The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous subs...The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.展开更多
The aim of this investigation was to prepare geopolymeric precursor from vanadium tailing(VT)by thermal activation and modification.For activation,a homogeneous blend of VT and sodium hydroxide was calcinated at an el...The aim of this investigation was to prepare geopolymeric precursor from vanadium tailing(VT)by thermal activation and modification.For activation,a homogeneous blend of VT and sodium hydroxide was calcinated at an elevated temperature and then modified with metakaolin to produce a geopolymeric precursor.During the thermal activation,the VT was corroded by sodium hydroxide and then sodium silicate formed on the particle surfaces.After water was added,the sodium silicate coating dissolved to release silicon species,which created an alkaline solution environment.The metakaolin then dissolved in the alkaline environment to generate aluminum species,which was followed by geopolymerization.The VT particles were connected by a gel produced during geopolymerization,which yielded a geopolymer with excellent mechanical performance.This investigation not only improves the feasibility of using geopolymer technology for large-scale and in-situ applications,but also promotes the utilization of VT and other silica-rich solid wastes.展开更多
Adhesion is an important process of particle-bubble interaction in fine particle(-10μm)flotation.This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a hig...Adhesion is an important process of particle-bubble interaction in fine particle(-10μm)flotation.This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera,atomic force microscope(AFM),adsorption capacity tests,and induction time tests.After being pretreated with nanobubbles(NBs)water,fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid(CHA)as a collector.The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage.The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration.The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals.Since NBs played a part of the role of collector,it can improve the flotation effect while reducing the amount of collector.The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles.On the other hand,NBs agglomerate cassiterite particles,increasing the probability of particles colliding with bubbles.展开更多
Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscop...Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software.The effects of the microwave power,leaching temperature,CaF_(2) dosage,H_(2)SO_(4) concentration,and leaching time on the vanadium recovery were investigated.A vanadium recovery of 80.66%is obtained at a microwave power of 550 W,leaching temperature of 95℃,CaF_(2) dosage of 5wt%,H_(2)SO_(4) concentration of 20vol%,and leaching time of 2.5 h.Compared with conventional leaching technology,the vanadium recovery increases by 6.18%,and the leaching time shortens by 79.17%.More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process.Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field(E-field).The distributions of E-field and temperature among vanadium shale particles are relatively uniform,except for the higher content at the contact position of the particles.The analysis results of scaleup experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching,and the local high temperature destroys the mineral structure and accelerates the reaction rate.展开更多
The effect and mechanism of ultrasound and CaF_(2) on vanadium leaching from vanadium-bearing shale were investigated systematically.In consideration of the enhancement for vanadium recovery,the combination of ultraso...The effect and mechanism of ultrasound and CaF_(2) on vanadium leaching from vanadium-bearing shale were investigated systematically.In consideration of the enhancement for vanadium recovery,the combination of ultrasound and CaF_(2)(66.28%) exerts more evident effects than ultrasound(26.97%) and CaF_(2)(60.35%) alone,demonstrating the synergetic effect of ultrasound and CaF_(2).Kinetic analysis manifests that the product layer diffusion controls vanadium leaching in ultrasound system without CaF_(2),however product layer diffusion and interfacial reaction is the rate-controlling step for vanadium leaching in other three leaching systems.The combination of ultrasound and CaF_(2) notably decreases the activation energy(E_(a)) from 62.03 to 27.61 kJ/mol,nevertheless individual CaF_(2) only reduces the E_(a) to 50.70 kj/mol.X-ray diffraction and fourier transform infrared spectrometer analyses show that the decomposition degree of the vanadium-bearing mica structure is the most significant in ultrasound and CaF_(2) system,proving the highest release degree of vanadium.Specific surface area and pore distribution combined with scanning electron microscope analyses reveal that the action of ultrasound and CaF_(2) would provide higher specific surface area,more abundant pores structure and cracks for the particles,which further prompts the rapid diffusion of H^(+),F^(-)and HF,and achieves the conspicuous improvement of vanadium leaching recovery.展开更多
