生物炭负载γ-MnO_(2)纳米复合材料活化过一硫酸盐降解对氯苯酚的性能及机理

Performance and mechanism of biochar doped γ-MnO_(2) nanocomposite activated peroxymonsulfate on 4-Chlorophenol degradation

采用水热法合成了4种不同晶相结构MnO_(2)及生物炭负载γ-MnO_(2)复合纳米材料,并对其活化过硫酸盐(PMS)降解4-CP的性能进行了研究。采用XRD、SEM、EDS以及XRF等手段对不同复合纳米材料进行了表征分析,发现仅有γ-MnO_(2)成功负载到生物炭材料表面形成γ-MnO_(2)@BC复合纳米材料。在优化条件下,γ-MnO_(2)@BC活化PMS体系能在20 min内将10 mg·L^(-1)对氯苯酚完全降解。γ-MnO_(2)@BC对H_(2)PO_(4)^(-)之外的阴离子均表现出较强的抗干扰性。采用自由基捕获及电子自旋共振波谱(ESR)、X射线光电子能谱(XPS)等手段研究了该复合纳米材料活化PMS降解污染物的机理。结果表明,γ-MnO_(2)@BC活化PMS产生的活性氧物种为单线态氧,并发现Mn(III)与Mn(IV)的比值是影响不同晶相二氧化锰催化性能的主要因素。

Four kinds of MnO_(2) with different crystal phase structure and biochar supported γ-MnO_(2)nanocomposites were synthesized by hydrothermal method,and their performance on activating peroxymonsulfate(PMS) and degrading 4-CP was studied.XRD,SEM,EDS and XRF were used to characterize different nano-composite materials.It was found that only γ-MnO_(2) was successfully loaded on the surface of biochar to form γ-MnO_(2)@BC.Under the optimum conditions,10 mg·L^(-1) 4-chlorophenol could be completely degraded by γ-MnO_(2)@BC activated PMS in 20 min.γ-MnO_(2)@BC showed the strong anti-interference against anions except for H_(2)PO_(4)^(-).Finally,the mechanism of reactive oxygen species(ROS) generated by γ-MnO_(2)@BC activated PMS was studied by means of free radical capture,electron spin resonance spectroscopy(ESR) and Xray energy spectroscopy(XPS).The results showed that the ROS produced by γ-MnO_(2)@BC activated PMS was singlet oxygen.It is found that the ratio of Mn(III) to Mn(IV) was the main factor affecting the catalytic performance of MnO_(2) with different crystalline phases.