双阳极氧化与日光/派生过硫酸盐氧化复合降解刚果红

阳极氧化体系中引入了过硫酸盐的自动生成机制。文中主要研究了Ti/Ru-Ir氧化物涂层电极和Pt双阳极体系中过硫酸盐的生成与刚果红的降解规律。实验证明，在阳极区过硫酸盐的生成与刚果红的降解之间存在竞争关系，Ti/Ru-Ir氧化物涂层阳极有利于刚果红的降解，Pt阳极有利于过硫酸盐的生成；刚果红的降解速率与Ti/Ru-Ir氧化物涂层阳极电流密度、SO2-4浓度呈正比，与pH呈反比；过硫酸盐的产量与电流密度、SO2-4浓度、pH密切相关，其中电流密度的影响最大，只有当Pt阳极电流密度高于Ti/Ru-Ir氧化物涂层阳极电流密度200倍以上时，SO2-4才可有效转化成S2O2-8。电解体系中生成的过硫酸盐在模拟日光照射下可对有机物进一步降解。文中还研究了日光/过硫酸盐法的降解机理。

Degradation of Congo red by a combined oxidation system of two anodes and sunlight/derivative persulfate

The auto-generation mechanism of persulfate was introduced into an anodic oxidation system.The formation of persulfate and the degradation of Congo red in a double anode system consisting of Ti/Ru-Ir oxide coated and Pt anodes were investigated in this paper.The results indicated that there was a competition relationship between them in the anode zone.The double anodes were favorable for Congo red degradation and persulfate formation.The degradation rate of Congo red was proportional to anode current density at coated metal oxide anode and SO2-4concentration,but inversely proportional to pH.The yield of persulfate was closely related to the current density,SO2-4 concentration and pH.Among them the current density was main factor.SO2-4 could be transformed effectively into S2O2-8 only when the current density was higher over 200 times at Pt-anode than at Ti/Ru-Ir oxide coated one.The persulfate produced in the electrolysis system can decompose organics in the solution under irradiation of simulated sunlight.The degradation mechanism of combined sunlight and persulfate was also investigated.The results showed that there could be intermediate materials of quinonoids imine type during degradation,which is of photosensitivity and more sensitive to visible light.So,it can induce photosensitive reaction under irradiation of visible light,resulting in generation of singlet oxygen1O2 and peroxy radical O-2 ·.These species can promote formation of hydroxyl radicals ·OH and sulfate radicals SO-4 · at low pH(acidic)condition,which can produce the species with strong oxidizability and make this system easy degrade organics.