铁锰双金属氧化物对过硫酸氢钾降解酸性橙7的催化效果

为了发挥均相体系中过渡金属元素对PMS(过硫酸氢钾)的催化效果,同时解决存在的金属离子污染的问题,以AO7(酸性橙7)为目标污染物,研究了采用溶胶-凝胶法(sol-gel method)制备Fe-MnO_x(铁锰双金属氧化物)催化剂催化PMS的效果及降解机理. 结果表明:ρ(Fe-MnO_x)由50 mg/L升至200 mg/L后,35 min时AO7降解率由53.74%升至96.65%；继续升高ρ(Fe-MnO_x),AO7降解率提升效果不明显. 随着ρ(PMS)₀(PMS初始质量浓度)的升高,AO7的降解率变化趋势与之相同；而随着ρ(AO7)₀(AO7初始质量浓度)的升高,AO7降解率有所下降. 分别投加EA(乙醇)、TBA(叔丁醇)这2种捕获剂来验证体系氧化物种时发现,55 min时AO7降解率分别为79.40%和91.33%,氧化体系的主要氧化物种为·SO₄-(硫酸根自由基)和少量·OH(羟基自由基). XRD(X射线衍射)和XPS(X射线光电子能谱)结果显示,Fe-MnO_x催化剂中的Fe、Mn主要以Fe3+、Mn2+、Mn4+ 3种形式存在,Fe、Mn、O 3种元素中,Fe3+、Mn2+、Mn4+、O2-和表面羟基氧的摩尔比分别为20.49%、26.46%、5.60%、32.51%和14.91%. 研究显示,Fe-MnO_x催化剂具有金属离子溶出量低、催化性能良好等优良性能,能够有效催化PMS生成自由基,对水中的污染物具有良好的降解效果. 

Degradation of Acid Orange 7 by Peroxomonosulfate Activated with Fe-MnOx

Bimetallic Fe-Mn oxide (Fe-MnO_x) was prepared using the sol-gel method to take advantage of the ability of Fe and Mn ions to activate peroxymonosulfate (PMS) in a homogeneous system and avoid pollution caused by metal ions. The degradation process and mechanism were investigated for the removal of Acid Orange 7 (AO7) by using Fe-MnO_x as a catalyst to generate powerful radicals from PMS. The effects of ρ(Fe-MnO_x), ρ(PMS)₀ and ρ(AO7)₀ on the degradation of AO7 were tested. The results showed that with the ρ(Fe-MnO_x) from 50 mg/L to 200 mg/L, the degradation rate of AO7 increased from 53.74% to 96.65% at 35 min. However, no significant change in the degradation rate was observed with further increases of ρ(Fe-MnO_x). In addition, the degradation rate of AO7 decreased when ρ(AO7)₀ increased. The reaction of the Fe-MnO_x catalyst-activated PMS was conducted with the addition of one of two probe compounds to detect the generation of reactive oxygen species:ethylalcohol (EA) and tertbutylalcohol (TBA). The degradation rate of AO7 at 55 min was 79.40% by adding EA and 91.33% by adding TBA. Therefore, the oxygen species in the system were identified as mostly sulfate radicals and a small amount of hydroxyl radicals. The results of XRD and XPS indicated that the Fe-MnO_x catalyst consisted of Fe₂O₃, Mn₃O₄ and Mn₅O₈, in which the relative molar quantities of Fe3+, Mn2+, Mn4+, O2+ and surface hydroxyl oxygen were 20.49%, 26.46%, 5.60%,32.51% and 14.91%, respectively. The study indicated that Fe-MnO_x catalyst had a low metallic ion leaching, and good ability to activate PMS and degrade organic pollutants into radicals.