Oxidation of trichloroethylene by the hydroxyl radicals produced from oxygenation of reduced nontronite
Oxidation of trichloroethylene by the hydroxyl radicals produced from oxygenation of reduced nontronite
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DOI：
10.1016/j.watres.2017.02.012
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发表时间：
2017-04-15
期刊：
影响因子：
12.8
通讯作者：
Liu, Deng
中科院分区：
文献类型：
--
作者：
Liu, Xixiang;Yuan, Songhu;Liu, Deng
含铁（II）硅酸盐矿物的还原被认为是缺氧亚表面中氯化烃（CHCs）衰减的重要机制。由于自然过程和人类活动的影响，地下氧化还原条件经常由缺氧转变为缺氧，但含铁（II）硅酸盐矿物在缺氧条件下诱导CHCs的转化尚不清楚。研究表明，在pH为7.5的条件下，三氯乙烯（TCE）可以被有效氧化，而在缺氧条件下，其还原性可以忽略不计。2 g/L无硝土氧化3 h， TCE（初始为1 mg/L）的最大氧化率为89.6%，还原度为50%。TCE氧化是由于铁（II）在非润土中氧化产生的强氧化羟基自由基（*OH）。边缘的铁（II）优先氧化生成“OH”，内部的铁（II）作为电子池再生边缘的铁（II）。TCE的氧化可以通过化学或生物还原氧化的硅酸盐矿物来维持。我们的发现为CHCs和其他氧化还原活性物质在氧化还原波动环境中的转化提供了一个新的机制。(C) 2017 Elsevier Ltd.版权所有。
Reduction by Fe(II)-bearing silicate minerals has been proposed as an important mechanism for the attenuation of chlorinated hydrocarbons (CHCs) in anoxic subsurfaces. The redox condition of subsurface often changes from anoxic to oxic due to natural processes and human activities, but little is known about the transformation of CHCs induced by Fe(II)-bearing silicate minerals under oxic conditions. This study reveals that trichloroethylene (TCE) can be efficiently oxidized during the oxygenation of reduced nontronite at pH 7.5, whereas the reduction was negligible under anoxic conditions. The maximum oxidation of TCE (initially 1 mg/L) attained 89.6% for 3 h oxygenation of 2 g/L nontronite with 50% reduction extent. TCE oxidation is attributed to the strongly oxidizing hydroxyl radicals (*OH) produced by the oxygenation of Fe(II) in nontronite. Fe(II) on the edges is preferentially oxygenated for "OH production, and the interior Fe(II) serves as an electron pool to regenerate the Fe(II) on the edges. Oxidation of TCE could be sustainable through chemically or biologically reducing the oxidized silicate minerals. Our findings present a new mechanism for the transformation of CHCs and other redox-active substances in the redox-fluctuation environments. (C) 2017 Elsevier Ltd. All rights reserved.