Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The...Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The hydrogen evolution reaction and iron passivation process on these iron electrodes were investigated in alkaline and neutral solutions.The iron electrode Bi_(2)S_(3)-3@Fe-Gr(The additional amount of Bi_(2)S_(3)was 3 mg)revealed the strongest ability to inhibit hydrogen evolution among the iron electrodes of the present investigation,while the Bi_(2)S_(3)-6@Fe-Gr electrode(The additional amount of Bi_(2)S_(3)was 6 mg)delivered significant performance in inhibiting anodic passivation.This is because the high-energy ball milling process leads to the well-dispersion of Bi_(2)S_(3)and the changes in the surface of Fe nanoparticles,thereby slowing down the passivation of the iron electrode surface.展开更多
Effects of nickel component,thiourea,glue and chloride ions and their interactions on the passivation of copper–nickel based alloy scrap anodes were investigated by combining conventional electrochemical techniques.R...Effects of nickel component,thiourea,glue and chloride ions and their interactions on the passivation of copper–nickel based alloy scrap anodes were investigated by combining conventional electrochemical techniques.Results obtained from chronopotentiometry and linear voltammetry curves showed that the Ni component made electrochemical stability of the anode strong and difficult to be corroded,caused by the adsorption of generated Cu2O,NiO or copper powder to the anode surface.The Ni2+reducing Cu2+to Cu+or copper powder aggravated the anode passivation.In a certain range of the glue concentration≤8×10–6 or thiourea concentration≤4×10–6,the increase of glue or thiourea concentration increases the anode passivation time.Over this range,glue and thiourea played an adverse effect.The increase of chloride ions concentration led to the increase in passivation time.展开更多
The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated.Acidithiobacillus ferrooxidans affect...The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated.Acidithiobacillus ferrooxidans affects the dissolution of vanadium through the catalytic effect on Fe^3+/Fe^2+couple and material exchange.The passivation of iron settling correlates with ferrous ion content in bio-leaching solution.In medium containing A.ferrooxidans and Fe(Ⅲ),the increment in Fe(Ⅱ)concentration leads to the formation of jarosite,generating a decline in vanadium extraction efficiency.Analysis of cyclic voltammetry shows that Fe(Ⅱ)ion is apt to be oxidized and translated into precipitate by A.ferrooxidans,which strongly adsorbed to the surface of the residue.Fe(Ⅲ)ion promotes the vanadium extraction due to its oxidizing activity.Admixing A.ferrooxidans to Fe(Ⅲ)medium elevates the reduction of low valence state vanadium and facilitates the exchange of substance between minerals and solution.This motivates 3.8%and 21.8%increments in recovery ratio and leaching rate of vanadium compared to the Fe(Ⅲ)exclusive use,respectively.Moreover,Fe(Ⅱ)ion impacts vanadium extraction slightly in sterile medium but negatively influences vanadium leaching in the presence of bacteria.展开更多
An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process...An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that Pb F2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is β-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.展开更多
Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrr...Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrrhotite oxidation behavior is the preferential dissolution of iron accompanied with the massive formation of sulfur in the presence of L. ferriphilum, which significantly hinders the leaching efficiency. Comparatively, the leaching rate of pyrrhotite distinctly increases by 68% in the mixed culture of L. ferriphilum and A. caldus at the 3rd day. But, the accumulated ferric ions and high p H value produced by bioleaching process can give rise to the rapid formation of jarosite, which is the primary passivation film blocking continuous iron extraction during bioleaching by the mixed culture. The addition of A. caldus during leaching by L. ferriphilum can accelerate the oxidation rate of pyrrhotite, but not change the electrochemical oxidation mechanisms of pyrrhotite. XRD and SEM/EDS analyses as well as electrochemical study confirm the above conclusions.展开更多
The effects of cations stress of magnesium ion and sodium ion on the low-grade nickel sulfide ore oxidative leaching in simulated sulfuric acid solutions were investigated.This study was performed in two courses,inclu...The effects of cations stress of magnesium ion and sodium ion on the low-grade nickel sulfide ore oxidative leaching in simulated sulfuric acid solutions were investigated.This study was performed in two courses,including the effect of the cations on the valuable metals leaching efficiencies of the nickel ore and its influences on the electrochemical oxidation behavior of the nickel ore.The leaching results present that parts of magnesium-containing gangues and ferrous sulfide are preferentially dissolved into lixivium,and the leaching efficiencies of Ni and Cu decreased much related to the leached concentrations of Mg^2+increased.The results of electrochemical measurements show that the oxidation leaching of the low-grade nickel sulfide ore is controlled by the intermediates oxidative diffusion.Mg^2+,as well as Na^+,affects the transformations of the Fe^3+/Fe^2+ couple and sulfur-containing species,and those cations are apt to be attracted by the anions and directionally adhere to the negative active site of the metal sulfide surface,causing an increase in the electrochemical activities,which facilitates the electron transfer between the ore and leaching mediums.By comparative study of the role of Mg^2+ and Na^+,it is found that Mg^2+ negatively affects the oxidative diffusion of the intermediates through promoting the generation of a compact film,which lowers the metals leached efficiencies,and the unfavorable effect of Na+tends to be the coupled effect of the leached Mg^2+ and Fe^3+.展开更多
