氧化铜活化过硫酸盐的界面反应机理
Interfacial reaction mechanism of copper oxide activating persulfate
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摘要: 本文以苯酚为降解对象，系统性研究了氧化铜（CuO）活化过二硫酸盐（PDS）与过一硫酸盐（PMS）降解苯酚的界面反应机理.结果表明，CuO可高效活化PDS和PMS降解苯酚，电子顺磁共振（EPR）结果表明CuO/PDS体系中的活性物种有SO4·-、·OH和O2·-，而CuO/PMS体系中主要存在O2·-和1O2，猝灭实验结果表明CuO/PMS体系中O2·-起到了关键作用.CuO/PDS和CuO/PMS体系均可选择性降解具有给电子官能团的有机物.在CuO/PDS体系中，主要活化机理为富电子有机物通过取代表面羟基吸附于CuO表面，与CuO发生电子传递产生苯氧自由基，进一步可活化PDS和O2产生SO4·-、·OH、O2·-等活性物种实现对有机物的降解.而在CuO/PMS体系中，PMS通过取代CuO表面羟基产生亚稳态中间体，与PMS及O2·-反应生成1O2实现对苯酚的降解，虽然体系中也存在与CuO/PDS体系中类似的苯氧自由基活化过程，但其对有机物降解的贡献较小.Abstract: In this paper, the mechanisms of peroxydisulfate (PDS) and peroxydisulfate (PMS) activating by commercial cupric oxide (CuO) were systematically studied. The results showed that CuO could effectively activate PDS and PMS to degrade phenol. The EPR results showed the reactive species in the CuO/PDS system involved SO4·-,·OH and O2·-, while they were O2·- and 1O2 in the CuO/PMS system. The results of quenching experiments showed that O2·- played a key role in the CuO/PMS system. Further studies showed that both two systems would selectively degrade those organic compounds with electron donating functional groups. Thus, the activation mechanism in the two reaction systems were therefore proposed, in the CuO/PDS system, phenoxy radicals could be formed between CuO and phenol, then PDS was activated by phenoxy radicals to produce SO4·-、·OH and O2·- for phenol degradation. As in the CuO/PMS system, PMS tended to form metastable intermediates by substituting hydroxyl groups on the surface of CuO, and intermediates further reacted with PMS and O2·- to generate 1O2. PMS could be also activated by phenoxy radical as the reaction mechanism in the CuO/PDS system, but its contribution was negligible.
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Key words:
- copper oxide /
- peroxymonosulfate /
- peroxydisulfate /
- phenol /
- Fenton-like system
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