The vanadium redox flow battery with a safe and capacity-controllable large-scale energy storage system offers a new method for the sustainability.In this case,acetic acid,methane sulfonic acid,sulfonic acid,amino met...The vanadium redox flow battery with a safe and capacity-controllable large-scale energy storage system offers a new method for the sustainability.In this case,acetic acid,methane sulfonic acid,sulfonic acid,amino methane sulfonic acid,and taurine are used to overcome the low electrolyte energy density and stability limitations,as well as to investigate the effects of various organic functional groups on the vanadium redox flow battery.When compared to the pristine electrolyte(0.22 Ah,5.0 Wh·L^(−1),85.0%),the results show that taurine has the advantage of maintaining vanadium ion concentrations,discharge capacity(1.43 Ah),energy density(33.9 Wh·L^(−1)),and energy efficiency(90.5%)even after several cycles.The acetic acid electrolyte is more conducive to the low-temperature stability of the V(II)electrolyte(177 h at−25℃)than pristine(82 h at−2℃).The−SO_(3)H group,specifically the coaction of the−NH_(2)and−SO_(3)H groups,improves electrolyte stability.The−NH_(2)and−COOH additive groups improved conductivity and electrochemical activity.展开更多
Ag-and Pt-doped WO3-0.33 H2O nanorods with high response and selectivity to NH3 were synthesized from a tungsten-containing mine ral of scheelite concentrate by a simple combined process,namely by a high pressure leac...Ag-and Pt-doped WO3-0.33 H2O nanorods with high response and selectivity to NH3 were synthesized from a tungsten-containing mine ral of scheelite concentrate by a simple combined process,namely by a high pressure leaching method to obtain tungstate ions-containing leaching solution and followed by a hydrothermal method to prepare corresponding nanorods.The microstructure and NH3 sensing perfo rmance of the final products were investigated systematically.The microstructure characte rization showed that the as-prepared WO3-0.33 H2 O nanorods had a hexagonal crystal structure,and Ag and Pt nanoparticles were uniformly distributed in the WO3-0.33 H2O nano rods.Gas sensing measurements indicated that Ag and Pt nanopa rticles not only could obviously enhance NH3 sensing properties in terms of response,selectivity as well as response/recovery time,but also could reduce the optimal operating temperature at which the highest response was achieved.The highest responses of 22.4 and 47.6 for Agand Pt-doped WO3-0.33 H2O nanorods to 1000 ppm NH3 were obtained at 225 and 175℃,respectively,which were about four and eight folds higher than that of pure one at 250℃.The superior NH3 sensing properties are mainly ascribed to the catalytic activities of noble metals and the different work functions between noble metals and WO3-0.33 H2 O.展开更多
High-manganese containing vanadium waste-water(HMVW)is commonly produced during the vanadium extraction process from vanadium titano-magnetite.HMVW cannot be reused and discharged directly,and is harmful to the enviro...High-manganese containing vanadium waste-water(HMVW)is commonly produced during the vanadium extraction process from vanadium titano-magnetite.HMVW cannot be reused and discharged directly,and is harmful to the environment and affect product quality due to heavy metals in the wastewater.The wastewater is usually treated by lime neutralization,but valuable metals(especially V and Mn)cannot be recovered.In this study,an efficient and environmentally friendly method was developed to recover valuable metals by using a solvent extraction-precipitation process.In the solvent extraction process,98.15%of vanadium was recovered,and the V2Os product,with a purity of 98.60%,was obtained under optimal conditions.For the precipitation process,91.05%of manganese was recovered as MnCO3 which meets the III grade standard of HG/T 2836-2011.Thermodynamic simulation analysis indicated that MnCO3 was selectively precipitated at pH 6.5 while Mg and Ca could hardly be precipitated.The results of X-ray diffraction and scanning electron microscopy demonstrated that the obtained V2Os and MnCO3 displayed a good degree of crystallinity.The treated wastewater can be returned for leaching,and resources(V and Mn)in the wastewater were utilized efficiently in an environmentally friendly way.Therefore,this study provides a novel method for the coextraction of V and Mn from HMVW.展开更多
