Efficient peroxydisulfate activation process not relying on sulfate radical generation for water pollutant degradation.
Efficient peroxydisulfate activation process not relying on sulfate radical generation for water pollutant degradation.
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DOI：
10.1021/es501218f
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发表时间：
2014-05
影响因子：
11.4
通讯作者：
Tao Zhang;Yin Chen;Yuru Wang;Julien Le Roux;Yang Yang-Yang;J. Croué
中科院分区：
文献类型：
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作者：
Tao Zhang;Yin Chen;Yuru Wang;Julien Le Roux;Yang Yang-Yang;J. Croué
过二硫酸盐(PDS)是治理地下水污染和有毒工业废水的理想氧化剂。由于PDS的活性较低，因此需要对其进行活化才能应用。目前的活化过程往往会产生硫酸根作为实际的氧化剂，非选择性地氧化有机物和卤化物阴离子，降低了PDS的氧化能力，并产生有毒的卤化产物。在这里，我们报道了氧化铜(CuO)可以在温和的条件下有效地活化PDS，而不产生硫酸根。对于模型化合物2，4-二氯苯酚(2，4-DCP)，在中性pH条件下，PdS/CuO偶联反应最为有效。在空床接触时间为0.55min的连续流动反应中，当PdS/2，4-μ摩尔比为1和4时，2，4-DCP(初始摩尔比为20)和可吸附有机氯(AOCL)的脱色率分别达到90%和90%以上。基于动力学研究和表面表征，提出了PDS首先被CuO通过外球相互作用活化的限速步骤，然后与溶液中存在的2，4-DCP发生快速反应。在地下水/工业废水中普遍存在氯离子的情况下，PDS/CuO氧化比硫酸盐自由基氧化具有更高的2，4-DCP降解能力和避免了高氯化降解产物的形成，因此具有明显的优势。这项工作为PDS活化去除污染物提供了一种新的途径。
Peroxydisulfate (PDS) is an appealing oxidant for contaminated groundwater and toxic industrial wastewaters. Activation of PDS is necessary for application because of its low reactivity. Present activation processes always generate sulfate radicals as actual oxidants which unselectively oxidize organics and halide anions reducing oxidation capacity of PDS and producing toxic halogenated products. Here we report that copper oxide (CuO) can efficiently activate PDS under mild conditions without producing sulfate radicals. The PDS/CuO coupled process is most efficient at neutral pH for decomposing a model compound, 2,4-dichlorophenol (2,4-DCP). In a continuous-flow reaction with an empty-bed contact time of 0.55 min, over 90% of 2,4-DCP (initially 20 μM) and 90% of adsorbable organic chlorine (AOCl) can be removed at the PDS/2,4-DCP molar ratio of 1 and 4, respectively. Based on kinetic study and surface characterization, PDS is proposed to be first activated by CuO through outer-sphere interaction, the rate-limiting step, followed by a rapid reaction with 2,4-DCP present in the solution. In the presence of ubiquitous chloride ions in groundwater/industrial wastewater, the PDS/CuO oxidation shows significant advantages over sulfate radical oxidation by achieving much higher 2,4-DCP degradation capacity and avoiding the formation of highly chlorinated degradation products. This work provides a new way of PDS activation for contaminant removal.