无氰金盐亚硫酸金钠中氯离子的脱除研究

Study on removal of chlorine ions from cyanide-free gold salt sodium gold sulfite

亚硫酸金钠是无氰电镀金主要使用的金盐,但有关亚硫酸金钠中氯离子的脱除与含量控制还未有报道。试验制备了亚硫酸金钠溶液,并开展了氢氧化金中氯离子吸附行为和脱除研究。利用去离子水充分洗涤氢氧化金沉淀至滤液中滴加硝酸银无白色沉淀,制得的50 g/L(按Au计)亚硫酸金钠溶液中氯离子质量浓度在220 mg/L左右。通过吸附等温曲线拟合,氢氧化金对氯离子的吸附更加符合Langmuir吸附模型,吸附反应吉布斯自由能ΔG为-18.4 kJ/mol,氯离子吸附主要为物理吸附。采用乙醇反溶剂沉淀可以进一步脱除亚硫酸金钠中的氯离子,单次反溶剂沉淀氯离子脱除率约为43%,经3次反溶剂沉淀后可以使50 g/L(按Au计)亚硫酸金钠溶液中氯离子质量浓度降低至40 mg/L。研究结果可以为提高无氰金盐亚硫酸金钠产品质量提供一定的理论和技术指导。

Sodium gold sulfite is a major gold salt used in cyanide-free gold electroplating,but there is no report on the removal and control of chlorine ions in sodium gold sulfite.Sodium gold sulfite solution was prepared in tests,and the adsorption behavior and removal of chlorine ions in gold hydroxide were studied.The gold hydroxide was fully washed with deionized water until no white precipitate was observed when silver nitrate was added to the filtrate.The mass concentration of chlorine ions in the 50 g/L(calculated according to Au)sodium gold sulfite solution prepared was about 220 mg/L.Through the adsorption isotherm curve fitting,the adsorption of chlorine ions by gold hydroxide was fitter into the Langmuir adsorption model.The Gibbs free energy of the adsorption reaction was-18.4 kJ/mol,indicating that the adsorption of chlorine ions was mainly physical adsorption.The chlorine ions in sodium gold sulfite could be further removed by ethanol antisolvent precipitation.The removal rate of chlorine ions by single antisolvent precipitation was about 43%.After 3 times of antisolvent precipitation,the mass concentration of chlorine ions in the 50 g/L(calculated according to Au)sodium gold sulfite solution was reduced to 40 mg/L.The results of this paper could provide certain theoretical and technical guidance for improving the quality of sodium gold sulfite product,a cyanide-free gold salt.