Separation of vanadium from black shale leaching solution at low pH is very meaningful,which can effectively avoid the generation of alkali neutralization slag and the resulting vanadium loss.In this study,coordinatio...Separation of vanadium from black shale leaching solution at low pH is very meaningful,which can effectively avoid the generation of alkali neutralization slag and the resulting vanadium loss.In this study,coordination mechanism of vanadium in acid leaching solution at low pH was investigated with the intervention of chloride ions.Under the conditions of pH 0.8,di-(2-ethylhexyl)phosphoric acid concentration of 20%,phase ratio of 1:2,and extraction time of 8 min,the vanadium extraction could reach 80.00%.The Fourier transform infrared and electrospray ionization results reveal that,despite the fact that the chloride ion in the leachate could significantly promote vanadium extraction,the chloride ion does not enter the organic phase,indicating an intriguing phenomenon.Among Cl^(-)-V,SO_(4)^(2-)-V,and H_(2)O-V,the V-Cl bond is longer and the potential difference between coordinate ions and vanadium is smaller.Therefore,Vo^(2+)gets easily desorbed with chloride ions and enter the organic phase.At the same time,the hydrogen ions of di-(2-ethylhexyl)phosphoric acid also enter the water phase more easily,which reduces the pH required for the extraction reaction.展开更多
Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and ...Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and stable operation at high temperatures. Static stability tests have shown that VOPO4 precipitation occurs only with vanadium(V) electrolyte. The concentration of vanadium ion of 2.0–2.2 mol·L^(–1), phosphoric acid of 0.10–0.15 mol·L^(–1), and sulfuric acid of 2.5–3.0 mol·L^(–1) are suitable for a vanadium redox flow battery in the temperature range from –20 to 50 ℃. The equations for predicting the viscosity and conductivity of electrolytes are obtained by the response surface method. The optimized electrolyte overcomes precipitation generation. It has 2.8 times higher energy density than the non-phosphate electrolyte, and a coulomb efficiency of 94.0% at 50 ℃. The sulfate-phosphoric mixed acid system electrolyte promotes the electrode reaction process, increases the current density, and reduces the resistance. This work systematically optimizes the concentrations of composition of positive and negative vanadium electrolytes with mixed sulfate-phosphoric acid. It provides a basis for the different valence states and comprehensive properties of sulfate-phosphoric mixed acid system vanadium electrolytes under extreme environments, guiding engineering applications.展开更多
基金supported by Key R&D Program of Zhejiang Province,China (No.2022C03061)the National Natural Science Foundation of China (No.52074204)the Fundamental Research Funds for the Central Universities (No.2023-vb-032).
文摘The proper recycling of spent lithium-ion batteries(LIBs)can promote the recovery and utilization of valuable resources,while also negative environmental effects resulting from the presence of toxic and hazardous substances.In this study,a new environmentally friendly hydro-metallurgical process was proposed for leaching lithium(Li),nickel(Ni),cobalt(Co),and manganese(Mn)from spent LIBs using sulfuric acid with citric acid as a reductant.The effects of the concentration of sulfuric acid,the leaching temperature,the leaching time,the solid-liquid ratio,and the reducing agent dosage on the leaching behavior of the above elements were investigated.Key parameters were optimized using response surface methodology(RSM)to maximize the recovery of metals from spent LIBs.The maxim-um recovery efficiencies of Li,Ni,Co,and Mn can reach 99.08%,98.76%,98.33%,and 97.63%.under the optimized conditions(the sulfuric acid concentration was 1.16 mol/L,the citric acid dosage was 15wt%,the solid-liquid ratio was 40 g/L,and the temperature was 83℃ for 120 min),respectively.It was found that in the collaborative leaching process of sulfuric acid and citric acid,the citric acid initially provided strong reducing CO_(2)^(-),and the transition metal ions in the high state underwent a reduction reaction to produce transition metal ions in the low state.Additionally,citric acid can also act as a proton donor and chelate with lower-priced transition metal ions,thus speeding up the dissolution process.
基金This work was financially supported by the Major Tech-nical Innovation Project of Hubei Province,China(No.2018ACA157)the National Natural Science Foundation of China(No.51874222)the Excellent Dissertation Cul-tivation Funds of Wuhan University of Technology(No.2018-YS-052).
