MoS_(2)@FeS_(2)催化电Fenton降解染料废水

Dye wastewater degradation in electro-Fenton system catalyzed by MoS_(2)@FeS_(2)

本研究以掺硼金刚石(boron-doped diamond,BDD)电极为阳极,碳毡(carbon felt,CF)为阴极,并采用简单的一步溶剂热法合成Fe、Mo双金属复合材料,构建电Fenton系统,处理亚甲基蓝(methylene blue,MB)污染物.扫描电子显微(scanning electron microscopy,SEM)和X射线衍射(X-ray diffraction,XRD)表征结果表明MoS_(2)@FeS_(2)双金属硫化物成功合成.实验结果表明MoS_(2)@FeS_(2)表现出优异的催化性能,在电流密度为5 mA·cm^(−2),投加量为0.3 g·L^(−1)时,MB降解效率达94.7%,反应速率常数为0.019 min^(−1),是未投加催化剂的BDD-CF体系(0.008 min^(−1))的2.38倍.此外,该催化剂在pH为3—9的范围内对MB均具有较高的去除率,在实际应用中不需要调节pH.其机理分析表明在整个反应体系中Fe^(2+)的浓度基本上维持在一个稳定的范围,表明该催化剂可通过Mo^(4+)氧化为Mo^(6+)促进Fe^(3+)与Fe^(2+)之间的氧化还原循环,从而可确保体系中有足够多的Fe^(2+)用于有效活化,最大化H_(2)O_(2)的分解效率以促进·OH的产生,20 min时·OH的浓度达到1.43×10^(−5)mol·L^(−1).

In the present study,Fe and Mo bimetallic composite was prepared by one-step solvothermal method and applied in electro-Fenton system with boron-doped diamond(BDD)anode and carbon felt(CF)cathode for methylene blue(MB)degradation.The characterization results by scanning electron microscopy(SEM)and X-ray diffraction(XRD)indicated that bimetallic sulfide MoS_(2)@FeS_(2) had been synthesized successfully.MoS_(2)@FeS_(2) exhibited excellent catalytic performance,with 94.7%MB removed when the current density was 5 mA·cm^(-2) and the dosage is 0.3 g·L^(-1).Degradation rate constant of kobs(0.019 min^(-1))was about 2.38 times compared with BDD-CF system without catalyst(0.008 min^(-1)).Moreover,MB removal rate kept high in the pH range of 3—9,which demonstrated that MoS_(2)@FeS_(2) could be used in practical without the requirement of pH adjustment.The concentration of Fe^(2+)in the whole reaction system was maintained in a stable range.This result was mainly due to the redox cycle between Fe^(3+)and Fe^(2+)through the oxidation of Mo^(4+)to Mo^(6+),which ensured enough Fe^(2+)existing for effective Fenton reaction in the system.Concentration of·OH reached 1.43×10^(-5) mol·L^(-1) at 20 min in the system coming form the efficient decomposition of H_(2)O_(2) produced at cathode.