and 5.69 × 10-2 s-1, respectively, were calculated. Coefficients of determination (R2) values higher than 0.93 were found in these calculations, suggesting that the results obtained using a computer modeling would be very close to those results obtained experimentally. Therefore, the present work provides data required to future modelling, design, and simulation of citric acid solvent extraction processes.展开更多
文摘This article reports the study on acid equilibrium during bioleaching of alkaline low-grade copper sulfide ore. Adding auxiliary agents 1# （sulfur） and 2# （pyrite） makes bacterial leaching of copper and acid production carried out simultaneously because the auxiliary agents can be oxidized by bacteria and the oxidation products involve acid. The acid required for dissolving alkaline gangue during bacterial leaching is produced, and acid equilibrium is reached during the ore bio-leaching. The recovery of copper reaches more than 95%.
基金the Japan Society for the Promotion of Science for supporting this fellowship work(No.07616)
文摘In view of the importance of solvent extraction of rare earth metals with the acidic organophosphorous reagent,the development of a chemically based model applicable to high concentration is desired.In the present study,the equilibrium distribution of dysprosium(Ⅲ)between an aqueous nitric acid solution and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC88A)was measured in the range of an initial aqueous dysprosium(Ⅲ)concentration from 1.0×10-3to 1.0×10-1kmol/m 3and PC88A concentration from 0.16 to 0.65 kmol/m3in Shellsol D70 as the diluent.The obtained data were analyzed using the chemically based model in order to correlate the equilibrium distribution ratios.In this model,dysprosium(Ⅲ)was assumed to be extracted with the PC88A dimer as a 1:3 complex,the activities were considered for the aqueous species,and the effective concentration of the PC88A dimer was calculated using Alstad's empirical equation.As a result,the apparent extraction equilibrium constant was determined to be 253(kmol·m- 3)-2with an excellent correlation between the experiment and calculation results in the wide range of the logarithm of the distribution ratio from-2 to 3.5.In conclusion,the methodology in this model would be effective for quantitative description of solvent extraction behavior of general rare earth elements as well as dysprosium.
文摘In this paper,waste clay was cured with ethyl acetate to obtain treated clay(TC),which was modified with gallic acid to obtain a low-cost sorbent that was characterized by EDX,SEM,and FTIR analysis.Uranium(Ⅵ)adsorption was achieved using the batch adsorption method on the TC and gallic acid-modified treated clay(GMTC).The maximum uptakes of U(Ⅵ)on TC and GMTC were 37.2 and 193.0 mg/g,respectively.The U(Ⅵ)adsorption kinetics on the TC and GMTC sorbents were well-fitted by the pseudo-second-order mechanism,and the adsorption equilibrium followed the Langmuir model.The optimum parameters were applied to El Sela leach solution for uranium recovery.
基金Supported by a grant from Tianji Coal Chemical Group Co.Ltd.(Project no.2012-1978)Shenzhen Batian Ecological Engineering Co.,Ltd.(Project no.2013-0909).
文摘The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.
文摘1 INTRODUCTIONSince the invention of asymmetric membrane by Loeb and Sourirajan [1],membraneseparation processes have attracted considerable commercial interests.L-S membranesare generally prepared by phase inversion techniques [2].The thermodynamic and kine-tic analyses of these processes could be expressed by means of semiempiricalmathematical models.Such thermodynamic work involves the construction of a com-plete phase diagram for the membrane formation system and the membrane structure.
基金the Shell Global Solutions International B.V.(No.0506HL04)
文摘Based on the kinetic equations and equilibrium constants,some mathematic models were developed for calculating peracetic acid(PAA)concentration,equilibrium conversion rate of hydrogen peroxide,etc.The effects of several parameters on PAA synthesis were investigated by experimentation and modeling.The equilibrium constants determined from the forward and reverse rate constants at 293,303,313 and 323 K were 2.91,2.81,2.72 and 2.63,respectively.The models could predict the values of equilibrium concentration of PAA with average relative deviation of less than 10%.Both of the experimental and model-calculated results demonstrated that temperature and catalyst loading were the most important factors affecting the rate of PAA synthesis,but high temperature led to the decrease of equilibrium concentration of PAA.According to the model,the reaction could achieve equilibrium within 24 h when operated at 303 K with 1%～1.5%(ω)sulfuric acid as catalyst.Additionally,when using anhydrous acetic acid and 30%hydrogen peroxide to prepare PAA,the volumetric ratio of the two solutions should be in the range of 1.2～1.5 in order to obtain the highest equilibrium concentration of PAA.This study can serve as a step towards the further optimization of PAA synthesis and some other related investigations.