文摘The aim of this investigation was to prepare geopolymeric precursor from vanadium tailing(VT)by thermal activation and modification.For activation,a homogeneous blend of VT and sodium hydroxide was calcinated at an elevated temperature and then modified with metakaolin to produce a geopolymeric precursor.During the thermal activation,the VT was corroded by sodium hydroxide and then sodium silicate formed on the particle surfaces.After water was added,the sodium silicate coating dissolved to release silicon species,which created an alkaline solution environment.The metakaolin then dissolved in the alkaline environment to generate aluminum species,which was followed by geopolymerization.The VT particles were connected by a gel produced during geopolymerization,which yielded a geopolymer with excellent mechanical performance.This investigation not only improves the feasibility of using geopolymer technology for large-scale and in-situ applications,but also promotes the utilization of VT and other silica-rich solid wastes.
基金financially supported by the National Natural Science Foundation of China(Nos.U2003129 and 51504175)China Scholarship Council(No.201706955031)。
文摘Adhesion is an important process of particle-bubble interaction in fine particle(-10μm)flotation.This paper studied the adhesion process and mechanism between nanobubbles and fine cassiterite particles by using a high-speed camera,atomic force microscope(AFM),adsorption capacity tests,and induction time tests.After being pretreated with nanobubbles(NBs)water,fine cassiterite particles flotation tests were carried out using caprylhydroxamic acid(CHA)as a collector.The results showed that NBs can improve the recovery and flotation rate of fine cassiterite while decreasing the collector dosage.The adsorption capacity test indicated that the cassiterite treated with NBs had lower demand for collector concentration.The AFM imaging results further demonstrate that NBs could reduce the adsorption of CHA on the surface of minerals.Since NBs played a part of the role of collector,it can improve the flotation effect while reducing the amount of collector.The induction time test and the high-speed camera observation test showed that NBs promoted the attachment between bubbles and cassiterite particles.On the other hand,NBs agglomerate cassiterite particles,increasing the probability of particles colliding with bubbles.
基金supported by the National Natural Science Foundation of China(No.51904211)the National Natural Science Foundation of China(No.52004187)。
文摘Microwave heating can rapidly and uniformly raise the temperature and accelerate the reaction rate.In this paper,microwave heating was used to improve the acid leaching,and the mechanism was investigated via microscopic morphology analysis and numerical simulation by COMSOL Multiphysics software.The effects of the microwave power,leaching temperature,CaF_(2) dosage,H_(2)SO_(4) concentration,and leaching time on the vanadium recovery were investigated.A vanadium recovery of 80.66%is obtained at a microwave power of 550 W,leaching temperature of 95℃,CaF_(2) dosage of 5wt%,H_(2)SO_(4) concentration of 20vol%,and leaching time of 2.5 h.Compared with conventional leaching technology,the vanadium recovery increases by 6.18%,and the leaching time shortens by 79.17%.More obvious pulverization of shale particles and delamination of mica minerals happen in the microwave-assisted leaching process.Numerical simulation results show that the temperature of vanadium shales increases with an increase in electric field(E-field).The distributions of E-field and temperature among vanadium shale particles are relatively uniform,except for the higher content at the contact position of the particles.The analysis results of scaleup experiments and leaching experiments indicate high-temperature hot spots in the process of microwave-assisted leaching,and the local high temperature destroys the mineral structure and accelerates the reaction rate.
