为了提高臭葱石的稳定性,本文作者提出一种合成并原位包覆臭葱石的方法.在Fe(II)-As(V)-H2O体系、90℃和pH 1.5的条件下持续通入氧气合成多面体状和山梅状臭葱石颗粒.当初始Fe(II)/As(V)摩尔比超过1:1时,在合成过程中,一种含硫酸根的铁的氧化物或氢氧化物包覆层包覆在臭葱石颗粒表面.为了检测这些合成样品的浸出稳定性,用TCLP毒性浸出方法对样品在pH 4.93进行60 h的浸出实验.此外,用多种不同pH 5.40～10.88浸出溶液对样品进行30～40 d的浸出实验.浸出结果表明,该包覆层能有效延缓臭葱石中砷的释放;TCLP结果显示,其被包覆后砷的浸出浓度低至0.12 mg/L,长周期浸出实验显示砷的浸出浓度低于0.5 mg/L.%To improve stability of scorodite, a method of simultaneous synthesis and in-situ coating of scorodite was proposed. Scorodite particles with polyhedral and raspberry-like morphologies were synthesized in an Fe(II)-As(V)-H2O system at 90 ℃ and pH 1.5 by blowing oxygen gas into the system. When the initial Fe/As molar ratio exceeded 1:1, a coating of sulfate-containing iron (hydr)oxides formed on the surfaces of scorodite particles during synthesis. To evaluate the leaching stability of synthesized scorodite samples, toxicity characteristic leaching procedure (TCLP) tests were conducted at pH 4.93 for 60 h, and long-term leaching tests were conducted for 30-40 d within a pH range of 5.40-10.88. The leaching results indicated that the release of arsenic from scorodite was noticeably postponed by the coating, and the average arsenic concentrations in the leaching solutions were as low as 0.12 mg/L in the TCLP tests and lower than 0.5 mg/L in the long-term leaching tests.
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