Vis/LaFeO_(3)/PDS复合高级氧化体系降解亚甲基蓝的机制

Mechanism of complex superior oxidation system Vis/LaFeO_(3)/PDS for methylene blue degradation

采用超声辅助溶胶-凝胶法制备对可见光(Vis)有良好响应性的LaFeO_(3)晶体,将其与过二硫酸盐(PDS)结合,构建Vis/LaFeO_(3)/PDS复合高级氧化体系,用以降解亚甲基蓝(MB)。结果表明:在PDS浓度为0.5 mmol/L、LaFeO_(3)投加量为0.5 g/L时,Vis/LaFeO_(3)/PDS体系30 min对质量浓度为30 mg/L的MB的去除率可达92.4%;复合体系对pH值有较强的适应性,Vis、LaFeO_(3)、PDS三者复合,通过提高光生电子-空穴对的分离效率,促进Fe(Ⅱ)/Fe(Ⅲ)的氧化还原循环和氧空位向活性氧自由基的转化,提高了空穴(h^(+))、SO^(-)_(4)·、单线态氧(^(1)O_(2))等活性物质的产生效率和氧化活性能力的发挥。Vis/LaFeO_(3)/PDS体系是光催化和过硫酸盐高级氧化技术的高效结合,其协同效应在废水中难降解有机物的治理方面具有较好的应用前景。

Semiconductor LaFeO_(3) perovskites fabricated via the sol-gel method were used as a peroxydisulfate(PDS)activator for methylene blue(MB)degradation under visible light,and the degradation efficiency and mechanism of organic matter were evaluated.Results indicated that the complex superior oxidation system Vis/LaFeO_(3)/PDS exhibited promising efficiency in the degradation of MB in a wide pH range.Specifically,92.4%of MB with a concentration of 30 mg/L was degraded with the addition of 0.5 g/L LaFeO_(3) and 0.5 mmol/L PDS within 30 min.The combination of the photocatalytic process with the activation performance of LaFeO_(3) to PDS could restrain recombination of the photo-generated electron-hole pairs in the bulk of semiconductor,resulting in efficient redox cycles of Fe(Ⅱ)/Fe(Ⅲ)and conversion from oxygen vacancy to active oxygen,which enhanced production efficiency and oxidative activity capacity of h^(+),SO^(-)_(4)·,and ^(1)O_(2).Therefore,Vis/LaFeO_(3)/PDS is an efficient combination of photocatalysis and sulfate radical-based advanced oxidation technology and makes it a promising method in the treatment of refractory organic pollutants due to its synergistic effect.