亚铁离子活化过二硫酸钠降解亚甲基蓝研究

Degradation of methylene blue in ferrous ion activated sodium persulfate system

通过亚铁离子活化过二硫酸钠的方法产生强氧化性的活性物质,本文研究其降解亚甲基蓝的特性和相关机制.结果表明,在亚铁离子/过二硫酸钠体系中,亚甲基蓝能被降解,降解效率随亚铁离子浓度增大而增大;随着过二硫酸钠浓度的增加,降解效率先增加后减少.通过考察叔丁醇和甲醇淬灭实验中亚甲基蓝降解效率的变化,得出硫酸根自由基和羟基自由基是降解亚甲基蓝的活性物质.研究还发现,常用的亚铁离子螯合剂并没有提高降解效率,这是因为在和自由基的反应中,螯合剂和亚甲基蓝产生了竞争反应.最后通过紫外可见光光谱实验,验证了亚甲基蓝能在亚铁离子/过二硫酸钠体系中被有效的降解.在查阅文献基础上,文章还比较了该体系降解亚甲基蓝和其他污染物不同的特点和共同的规律,并提出相应的机制.该成果可以对过二硫酸类高级氧化技术的发展有一定的促进作用.

The degradation characteristics and mechanisms of methylene blue were investigated in ferrous ion activated sodium persulfate system via free radical oxidation.Methylene blue can be effectively degraded and removal efficiency increases with increasing ferrous ion concentration.However,degradation efficiency first increased and then decreased with increasing sodium persulfate concentration. Radical scavenger experiments of methanol and tert-butyl alcohol revealed that sulfate and hydroxyl radicals were the oxidizing substances responsible for removal of methylene blue.In order to improve degradation efficiency,commonly used ferrous iron chelating agents were added.It was found that chelating agents competed with methylene blue in radical oxidation.UV-visible absorbance spectral changes proved that methylene blue could be degraded effectively in this system.Differences and common characteristics of methylene blue and other compound degradation in this oxidation system were noted and mechanisms of degradation were proposed.This work might facilitate the development of persulfate based advanced oxidation processes.