Hao Xiaolong, Zhou Minghua, Xin Qing, Lei Lecheng
Institute of Environmental Pollution Control Technologies, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang, PR China.
Chemosphere. 2007 Feb;66(11):2185-92. doi: 10.1016/j.chemosphere.2006.08.037. Epub 2006 Dec 12.
To sufficiently utilize chemically active species and enhance the degradation rate and removal efficiency of toxic and biorefractory organic pollutant para-chlorophenol (para-CP), the introductions of iron metal ions (Fe2+/Fe3+) into either pulsed discharge plasma (PDP) process or the PDP process with TiO2 photo-catalyst were tentatively performed. The experimental results showed that under the same experimental condition, the degradation rate and removal efficiency of para-CP were greatly enhanced by the introduction of iron ions (Fe2+/Fe3+) into the PDP process. Moreover, when iron ions and TiO2 were added together in the PDP process, the degradation rate and removal energy of para-CP further improved. The possible mechanism was discussed that the obvious promoting effects were attributed to ferrous ions via plasma induced Fenton-like reactions by UV light irradiation excited and hydrogen peroxide formed in pulsed electrical discharge, resulting in a larger amount of hydroxyl radicals produced from the residual hydrogen peroxide. In addition, the regeneration of ferric ions to ferrous ions facilitates the progress of plasma induced Fenton-like reactions by photo-catalytic reduction of UV light, photo-catalytic reduction on TiO2 surface and electron transfer of quinone intermediates, i.e. 1,4-hydroquinone and 1,4-benzoquinone.
为了充分利用化学活性物种并提高有毒且难生物降解的有机污染物对氯苯酚（对氯酚，para-CP）的降解速率和去除效率，尝试将铁金属离子（Fe2+/Fe3+）引入脉冲放电等离子体（PDP）过程或带有TiO2光催化剂的PDP过程中。实验结果表明，在相同实验条件下，通过将铁离子（Fe2+/Fe3+）引入PDP过程，对氯酚的降解速率和去除效率得到了极大提高。此外，当在PDP过程中同时添加铁离子和TiO2时，对氯酚的降解速率和去除能量进一步提高。探讨了可能的机理，即明显的促进作用归因于亚铁离子通过紫外光照射激发的等离子体诱导类芬顿反应以及脉冲放电中形成的过氧化氢，导致残留过氧化氢产生大量羟基自由基。此外，铁离子再生为亚铁离子通过紫外光的光催化还原、TiO2表面的光催化还原以及醌中间体（即1,4-对苯二酚和1,4-苯醌）的电子转移促进了等离子体诱导类芬顿反应的进行。
