(中南大學(xué) 冶金科學(xué)與工程學(xué)院, 長沙 410083)
摘 要: 采用雙氧水和濃鹽酸與金粉反應(yīng)制得氯金酸， 并研究氯金酸的熱分解。 在5 g金粉中加入5倍理論量的雙氧水和2.49倍理論量的濃鹽酸， 當(dāng)反應(yīng)溫度為100 ℃時， 攪拌反應(yīng)20 min， 金粉完全溶解。 然后， 經(jīng)100 ℃濃縮、 濃H2SO4干燥制得橘黃色氯金酸晶體。 X射線衍射分析表明其化學(xué)式為HAuCl4·4H2O， 其質(zhì)量達到國家分析純試劑標準。 氯金酸的質(zhì)量損失和差熱(TG-DTA)分析結(jié)果表明： 在13.0~130.7 ℃、 130.7~186.8 ℃、 186.8~247.3 ℃、 247.3~344.5 ℃區(qū)間， 均發(fā)生了質(zhì)量損失反應(yīng)和吸熱變化， 其對應(yīng)的熱分解固體產(chǎn)物分別為HAuCl4、 AuCl3、 AuCl、 Au。 與王水法和飽和氯氣鹽酸法比較， 雙氧水鹽酸法溶金制備氯金酸具有安全性好、 污染小、 易操作等優(yōu)點。
關(guān)鍵字: 氯金酸； 雙氧水； 鹽酸； 金； 熱分解
（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
