Fe（VI）/CaO2双氧化体系降解水环境中的DMP

Degradation performance of dimethyl phthalate from aqueous environment by dual oxidant of ferrate/calcium peroxide

研究了高铁酸盐(Fe(VI))/过氧化钙(CaO2)联合处理对邻苯二甲酸二甲酯(DMP)的降解性能及机理,分析了共存离子的影响.基于响应面方法中的Box-Behnken实验设计进行了多因素实验,采用二次多项式和逐步回归法拟合了DMP去除率与Fe(VI)投加量、CaO2投加量和反应时间之间的关系,对实验条件进行了优化分析.结果表明,在初始pH值为中性条件下,Fe(VI)/CaO2可以有效去除DMP,降解过程符合准一级动力学模型.当Fe(VI)/CaO2/DMP物质的量比为1.1/4.4/1时,模型预测DMP最大降解率为95.57%,和验证实验得出的降解率90.14%相近,表明该响应面模型具有较好的模拟和预测能力.HCO 3^-和Mg^2+对DMP的降解有一定抑制作用.自由基清除实验结果显示,羟基自由基(HO)和超氧自由基(O 2^-)对DMP的降解具有重要贡献,表明Fe(VI)和CaO2可形成类芬顿试剂协同降解污染物.DMP的主要降解途径包括酯基水解、侧链氧化和苯环的羟基化;主要降解产物为邻苯二甲酸单甲酯,2,5-二羟基苯甲酸,间苯二甲酸,草酸等.

The degradation efficiency and mechanism of ferrite(Fe(VI))/calcium oxide(CaO2)combined treatment on dimethyl phthalate(DMP)were studied.Multi-factor experiments were carried out based on the Box-Behnken experimental design in Response Surface Method.Relationships between the removal rate of DMP and Fe(VI)dosage,CaO2 dosage and reaction time were fitted by quadratic polynomial and stepwise regression method,and the experimental conditions were optimized.DMP could be effectively removed by Fe(VI)/CaO2 under neutral pH conditions,and the degradation process conformed to the pseudo-second-order kinetic model.The maximum degradation rate of DMP predicted by the model reached 95.57%when the molar ratio of Fe(VI)/CaO2/DMP was 1.1/4.4/1,which was close to 90.14%obtained by verification experiments,indicating that the model possessed a good simulation and predictive performance.HCO 3-and Mg(Ⅱ)inhibited the degradation of DMP to a certain extent.-The results of free radical scavenging experiments revealed that hydroxyl radical(HO)and superoxide radical(O2)made significant contributions to the degradation of DMP,demonstrating that Fe(VI)and CaO2 could form Fenton-like reagents to synergistically degrade pollutants.The main degradation pathways of DMP included hydrolysis of ester group,oxidation of side chain and hydroxylation of benzene rings.The main degradation products were monomethyl phthalate,2,5-dihydroxybenzoic acid,isophthalic acid,oxalic acid,etc.