pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene
pH dependence of persulfate activation by EDTA/Fe(III) for degradation of trichloroethylene
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DOI：
10.1016/j.jconhyd.2009.02.008
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发表时间：
2009-05-12
影响因子：
3.6
通讯作者：
Chen, Chi-Chin
中科院分区：
文献类型：
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作者：
Liang, Chenju;Liang, Ching-Ping;Chen, Chi-Chin
游离亚铁离子活化的过硫酸盐(S(2)O(8)(2-))生成硫酸根(SO(4)(-))氧化三氯乙烯(TCE)的能力受到过量Fe(2+)清除SO(4)(-)和Fe(2+)快速转化为Fe(3+)的限制。研究了乙二胺四乙酸(EDTA)络合Fe(3+)在pH值为3、7和10的条件下活化过硫酸盐对水相中三氯乙烯(TCE)的降解作用。在EDTA/Fe(3+)活化的过硫酸盐体系中，WE的存在可以加速过硫酸盐和EDTA的降解，这是因为在较高的pH条件下，铁循环活化过硫酸盐。随着pH值的升高，三氯乙烯、S(2)O(8)(2-)和乙二胺四乙酸二乙酯的准一级反应速率常数增加，氯的生成增加。因此，在pH值为10的条件下，不同EDTA/Fe(3+)摩尔比的实验结果表明，1/1的EDTA/Fe(3+)摩尔比在反应初期的降解率明显高于其他摩尔比的结果。EDTA/Fe(3+)摩尔比为1：1时，过硫酸盐投加量越大，TCE降解率越高。然而，过硫酸盐浓度的增加也可能导致过硫酸盐消耗率的增加。(C)2009爱思唯尔B.V.保留所有权利。
The ability of free ferrous ion activated persulfate (S(2)O(8)(2-)) to generate sulfate radicals (SO(4)(-)) for the oxidation of trichloroethylene (TCE) is limited by the scavenging of SO(4)(-) with excess Fe(2+) and a quick conversion of Fe(2+) to Fe(3+). This study investigated the applicability of ethylene-diamine-tetra-acetic acid (EDTA) chelated Fe(3+) in activating persulfate for the destruction of TCE in aqueous phase under pH 3, 7 and 10. Fe(3+) and EDTA alone did not appreciably degrade persulfate. The presence of WE in the EDTA/Fe(3+) activated persulfate system can induce faster persulfate and EDTA degradation due to iron recycling to activate persulfate under a higher pH condition. Increasing the pH leads to increases in pseudo-first-order-rate constants for TCE, S(2)O(8)(2-) and EDTA degradations, and Cl generation. Accordingly, the experiments at pH 10 with different EDTA/Fe(3+) molar ratios indicated that a 1/1 ratio resulted in a remarkably higher degradation rate at the early stage of reaction as compared to results by other ratios. Higher persulfate dosage under the EDTA/Fe(3+) molar ratio of 1/1 resulted in greater TCE degradation rates. However, increases in persulfate concentration may also lead to an increase in the rate of persulfate consumption. (C) 2009 Elsevier B.V. All rights reserved.