施氏矿物/H_2O_2体系对废水中甲基橙的降解性能及机理

Performance and mechanism of oxidative degradation of methyl orange in wastewater by Schwertmannite/H_2O_2 system

为了考察施氏矿物/H2O2体系对废水中甲基橙的氧化降解性能,通过化学法合成施氏矿物,分析了溶液初始pH、施氏矿物和H2O2投加量、共存阴离子等因素对甲基橙降解的影响,并对降解机理进行了初步探讨。结果表明:当溶液初始pH为3.0～5.0、甲基橙浓度为10 mg·L-1、施氏矿物和H2O2投加量分别为1.0 g·L-1和800 mg·L-1时,经过12 h反应后,废水中甲基橙降解率可达97.0%;而当初始溶液pH=6.0时,甲基橙的降解被抑制,降解率仅为52.4%。无机阴离子对甲基橙降解率的影响微弱,在Cl-、NO3-、SO24-共存条件下,12 h反应后,甲基橙降解率仍可达90.0%以上。施氏矿物重复利用性能良好,在经6个反应周期后,甲基橙的降解率仍可达93.4%。施氏矿物/H2O2体系可有效拓宽传统Fenton反应的pH范围,该体系对甲基橙具有良好的降解性能,降解过程遵循羟基自由基机理。

In this study,a type of chemosynthetic Schwertmannite and H2 O2 were used to facilitate methyl orange(MO)degradation in organic wastewater.The effects of initial pH of solution,Schwertmannite and H2 O2 doses,and coexisting anions on the degradation process were analyzed,and the degradation mechanism was preliminarily investigated.The results showed that MO degradation rate reached 97.0%after 12 h oxidation reaction under the conditions of initial pHs from 3.0 to 5.0,initial MO concentration of 10 mg·L-1 in wastewater,1.0 g·L-1 Schwertmannite and 800 mg·L-1 H2 O2 dosages.However,when the initial p H was 6.0,MO degradation was strongly inhibited and its degradation rate was only 52.4%.The inorganic anions had slight effects on MO degradation rate which could still reach over 90.0%after 12 h reaction when inorganic anions(Cl-,NO3-,SO24-)were coexisted.After six reactive cycles,the reused Schwertmannite and H2 O2 could degrade 93.4%MO,indicating a good durability of Schwertmannite.This study showed that Schwertmannite/H2 O2 system effectively broadens the pH range of the traditional Fenton reaction,exhibits a good MO degradability,and the degradation process follows hydroxyl radical mechanism.