Behavior of Aluminum, Arsenic, and Vanadium during the Neutralization of Red Mud Leachate by HCl, Gypsum, or Seawater
Behavior of Aluminum, Arsenic, and Vanadium during the Neutralization of Red Mud Leachate by HCl, Gypsum, or Seawater
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DOI：
10.1021/es4010834
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发表时间：
2013-06-18
影响因子：
11.4
通讯作者：
Mayes, William M.
中科院分区：
文献类型：
--
作者：
Burke, Ian T.;Peacock, Caroline L.;Mayes, William M.
从匈牙利艾季卡收集的赤泥渗滤液(PH 13)用盐酸、石膏或海水中和至pH 10。在酸中和过程中，99%的铝在形成无定形薄水铝石状沉淀物和片钠铝石的过程中从溶液中除去。微量的砷(24%)也通过在氢氧化铝上的表面吸附从溶液中去除。在实验和从2010年10月赤泥泄漏后用石膏处理的河流中回收的现场样品中，向赤泥渗滤液中添加石膏都会导致方解石的沉淀。方解石的沉淀使溶液中的铝和砷的脱除率分别达到86%和81%，两者都不能与0.1mol L-1磷酸盐溶液交换。与新形成的氢氧化铝相反，EXAFS分析方解石沉淀物只显示孤立的砷四面体，没有表面吸附或并入方解石结构的证据，可能是方解石沉淀物非常迅速地清除的结果。海水中和也导致碳酸盐析出，溶液中99%的铝在形成无序的水滑石相过程中被去除，74%的铝通过表面吸附被新生成的沉淀物去除。一半的结合As可以被磷酸盐的加入重新活化，表明As是弱结合的，可能是在水滑石夹层中。在中和过程中，只有5-16%的V从溶液中去除，表明没有与任何新生成的沉淀物相互作用。因此，在赤泥渗滤液的处理过程中，高V浓度可能是一个棘手的问题。
Red mud leachate (pH 13) collected from Ajka, Hungary is neutralized to < pH 10 by HCl, gypsum, or seawater addition. During acid neutralization >99% Al is removed from solution during the formation of an amorphous boehmite-like precipitate and dawsonite. Minor amounts of As (24%) are also removed from solution via surface adsorption of As onto the Al oxyhydroxides. Gypsum addition to red mud leachate results in the precipitation of calcite, both in experiments and in field samples recovered from rivers treated with gypsum after the October 2010 red mud spill. Calcite precipitation results in 86% Al and 81% As removal from solution, and both are nonexchangeable with 0.1 mol L-1 phosphate solution. Contrary to As associated with neoformed Al oxyhydroxides, EXAFS analysis of the calcite precipitates revealed only isolated arsenate tetrahedra with no evidence for surface adsorption or incorporation into the calcite structure, possibly as a result of very rapid As scavenging by the calcite precipitate. Seawater neutralization also resulted in carbonate precipitation, with >99% Al and 74% As removed from solution during the formation of a poorly ordered hydrotalcite phase and via surface adsorption to the neoformed precipitates, respectively. Half the bound As could be remobilized by phosphate addition, indicating that As was weakly bound, possibly in the hydrotalcite interlayer. Only 5-16% V was removed from solution during neutralization, demonstrating a lack of interaction with any of the neoformed precipitates. High V concentrations are therefore likely to be an intractable problem during the treatment of red mud leachates.