(浙江工業(yè)大學(xué) 化學(xué)工程與材料學(xué)院，杭州 310032)
摘 要: 通過霍爾槽試驗(yàn)研究氨絡(luò)合物體系中雜質(zhì)Zn2+對鎳電沉積的影響，采用電化學(xué)工作站測試不同Zn2+濃度時(shí)的循環(huán)伏安曲線、穩(wěn)態(tài)極化曲線及電流時(shí)間暫態(tài)曲線。結(jié)果表明：雜質(zhì)Zn2+的含量為0.1 g/L時(shí)，在小于2.78 A/dm的電流密度范圍內(nèi)可正常沉積出金屬鎳；雜質(zhì)Zn2+含量大于0.5 g/L時(shí)，在較大的電流密度范圍內(nèi)均無法正常沉積出金屬鎳；過電位小于640 mV時(shí)，Zn2+的存在不影響陰極反應(yīng)的傳遞系數(shù)，且不改變陰極反應(yīng)機(jī)理；當(dāng)過電位大于640 mV，且雜質(zhì)Zn2+的濃度大于0.5 g/L時(shí)，陰極反應(yīng)的傳遞系數(shù)減小，陰極反應(yīng)機(jī)理發(fā)生改變；雜質(zhì)Zn2+濃度大于0.5 g/L時(shí)，嚴(yán)重影響鎳電結(jié)晶過程的成核速率，這是其抑制金屬鎳電沉積的主要原因。因此，采用鎳氨絡(luò)合物體系電積金屬鎳，應(yīng)控制雜質(zhì)Zn2+的含量小于0.1 g/L。
關(guān)鍵字: 鎳；鋅；氨絡(luò)合物；陰極過程；電結(jié)晶
（College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032, China）
Abstract:In nickel ammonia system, the influence of impurity Zn2+ on the nickel electrodeposition was studied intensively by Hull Cell experiments, and the cyclic voltammetry, cathodic polarization and chronoamperometric curves were tested at different Zn2+ concentration by electrochemistry working station. The results show that nickel can be deposited normally when the concentration of impurity Zn2+ is 0.1 g/L and the cathodic current density is less than 2.78 A/dm. When the concentration of impurity Zn2+ is greater than 0.5 g/L, nickel can’t be deposited normally in a wide range of current density. The cathodic transfer coefficient α and reaction mechanism will not change with the addition of impurity Zn2+ when the overpotential is less than 640 mV. The cathodic transfer coefficient α decreases and the reaction mechanism changes when the overpotential is greater than 640 mV and the concentration of impurity Zn2+ is greater than 0.5 g/L. The nucleation rate during nickel electrocrystallization is restrained greatly when the impurity Zn2+ concentration is greater than 0.5 g/L, which is the main reason that inhibits the nickel electrodeposition. So, during electrowinning nickel from ammonia system, the content of purity Zn2+ should be controlled less than 0.1 g/L.
Key words: nickel; zinc; ammonia complex; cathodic process; electrocrystallization
