Effects of pH, dissolved oxygen, and aqueous ferrous iron on the adsorption of arsenic to lepidocrocite.
Effects of pH, dissolved oxygen, and aqueous ferrous iron on the adsorption of arsenic to lepidocrocite.
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DOI：
10.1016/j.jcis.2015.02.047
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发表时间：
2015-06
影响因子：
9.9
通讯作者：
Lin Wang;D. Giammar
中科院分区：
文献类型：
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作者：
Lin Wang;D. Giammar
砷的吸附铁羟基氧化物强烈地依赖于水化学。铁（III）羟基氧化物也可以参与As（III）到As（V）的氧化，这改变了砷的毒性和吸附行为。在批实验中研究了As（III）和As（V）在纤铁矿（γ-FeOOH）上的吸附，探讨了纤铁矿用量、pH、溶解氧的可利用性以及Fe（II）水溶液的存在对吸附的影响。鳞铁矿是一种存在于土壤中的羟基氧化铁，是铁电凝聚法水处理的主要产物之一。一个表面络合模型是能够描述的吸附As（III）和As（V）lepidocrotite在很宽的范围内的条件。溶液中砷的浓度和氧化态在反应过程中进行了测量。在好氧和缺氧条件下，As（III）被氧化为As（V）的系统中，含有lepidocrotite与Fe（II），这种氧化导致整体增强砷吸附在近中性pH值。与氧气的pH值依赖的生成氧化剂的芬顿反应驱动的As（III）氧化。在没有氧的情况下，As（III）可能被纤铁矿中的Fe（III）氧化，后者在与Fe（II）反应时变得更具反应性。
The adsorption of arsenic to iron oxyhydroxides strongly depends on water chemistry. Iron(III) oxyhydroxides can also participate in the oxidation of As(III) to As(V), which changes arsenic’s toxicity and adsorption behavior. As(III) and As(V) adsorption to lepidocrocite (γ-FeOOH) were examined in batch experiments that explored the effects of lepidocrocite dose, pH, availability of dissolved oxygen, and the presence of aqueous Fe(II) on adsorption. Lepidocrocite is an iron oxyhydroxide found in soils, and it is one of the major products of iron electrocoagulation for water treatment. A surface complexation model was able to describe the adsorption of both As(III) and As(V) to lepidocrocite over a broad range of conditions. The concentration and oxidation states of arsenic in solution were measured over the course of the reactions. At both oxic and anoxic conditions, As(III) was oxidized to As(V) in systems that contained lepidocrocite together with Fe(II); this oxidation led to overall enhanced arsenic adsorption at near neutral pH. With oxygen the pH-dependent generation of oxidants from the Fenton reaction drove the As(III) oxidation. In the absence of oxygen the As(III) was probably oxidized by Fe(III) in lepidocrocite that had become more reactive upon reaction with Fe(II).