McGill University, 3610 University Street, Montreal, QC H3A 2B2, Canada.
J Hazard Mater. 2011 Jan 15;185(1):148-54. doi: 10.1016/j.jhazmat.2010.09.009. Epub 2010 Sep 15.
In this study, the removal/precipitation of selenium with sodium sulfide from initially weakly acidic sulfate solutions containing 300 mg/L of selenium(IV) at 23 °C was studied. The results showed that, below a pH of approximately 7.0, the precipitation reaction was complete at a sulfide to selenium ratio above 1.8 and less than 11 with less than 0.005 mg/L of soluble selenium remaining in solution. When the pH rose between 7.0 and 9.5 the precipitation of selenium was incomplete. Above pH 9.5 the solution turned dark red but no precipitation was apparent. The precipitation reaction started as soon as the sodium sulfide was added in the selenium-bearing solution and was completed in less than 10 min. The orange "selenium sulfide" precipitates, characterized using X-ray diffraction, scanning electron microscopy and chemical analysis, were crystalline in the form of aggregated dense particles with their sulfur/selenium molar ratio varying from 1.7 to 2.3. The precipitate was deduced to be a Se-S solid solution consisting of ring molecules of the following Se(n)S(8-n) formula, where n = 2.5-3. Long term leachability tests (>2 month equilibration) under ambient conditions at pH 7 showed the produced precipitate to be essentially insoluble (<0.005 mg/L).
在这项研究中，研究了在 23°C 下从初始 pH 值约为 7.0、含硒(IV)300mg/L 的弱酸性硫酸盐溶液中用硫化钠去除/沉淀硒。结果表明，在 pH 值低于约 7.0 时，在硫化物与硒的比例大于 1.8 且小于 11 的条件下，沉淀反应完全，溶液中剩余的可溶性硒少于 0.005mg/L。当 pH 值在 7.0 到 9.5 之间上升时，硒的沉淀不完全。pH 值高于 9.5 时，溶液变成暗红色，但没有明显的沉淀。硫化钠一加入含硒溶液，沉淀反应就立即开始，不到 10 分钟就完成了。用 X 射线衍射、扫描电子显微镜和化学分析对橙色的“硒化硫”沉淀物进行了特征描述，其为具有硫/硒摩尔比从 1.7 到 2.3 的聚合致密颗粒形式的结晶。推断沉淀物是由以下 Se(n)S(8-n)公式组成的硒-硫固溶体，其中 n = 2.5-3。在环境条件下、pH 值为 7 时进行的长达 2 个月以上的长期浸出试验表明，所生成的沉淀物基本上是不溶的（<0.005mg/L）。
