Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate-thiosulfate redox couple
Persulfate oxidation for in situ remediation of TCE. I. Activated by ferrous ion with and without a persulfate-thiosulfate redox couple
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DOI：
10.1016/j.chemosphere.2004.01.029
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发表时间：
2004-06-01
期刊：
影响因子：
8.8
通讯作者：
Sperry, KL
中科院分区：
文献类型：
--
作者：
Liang, CJ;Bruell, CJ;Sperry, KL
实验室研究的目的是检查过渡金属离子（例如，亚铁离子，Fe2+）激活过硫酸盐阴离子（S2O82-）的条件，产生一种被称为硫酸盐自由基（SO4-）的强氧化剂，其标准氧化还原电位为2.6 V。中SO4 -。能够就地破坏地下水污染物，如三氯乙烯。在S2O82-/Fe2+/TCE的不同摩尔比下，以Fe2+为活化剂的实验表明，TCE的部分降解几乎是瞬间发生的，然后反应停止。在过量Fe2+的存在下SO4-的破坏或所有Fe2+快速转化为Fe3+限制了系统的最终氧化能力。以小的增量顺序添加Fe2+导致TCE去除效率提高。由此可见，Fe2+在SO4-的生成过程中起着重要的作用。对氧化还原电位（ORP）变化的观察表明，在亚铁离子活化的过硫酸盐体系中加入硫代硫酸钠（Na2S2O3）可以显著降低强氧化条件。假设硫代硫酸盐诱导的还原条件可能将Fe3+转化为较低价态的Fe2+，使Fe2+可用于激活过硫酸盐分解。在亚铁离子活化过硫酸盐氧化TCE的初始停止后，连续添加硫代硫酸盐（S2O32-）可提高TCE的去除率。硫酸盐-硫代硫酸盐氧化还原对活化的亚铁离子在较短的时间内对水体系中的TCE进行了相当彻底的降解。在土浆体系中，TCE的降解速度比水体系慢。(C) 2004 Elsevier Ltd.版权所有。
The objective of the laboratory study is to examine the conditions under which transition metal ions (e.g., ferrous ion, Fe2+) could activate the persulfate anion (S2O82-) to produce a powerful oxidant known as the sulfate free radical (SO4-.) with a standard redox potential of 2.6 V. The SO4-. is capable of destroying groundwater contaminants in situ such as trichloroethylene (TCE). Experiments using Fe2+ as an activator under various molar ratios Of S2O82-/Fe2+/TCE in an aqueous system indicated that partial TCE degradation occurred almost instantaneously and then the reaction stalled. Either destruction of SO4- in the presence of excess Fe2+ or the rapid conversion of all Fe2+ to Fe3+ limited the ultimate oxidizing capability of the system. Sequential addition of Fe2+ in small increments resulted in an increased TCE removal efficiency. Therefore, it appeared that Fe2+ played an important role in generating SO4-.. An observation of oxidation-reduction potential (ORP) variations revealed that the addition of sodium thiosulfate (Na2S2O3) to the ferrous ion activated persulfate system could significantly decrease the strong oxidizing conditions. It was hypothesized that the thiosulfate induced reducing conditions might convert Fe3+ to a lower valence state of Fe2+, making the Fe2+ available to activate persulfate decomposition. The sequential addition of thiosulfate (S2O32-), after the initial stalling of ferrous ion activated persulfate oxidation of TCE, resulted in an improvement in TCE removal. The ferrous ion activated per sulfate-thio sulfate redox couple resulted in fairly complete TCE degradation in aqueous systems in a short time frame. In soil slurry systems, TCE degradation was slower in comparison to aqueous systems. (C) 2004 Elsevier Ltd. All rights reserved.