Deep level donor＇s ionization behavior of passive film formed on the surface of stainless steel was investigated by Mott-Schottky plots. It is indicated that transformation process of deep level donors＇ ionization b...Deep level donor＇s ionization behavior of passive film formed on the surface of stainless steel was investigated by Mott-Schottky plots. It is indicated that transformation process of deep level donors＇ ionization behavior of passive film on surface of stainless steel can be divided into 4 stages with rising immersion time. At the initial immersion stage （10 min）, Fe（II） located in the octahedral sites of the unit cell is not ionized and the deep level does not appear in Mott-Schottky plots. At the second stage （9-38 h）, Fe（II） located in the octahedral sites starts to be ionized, which results in deep level donors＇ generation and density of deep level donors almost is constant with augmenting immersion time but the thickness of space charge layer is more and more thicker with rising immersion time. At the third stage （48 h-12 d）, density of deep level donors rises with increasing immersion time and the thickness of passive films space charge layer decreases. At last stage （above 23 d）, both the space charge layer＇s thickness and density of deep level donors are no longer changed with increasing immersion time. In the overall immersion stage, the shallow level donors＇ density is invariable all the time. The mechanism of deep level donor＇s ionization can be the generation of metal vacancies, which results in crystal lattice＇s aberration and the aberration energy urges the ionization of Fe（ II ） in octahedral sites.展开更多
文摘Iron(Fe)nanoparticles and graphite(Gr)with different masses of bismuth trisulfide(Bi_(2)S_(3))were mixed by high-energy ball milling treatment to fabricate the corresponding composite iron anodes Bi_(2)S_(3)@Fe-Gr.The hydrogen evolution reaction and iron passivation process on these iron electrodes were investigated in alkaline and neutral solutions.The iron electrode Bi_(2)S_(3)-3@Fe-Gr(The additional amount of Bi_(2)S_(3)was 3 mg)revealed the strongest ability to inhibit hydrogen evolution among the iron electrodes of the present investigation,while the Bi_(2)S_(3)-6@Fe-Gr electrode(The additional amount of Bi_(2)S_(3)was 6 mg)delivered significant performance in inhibiting anodic passivation.This is because the high-energy ball milling process leads to the well-dispersion of Bi_(2)S_(3)and the changes in the surface of Fe nanoparticles,thereby slowing down the passivation of the iron electrode surface.
基金Project(51574135)supported by the National Natural Science Foundation of ChinaProject(KKPT201563022)supported by the Collaborative Innovation Center of Kunming University of Science and Technology,China
文摘Effects of nickel component,thiourea,glue and chloride ions and their interactions on the passivation of copper–nickel based alloy scrap anodes were investigated by combining conventional electrochemical techniques.Results obtained from chronopotentiometry and linear voltammetry curves showed that the Ni component made electrochemical stability of the anode strong and difficult to be corroded,caused by the adsorption of generated Cu2O,NiO or copper powder to the anode surface.The Ni2+reducing Cu2+to Cu+or copper powder aggravated the anode passivation.In a certain range of the glue concentration≤8×10–6 or thiourea concentration≤4×10–6,the increase of glue or thiourea concentration increases the anode passivation time.Over this range,glue and thiourea played an adverse effect.The increase of chloride ions concentration led to the increase in passivation time.
基金Project(DY135-B2-15) supported by the China Ocean Mineral Resource R&D AssociationProject(2015ZX07205-003) supported by Major Science and Technology Program for Water Pollution Control and Treatment,ChinaProjects(21176242,21176026) supported by the National Natural Science Foundation of China
文摘The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated.Acidithiobacillus ferrooxidans affects the dissolution of vanadium through the catalytic effect on Fe^3+/Fe^2+couple and material exchange.The passivation of iron settling correlates with ferrous ion content in bio-leaching solution.In medium containing A.ferrooxidans and Fe(Ⅲ),the increment in Fe(Ⅱ)concentration leads to the formation of jarosite,generating a decline in vanadium extraction efficiency.Analysis of cyclic voltammetry shows that Fe(Ⅱ)ion is apt to be oxidized and translated into precipitate by A.ferrooxidans,which strongly adsorbed to the surface of the residue.Fe(Ⅲ)ion promotes the vanadium extraction due to its oxidizing activity.Admixing A.ferrooxidans to Fe(Ⅲ)medium elevates the reduction of low valence state vanadium and facilitates the exchange of substance between minerals and solution.This motivates 3.8%and 21.8%increments in recovery ratio and leaching rate of vanadium compared to the Fe(Ⅲ)exclusive use,respectively.Moreover,Fe(Ⅱ)ion impacts vanadium extraction slightly in sterile medium but negatively influences vanadium leaching in the presence of bacteria.
