The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkalinezincate solution were characterized by scanning electron microscope(SEM).The cathodic reaction m...The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkalinezincate solution were characterized by scanning electron microscope(SEM).The cathodic reaction mechanisms under variousconcentrations of additives were investigated using cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)techniques.It is found that with increasing the additive A content in the bath solution,the nucleation overpotential(NOP)value isobviously increased and the inhibition effect is strengthened.This may be mainly due to the adsorption of additive A on the cathodicelectrode surface,which can cover the active sites and block the discharge reduction.The results of EIS analysis indicate that therate-determining step of zinc electrodeposition process is changed from mixed control step into electrochemical reduction step in thepresence of additive A.However,any quantity of additive B has little effect on the NOP value and the inhibition effect is not obvious.Furthermore,addition of additive A and additive B at the same time displays the strongest inhibition effect and shows a strongsynergism because of their co-adsorption on the cathodic electrode surface.展开更多
Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The Tafel slopes of cathodic and anodic processes are -0.113 8 V and -0.041 18 V, the anodic and c...Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The Tafel slopes of cathodic and anodic processes are -0.113 8 V and -0.041 18 V, the anodic and cathodic apparent transfer coefficients are 0.519 3 and 1.435 2, respectively, and the stoichiometric number of rate-deterrnining step is 1. The theoretical kinetics equation of electrode reaction was deduced, from which the dynamic parameters can be calculated as follows： the cathodic and anodic Tafel slopes are -0.118 V and -0.039 4 V, respectively, consisting with the experimental values, Finally, the correctness of the mechanism was further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.展开更多
The stability of ionic liquid additive 1-butyl-3-methylimidazolium hydrogen sulfate （[BMIM]HSO4） during zinc electrowinning from acidic sulfate solution was investigated by cyclic voltammetry, electrochemical impeda...The stability of ionic liquid additive 1-butyl-3-methylimidazolium hydrogen sulfate （[BMIM]HSO4） during zinc electrowinning from acidic sulfate solution was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. Compared with the traditional industrial additives, gelatine and gum arabic, [BMIM]HSO4 has more excellent chemical and thermal stabilities. The inhibition effects of gelatine and gum arabic on the zinc electrocrystallization are observed to markedly weaken due to their part degradation after 12 h longtime successive electrolysis and high temperature （90 ℃） treatments. In contrast, the activity of [BMIM]HSO4 is practically unaffected after 24 h longtime successive electrolysis and high temperature treatments. These results are corroborated with the corresponding morphological analysis of the cathodic deposits.展开更多
The effects of surfactant on the solvent extraction in leachingsphalerite were investigated. It is found that sodium dodecylsulfonate is the effective surfactant in improving the zinc recoveryfrom sphalerite in the aq...The effects of surfactant on the solvent extraction in leachingsphalerite were investigated. It is found that sodium dodecylsulfonate is the effective surfactant in improving the zinc recoveryfrom sphalerite in the aqueous FeCl_3-HCl-tetrachloroethylene system.Through the measurements of surface tension and viscosity of thesphalerite Slurry modified with different surfactants, it isconcluded that sodium dodecyl sulfonate in the concentration rang Of0.05 to 0.2 g·L^-1 can improve the viscosity of sphalerite slurry inthe water, decrease the surface tension of Leaching solution, preventthe aggregation of ore particles, and give very high zinc extraction.展开更多
基金Project(2014CB643401)supported by the National Basic Research Program of ChinaProjects(51134007,51404299)supported by the National Natural Science Foundation of China
文摘The effects of additives on the surface and cross-sectional morphologies of zinc deposits on iron substrate from alkalinezincate solution were characterized by scanning electron microscope(SEM).The cathodic reaction mechanisms under variousconcentrations of additives were investigated using cyclic voltammetry(CV)and electrochemical impedance spectroscopy(EIS)techniques.It is found that with increasing the additive A content in the bath solution,the nucleation overpotential(NOP)value isobviously increased and the inhibition effect is strengthened.This may be mainly due to the adsorption of additive A on the cathodicelectrode surface,which can cover the active sites and block the discharge reduction.The results of EIS analysis indicate that therate-determining step of zinc electrodeposition process is changed from mixed control step into electrochemical reduction step in thepresence of additive A.However,any quantity of additive B has little effect on the NOP value and the inhibition effect is not obvious.Furthermore,addition of additive A and additive B at the same time displays the strongest inhibition effect and shows a strongsynergism because of their co-adsorption on the cathodic electrode surface.
文摘Kinetic parameters of the electrode reactions were measured by investigating steady-state current-potential behaviors. The Tafel slopes of cathodic and anodic processes are -0.113 8 V and -0.041 18 V, the anodic and cathodic apparent transfer coefficients are 0.519 3 and 1.435 2, respectively, and the stoichiometric number of rate-deterrnining step is 1. The theoretical kinetics equation of electrode reaction was deduced, from which the dynamic parameters can be calculated as follows： the cathodic and anodic Tafel slopes are -0.118 V and -0.039 4 V, respectively, consisting with the experimental values, Finally, the correctness of the mechanism was further demonstrated using apparent transfer coefficient according to the electrochemical dynamic equation of multi-electron reaction.
基金Project(2011FA009) supported by the Natural Science Foundation of Yunnan Province,ChinaProject(2011FZ020) supported by the Application Foundation Research of Yunnan Province,China
文摘The stability of ionic liquid additive 1-butyl-3-methylimidazolium hydrogen sulfate （[BMIM]HSO4） during zinc electrowinning from acidic sulfate solution was investigated by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. Compared with the traditional industrial additives, gelatine and gum arabic, [BMIM]HSO4 has more excellent chemical and thermal stabilities. The inhibition effects of gelatine and gum arabic on the zinc electrocrystallization are observed to markedly weaken due to their part degradation after 12 h longtime successive electrolysis and high temperature （90 ℃） treatments. In contrast, the activity of [BMIM]HSO4 is practically unaffected after 24 h longtime successive electrolysis and high temperature treatments. These results are corroborated with the corresponding morphological analysis of the cathodic deposits.
基金Supported by the National Natural Science Foundation of China (No. 29836130).
文摘The effects of surfactant on the solvent extraction in leachingsphalerite were investigated. It is found that sodium dodecylsulfonate is the effective surfactant in improving the zinc recoveryfrom sphalerite in the aqueous FeCl_3-HCl-tetrachloroethylene system.Through the measurements of surface tension and viscosity of thesphalerite Slurry modified with different surfactants, it isconcluded that sodium dodecyl sulfonate in the concentration rang Of0.05 to 0.2 g·L^-1 can improve the viscosity of sphalerite slurry inthe water, decrease the surface tension of Leaching solution, preventthe aggregation of ore particles, and give very high zinc extraction.
