(中南大学 冶金科学与工程学院, 长沙 410083)
摘 要: 采用双氧水和浓盐酸与金粉反应制得氯金酸， 并研究氯金酸的热分解。 在5 g金粉中加入5倍理论量的双氧水和2.49倍理论量的浓盐酸， 当反应温度为100 ℃时， 搅拌反应20 min， 金粉完全溶解。 然后， 经100 ℃浓缩、 浓H2SO4干燥制得橘黄色氯金酸晶体。 X射线衍射分析表明其化学式为HAuCl4·4H2O， 其质量达到国家分析纯试剂标准。 氯金酸的质量损失和差热(TG-DTA)分析结果表明： 在13.0~130.7 ℃、 130.7~186.8 ℃、 186.8~247.3 ℃、 247.3~344.5 ℃区间， 均发生了质量损失反应和吸热变化， 其对应的热分解固体产物分别为HAuCl4、 AuCl3、 AuCl、 Au。 与王水法和饱和氯气盐酸法比较， 双氧水盐酸法溶金制备氯金酸具有安全性好、 污染小、 易操作等优点。
关键字: 氯金酸； 双氧水； 盐酸； 金； 热分解
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract: Chloroauric acid was prepared by the method of hydrogen peroxide and hydrochloric acid. The thermal decomposition of chloroauric acid was researched. When the dosages of hydrogen peroxide and hydrochloric acid are respectively 5 and 2.49 times of theoretical dosage, the reaction temperature is 100 ℃, the dissolution of gold is 100% after gold is added into the solution of H2O2 and HCl and the reaction time is 20 min under the agitation. The orange crystal of chloroautic acid is obtained after chloroautic acid solution is evaporated at 100 ℃ and dried by concentrated sulfuric acid. X-ray diffraction analysis testifies that the chloroauric acid crystal is HAuCl4·4H2O. The quality of the chloroauric acid is up to the analytic reagent standard of China. TG-DTA analysis indicate that the mass loss and heat absorption occur respectively between 13.0-130.7 ℃, 130.7-186.8 ℃, 186.8 - 247.3 ℃, 247.3-344.5 ℃ in the process of heat treatment of chloroautic acid. The solid products of the decomposition are HAuCl4, AuCl3, AuCl, Au respectively. This method of dissolving gold to prepare chloroauric acid has such advantages as better security, less pollution, and easier operation in comparison with aqua regia method and chlorine-hydrochloric acid method.
Key words: chloroauric acid; hydrogen peroxide; hydrochloric acid; gold; thermal decomposition