基金funded by a Fulbright Visiting Scholar fellowship to Mohamed El-sayed and performed at South Dakota State University
文摘Humic acid(HA)can adsorb onto mineral surfaces,modifying the physicochemical properties of the mineral.Therefore,understanding the sorption behavior of HA onto mineral surfaces is of particular interest,since the fate and transport of many organic and inorganic contaminants are highly correlated to HA adsorbed onto clay surfaces.Due to the extreme heterogeneity of HA,the extracted IHSS Leonardite humic acid(LHA)used in this work was fractionated using an ultrafiltration technique(UF)into different molecular size fractions(Fr1,>0.2μm;Fr2,0.2 pm-300,000 daltons;Fr3,300,000-50,000 daltons;Fr4,50,000-10,000 daltons;Fr5,10,000-1000 daltons).Equilibrium and the kinetics of LHA and fraction adsorption onto kaolinite and montmorillonite were investigated.The results demonstrated that the maximum adsorption capacity of LHA,Frl,Fr2,Fr3,Fr4,and Fr5 was 5.99,13.69,10.29,7.02,5.9&and 5.09 on kaolinite while it was 8.29,22.62,13.17,8.91,8.62,and 5.69 on montmorillonite,respectively.The adsorption equilibrium data showed that the adsorption behavior of LHA and its fractions could be described more practically by the Langmuir model than the Freundlich model.The rate of humic acid fraction adsorption onto clays increased with decreasing molecular size fraction and increasing carboxylic group content.Pseudo-first-and second-order models were used to assess the kinetic data and the rate constants.The results explained that LHA and its fractions adsorption on clay minerals conformed more to pseudosecondo rder.
文摘The present work aimed at the study of citric acid solvent extraction in order to establish the composition of the organic phase and to obtain thermodynamic and kinetic data for the chosen system. Discontinuous extraction experiments in a single stage were performed from a synthetic solution of citric acid, with the typical concentration (10% w/v) observed in industrial fermented musts. Exploratory experiments were carried out using different organic phases in order to select the most suitable solvent phase to further continuous extraction tests in a mechanically agitated column. The selected organic phase composition was: Alamine? 336, ExxalTM 13 tridecyl alcohol, and the aliphatic diluent EscaidTM 110. Next, the effects of the contact time and of the concentrations of extractant and modifier on the citric acid extraction were studied. Among the investigated conditions, the best one was 10 minutes of contact time, 30% w/v of Alamine? 336, and 10% w/v of ExxalTM 13 tridecyl alcohol. For this condition, the equilibrium isotherm (28°C ± 2°C) was determined, and the equilibrium constant was calculated (36.8 (mol·L-1)-1.5). It was considered that trioctylamine and citric acid complexation reaction occurs mainly with non-dissociated citric acid form, because the aqueous feed solutions’ pH is lower than the citric acid pKa1. It was found that 1.5 molecules of the extractant, on average, are required to react with one citric acid molecule, which can indicate that reactions with different extractant/citric acid ratios occur simultaneously. Next, the rate constants for the direct and inverse reactions, 2.10 (mol·L-1)-1.5·s-1 and 5.69 × 10-2 s-1, respectively, were calculated. Coefficients of determination (R2) values higher than 0.93 were found in these calculations, suggesting that the results obtained using a computer modeling would be very close to those results obtained experimentally. Therefore, the present work provides data required to future modelling, design, and simulation of citric acid solvent extraction processes.
文摘针对甲基丙烯酸(MAA)与水(H_(2)O)形成共沸混合物、MAA水溶液分离难的问题,开展了MAA水溶液提纯过程萃取剂筛选、MAA H_(2)O萃取剂三元液液相平衡数据测定与关联等研究。通过对甲苯、正己烷、环己烷、邻苯二甲酸二丁酯(DBP)4种萃取剂的萃取效率进行考察,确定DBP为综合性能最优的萃取剂。测定了常压条件下20、30、40℃时H_(2)O MAA DBP三元体系的液液相平衡数据,实验结果通过了Hand方程和Othmer Tobias方程对相平衡数据的一致性验证,线性相关性系数R^(2)值超0.99。使用UNIQUAC模型来拟合实验数据得到三组分二元交互作用参数,模型预测值与实验值的均方根偏差小于0.07,表明实验数据及拟合参数均有较高的准确性,为DBP应用于工业MAA水溶液提纯过程开发提供基础。