基金Projects(51204208,51374240)supported by the National Natural Science Foundation of ChinaProject(2014zzts028)supported by the Fundamental Research Funds for the Central Universities of Central South University,China
文摘An attempt was made to build up a thick and compact oxide layer rapidly by pre-treating the Pb-Ag-Nd anode in fluoride-containing H2SO4 solution. The passivation reaction of Pb-Ag-Nd anode during pre-treatment process was investigated using cyclic voltammetry, linear scanning voltammetry, environmental scanning electron microscopy and X-ray diffraction analysis. The results show that Pb F2 and PbSO4 are formed near the potential of Pb/PbSO4 couple. The pre-treatment in fluoride-containing H2SO4 solution contributes to the formation of a thick, compact and adherent passive film. Furthermore, pre-treatment in fluoride-containing H2SO4 solution also facilitates the formation of PbO2 on the anodic layer, and the reason could be attributed to the formation of more PbF2 and PbSO4 during the pre-treatment which tend to transform to PbO2 during the following electrowinning process. In addition, the anodic layer on anode with pre-treatment in fluoride-containing H2SO4 solution is thick and compact, and its predominant composition is β-PbO2. In summary, the pre-treatment in fluoride-containing H2SO4 solution benefits the formation of a desirable protective layer in a short time.
基金Project(2010CB630903) supported by the National Basic Research Program of ChinaProject(51374249) supported by the National Natural Science Foundation of China
文摘Bioleaching and electrochemical experiments were conducted to evaluate pyrrhotite dissolution in the presence of pure L.ferriphilum and mixed culture of L. ferriphilum and A. caldus. The results indicate that the pyrrhotite oxidation behavior is the preferential dissolution of iron accompanied with the massive formation of sulfur in the presence of L. ferriphilum, which significantly hinders the leaching efficiency. Comparatively, the leaching rate of pyrrhotite distinctly increases by 68% in the mixed culture of L. ferriphilum and A. caldus at the 3rd day. But, the accumulated ferric ions and high p H value produced by bioleaching process can give rise to the rapid formation of jarosite, which is the primary passivation film blocking continuous iron extraction during bioleaching by the mixed culture. The addition of A. caldus during leaching by L. ferriphilum can accelerate the oxidation rate of pyrrhotite, but not change the electrochemical oxidation mechanisms of pyrrhotite. XRD and SEM/EDS analyses as well as electrochemical study confirm the above conclusions.
基金Projects(2019M650972,2017M621034)supported by China Postdoctoral Science Foundation。
文摘The effects of cations stress of magnesium ion and sodium ion on the low-grade nickel sulfide ore oxidative leaching in simulated sulfuric acid solutions were investigated.This study was performed in two courses,including the effect of the cations on the valuable metals leaching efficiencies of the nickel ore and its influences on the electrochemical oxidation behavior of the nickel ore.The leaching results present that parts of magnesium-containing gangues and ferrous sulfide are preferentially dissolved into lixivium,and the leaching efficiencies of Ni and Cu decreased much related to the leached concentrations of Mg^2+increased.The results of electrochemical measurements show that the oxidation leaching of the low-grade nickel sulfide ore is controlled by the intermediates oxidative diffusion.Mg^2+,as well as Na^+,affects the transformations of the Fe^3+/Fe^2+ couple and sulfur-containing species,and those cations are apt to be attracted by the anions and directionally adhere to the negative active site of the metal sulfide surface,causing an increase in the electrochemical activities,which facilitates the electron transfer between the ore and leaching mediums.By comparative study of the role of Mg^2+ and Na^+,it is found that Mg^2+ negatively affects the oxidative diffusion of the intermediates through promoting the generation of a compact film,which lowers the metals leached efficiencies,and the unfavorable effect of Na+tends to be the coupled effect of the leached Mg^2+ and Fe^3+.
基金Foundation item: Projects(50571059, 50615024 ) supported by the National Natural Science Foundation of ChinaProject(NCET-07-0536) supported by Program for New Century Excellent Talents in UniversityProject(IRT0739) supported by Program for Innovative Research Team in University
文摘Deep level donor＇s ionization behavior of passive film formed on the surface of stainless steel was investigated by Mott-Schottky plots. It is indicated that transformation process of deep level donors＇ ionization behavior of passive film on surface of stainless steel can be divided into 4 stages with rising immersion time. At the initial immersion stage （10 min）, Fe（II） located in the octahedral sites of the unit cell is not ionized and the deep level does not appear in Mott-Schottky plots. At the second stage （9-38 h）, Fe（II） located in the octahedral sites starts to be ionized, which results in deep level donors＇ generation and density of deep level donors almost is constant with augmenting immersion time but the thickness of space charge layer is more and more thicker with rising immersion time. At the third stage （48 h-12 d）, density of deep level donors rises with increasing immersion time and the thickness of passive films space charge layer decreases. At last stage （above 23 d）, both the space charge layer＇s thickness and density of deep level donors are no longer changed with increasing immersion time. In the overall immersion stage, the shallow level donors＇ density is invariable all the time. The mechanism of deep level donor＇s ionization can be the generation of metal vacancies, which results in crystal lattice＇s aberration and the aberration energy urges the ionization of Fe（ II ） in octahedral sites.
