Effect of chelating agent on the oxidation rate of PCP in the magnetite/H2O2 system at neutral pH
Effect of chelating agent on the oxidation rate of PCP in the magnetite/H2O2 system at neutral pH
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DOI：
10.1016/j.molcata.2009.06.016
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发表时间：
2009-09
影响因子：
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通讯作者：
Xiaofei Xue;K. Hanna;C. Despas;Feng Wu;N. Deng
中科院分区：
文献类型：
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作者：
Xiaofei Xue;K. Hanna;C. Despas;Feng Wu;N. Deng
在中性pH条件下，考察了螯合剂对磁铁矿（Fe3O4）存在下芬顿非均相氧化五氯酚（PCP）反应速率的影响，选择了EDTA、CMCD、草酸盐、酒石酸盐、柠檬酸盐和琥珀酸盐6种螯合剂（CA）。五氯苯酚的氧化速率在芬顿样系统中显着提高，通过使用螯合剂在中性pH值。这一观察结果得到了支持的氯化物的降解产生的浓度增加。发现非均相氧化速率的增强因子与溶解铁量的增强因子不相关。而溶解铁对均相反应的促进作用则有助于整体氧化速率的提高。在均相芬顿体系（溶解态Fe2+或Fe3+）中，EDTA驱动的芬顿反应表现出最高的氧化速率，而在非均相芬顿体系（Fe3O4）中，草酸的氧化效率似乎更高。事实上，EDTA比草酸盐更强地结合到磁铁矿表面，并且比H2O2或PCP更积极地竞争吸附在表面活性位上。当EDTA预先吸附在催化剂表面上时，观察到H2O2分解速率值降低。催化剂表面具有铁位的氧化剂的表面机制似乎是非均相芬顿体系中的限速步骤。
The effect of chelating agents on the Fenton heterogeneous oxidation rate of pentachlorophenol (PCP) in the presence of magnetite (Fe3O4) was investigated in opened batch reactor at neutral pH. Six kinds of chelating agents (CA) were selected including EDTA, CMCD, oxalate, tartrate, citrate and succinate. The PCP oxidation rate in the Fenton-like system was significantly improved by using chelating agents at neutral pH. This observation was supported by the increased concentration of chloride produced by the degradation of PCP. The enhancement factor of heterogeneous oxidation rate was found to be not correlated with that of dissolved iron amount. However, the propagation of homogeneous reaction by the dissolved iron contributed to the improvement of the whole oxidation rate. In homogeneous Fenton system (dissolved Fe2+or Fe3+), EDTA-driven Fenton reaction showed the highest oxidation rate, while oxalate seems to be more efficient in heterogeneous Fenton system (Fe3O4). In fact, EDTA can bind more strongly than oxalate to magnetite surface and compete more actively than H2O2or PCP for the sorption on the surface active sites. Decrease in H2O2decomposition rate value was observed when EDTA is previously adsorbed on the catalyst surface. The surface mechanism of oxidant with iron sites on the catalyst surface appears to be the rate-determining step in heterogeneous Fenton system.