基金supported by the National Natural Science Foundation of China (51874222 and 52074204)the Fundamental Research Funds for the Central Universities (No. 2020-YB029)。
文摘The effect and mechanism of ultrasound and CaF_(2) on vanadium leaching from vanadium-bearing shale were investigated systematically.In consideration of the enhancement for vanadium recovery,the combination of ultrasound and CaF_(2)(66.28%) exerts more evident effects than ultrasound(26.97%) and CaF_(2)(60.35%) alone,demonstrating the synergetic effect of ultrasound and CaF_(2).Kinetic analysis manifests that the product layer diffusion controls vanadium leaching in ultrasound system without CaF_(2),however product layer diffusion and interfacial reaction is the rate-controlling step for vanadium leaching in other three leaching systems.The combination of ultrasound and CaF_(2) notably decreases the activation energy(E_(a)) from 62.03 to 27.61 kJ/mol,nevertheless individual CaF_(2) only reduces the E_(a) to 50.70 kj/mol.X-ray diffraction and fourier transform infrared spectrometer analyses show that the decomposition degree of the vanadium-bearing mica structure is the most significant in ultrasound and CaF_(2) system,proving the highest release degree of vanadium.Specific surface area and pore distribution combined with scanning electron microscope analyses reveal that the action of ultrasound and CaF_(2) would provide higher specific surface area,more abundant pores structure and cracks for the particles,which further prompts the rapid diffusion of H^(+),F^(-)and HF,and achieves the conspicuous improvement of vanadium leaching recovery.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51774216)Hubei Technical Innovation Special Project of China(Grant No.2017ACA185)Outstanding Young and Middle-aged Science and Technology Innovation Team Project of Hubei Province(Grant No.T201802).
文摘The vanadium redox flow battery with a safe and capacity-controllable large-scale energy storage system offers a new method for the sustainability.In this case,acetic acid,methane sulfonic acid,sulfonic acid,amino methane sulfonic acid,and taurine are used to overcome the low electrolyte energy density and stability limitations,as well as to investigate the effects of various organic functional groups on the vanadium redox flow battery.When compared to the pristine electrolyte(0.22 Ah,5.0 Wh·L^(−1),85.0%),the results show that taurine has the advantage of maintaining vanadium ion concentrations,discharge capacity(1.43 Ah),energy density(33.9 Wh·L^(−1)),and energy efficiency(90.5%)even after several cycles.The acetic acid electrolyte is more conducive to the low-temperature stability of the V(II)electrolyte(177 h at−25℃)than pristine(82 h at−2℃).The−SO_(3)H group,specifically the coaction of the−NH_(2)and−SO_(3)H groups,improves electrolyte stability.The−NH_(2)and−COOH additive groups improved conductivity and electrochemical activity.
基金supported by the National Natural Science Foundation of China(Nos.51674067,51422402)FundamentalResearch Funds for the Central Universities(Nos.N180102032,N180106002,N180408018,N170106005)+3 种基金Liaoning Revitalization Talents Program(No.XLYC1807160)Liaoning BaiQianWan Talents Program(No.201892127)Open Foundation of State Key Laborato ry of Mineral Processing(No.BGRIMM-KJSKL-2019-12)Open Foundation of State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control(No.HB201902)。
文摘Ag-and Pt-doped WO3-0.33 H2O nanorods with high response and selectivity to NH3 were synthesized from a tungsten-containing mine ral of scheelite concentrate by a simple combined process,namely by a high pressure leaching method to obtain tungstate ions-containing leaching solution and followed by a hydrothermal method to prepare corresponding nanorods.The microstructure and NH3 sensing perfo rmance of the final products were investigated systematically.The microstructure characte rization showed that the as-prepared WO3-0.33 H2 O nanorods had a hexagonal crystal structure,and Ag and Pt nanoparticles were uniformly distributed in the WO3-0.33 H2O nano rods.Gas sensing measurements indicated that Ag and Pt nanopa rticles not only could obviously enhance NH3 sensing properties in terms of response,selectivity as well as response/recovery time,but also could reduce the optimal operating temperature at which the highest response was achieved.The highest responses of 22.4 and 47.6 for Agand Pt-doped WO3-0.33 H2O nanorods to 1000 ppm NH3 were obtained at 225 and 175℃,respectively,which were about four and eight folds higher than that of pure one at 250℃.The superior NH3 sensing properties are mainly ascribed to the catalytic activities of noble metals and the different work functions between noble metals and WO3-0.33 H2 O.
基金Projects(51904097,51804103)supported by the National Natural Science Foundation of ChinaProject(2019GGJS056)supported by the Training Program for Young Backbone Teachers in Colleges and Universities of Henan Province,China+2 种基金Project(HB201905)supported by Open Foundation of State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,ChinaProject(202102310548)supported by Scientific and Technological Project of Henan Province,ChinaProject(21IRTSTHN006)supported by Program for Innovative Research Team in the University of Henan Province,China。
基金This study was financially supported by Project of National Natural Science Foundation of China(Grant Nos.51774215,51474162,and 51774216)Project of Hubei Province Science Foundation of China(No.2018CFA068).
