Abstract:

A composite activated carbon fiber(ACF) cathode Mn₃O₄/ACF, which was prepared using a cyclic voltammetry method, was employed in a heterogeneous electro-Fenton-like system for the degradation of a model dye, methylene blue(MB), with no other reagents added.The decolorization ratio and the mineralization of MB in the different pH were investigated and the active oxygen species involved in the system were also detected.The experiment results showed that when solution pH was set as 3.0, 5.0 and 7.0, the decolorization ratio reached to 97.3%, 99.9% and 99.8%, respectively, and TOC removal achieved to 73.4%, 88.6% and 80.4%, indicating the extensive feasibility of the system in broad pH range.The results of detection of the active oxygen species demonstrated that H₂O₂ was electro-produced at the surface of cathode.The hydroxyl free radical·OH generated by the Fenton-like reaction of Mn₃O₄ with H₂O₂ was responsible to the degradation of MB.The superoxide radical O₂·^- was also proved playing important role in decolorization of MB.The mechanism of degradation of the contaminant by this heterogeneous electro-Fenton-like system was preliminarily discussed.

Key words: electrolysis, catalyst, composite, electro-Fenton-like, free radical, methylene blue, degradation

摘要：

用电化学方法将Mn₃O₄负载于活性炭纤维（activated carbon fiber，ACF）表面制备了Mn₃O₄/ACF复合阴极，与铂丝阳极构成了异相类电芬顿体系对模型污染物亚甲基蓝（MB）进行降解，考察了该体系在不同pH条件下对MB去除率，并对体系中的活性氧物种进行了检测，初步探讨了降解机理。实验结果表明，在pH 3.0、pH 5.0和pH 7.0时亚甲基蓝脱色率分别达到97.3%、99.9%、99.8%，pH5.0时TOC去除率达到88.6%，pH 7.0和pH 3.0时也分别达到了80.4%和73.4%，拓宽了电芬顿反应的适宜pH范围。体系中活性氧物种的检测结果表明，氧在阴极电还原产生H₂O₂，并与Mn₃O₄反应生成羟基自由基·OH，同时，氧的一电子还原产物超氧自由基O₂·^-也对阴极表面污染物的脱色有重要贡献。

关键词: 电解, 催化剂, 复合材料, 类电芬顿, 自由基, 亚甲基蓝, 降解