文摘High-manganese containing vanadium waste-water(HMVW)is commonly produced during the vanadium extraction process from vanadium titano-magnetite.HMVW cannot be reused and discharged directly,and is harmful to the environment and affect product quality due to heavy metals in the wastewater.The wastewater is usually treated by lime neutralization,but valuable metals(especially V and Mn)cannot be recovered.In this study,an efficient and environmentally friendly method was developed to recover valuable metals by using a solvent extraction-precipitation process.In the solvent extraction process,98.15%of vanadium was recovered,and the V2Os product,with a purity of 98.60%,was obtained under optimal conditions.For the precipitation process,91.05%of manganese was recovered as MnCO3 which meets the III grade standard of HG/T 2836-2011.Thermodynamic simulation analysis indicated that MnCO3 was selectively precipitated at pH 6.5 while Mg and Ca could hardly be precipitated.The results of X-ray diffraction and scanning electron microscopy demonstrated that the obtained V2Os and MnCO3 displayed a good degree of crystallinity.The treated wastewater can be returned for leaching,and resources(V and Mn)in the wastewater were utilized efficiently in an environmentally friendly way.Therefore,this study provides a novel method for the coextraction of V and Mn from HMVW.
基金supported by the National Key R&D Program of China(Grant No.2020YFC1909700)the Project of National Natural Science Foundation of China(Grant Nos.51974207 and 51774215).
文摘Separation of vanadium from black shale leaching solution at low pH is very meaningful,which can effectively avoid the generation of alkali neutralization slag and the resulting vanadium loss.In this study,coordination mechanism of vanadium in acid leaching solution at low pH was investigated with the intervention of chloride ions.Under the conditions of pH 0.8,di-(2-ethylhexyl)phosphoric acid concentration of 20%,phase ratio of 1:2,and extraction time of 8 min,the vanadium extraction could reach 80.00%.The Fourier transform infrared and electrospray ionization results reveal that,despite the fact that the chloride ion in the leachate could significantly promote vanadium extraction,the chloride ion does not enter the organic phase,indicating an intriguing phenomenon.Among Cl^(-)-V,SO_(4)^(2-)-V,and H_(2)O-V,the V-Cl bond is longer and the potential difference between coordinate ions and vanadium is smaller.Therefore,Vo^(2+)gets easily desorbed with chloride ions and enter the organic phase.At the same time,the hydrogen ions of di-(2-ethylhexyl)phosphoric acid also enter the water phase more easily,which reduces the pH required for the extraction reaction.
基金supported by the National Natural Science Foundation of China(Grant No.51774216)Hubei Technical Innovation Special Project of China(Grant No.2017ACA185)Science and technology innovation Talent program of Hubei Province(Grant No.2022EJD002).
文摘Herein, the influence of the concentration design and comprehensive performance of the sulfate-phosphoric mixed acid system electrolyte is investigated to realize an electrolyte that maintains high energy density and stable operation at high temperatures. Static stability tests have shown that VOPO4 precipitation occurs only with vanadium(V) electrolyte. The concentration of vanadium ion of 2.0–2.2 mol·L^(–1), phosphoric acid of 0.10–0.15 mol·L^(–1), and sulfuric acid of 2.5–3.0 mol·L^(–1) are suitable for a vanadium redox flow battery in the temperature range from –20 to 50 ℃. The equations for predicting the viscosity and conductivity of electrolytes are obtained by the response surface method. The optimized electrolyte overcomes precipitation generation. It has 2.8 times higher energy density than the non-phosphate electrolyte, and a coulomb efficiency of 94.0% at 50 ℃. The sulfate-phosphoric mixed acid system electrolyte promotes the electrode reaction process, increases the current density, and reduces the resistance. This work systematically optimizes the concentrations of composition of positive and negative vanadium electrolytes with mixed sulfate-phosphoric acid. It provides a basis for the different valence states and comprehensive properties of sulfate-phosphoric mixed acid system vanadium electrolytes under extreme environments, guiding engineering applications.
