硅藻土负载α-MnO_(2)纳米复合材料催化臭氧氧化溴氨酸钠的性能及机理

Performance and mechanism of diatomite-loadedα-MnO_(2) nanocomposites for catalytic ozone oxidation of bromamine acid sodium salt

采用水热法成功合成了4种晶相结构的MnO_(2)及将其负载在硅藻土上的纳米复合材料,并对其催化臭氧氧化降解溴氨酸钠(BAA)性能进行了详细研究。采用XRD、SEM、CV、EIS等手段对材料进行表征,α-MnO_(2)/DE更低的极化电阻以及更快地电子转移效率是其性能优异的原因。单因素实验结果表明,α-MnO_(2)/DE催化臭氧氧化反应体系能在30 min内将50 mg·L^(-1)BAA完全降解。通过对反应前后XPS表征、自由基淬灭实验、ESR分析研究该反应体系的催化机理。结果表明,Mn(Ⅲ)作为反应活性位点使O_(3)吸附并活化产生ROS,同时该体系的主要活性氧物种为·OH。此外,离子干扰实验和循环实验证明该新型催化剂具有优异的稳定性和广阔的应用前景。

MnO_(2) with four types of crystalline phase structure and the composite nanomaterials of these MnO_(2)loaded on diatomite were successfully synthesized by a hydrothermal method,and a detailed research was conducted on their performance in catalytic ozonation and degradation of bromamine acid sodium salt(BAA).The materials were characterized by XRD,SEM,CV and EIS,of whichα-MnO_(2)/DE presented the lower polarization resistance and the faster electron transfer efficiency,which contributed to its excellent performance.Single factor experiments showed that theα-MnO_(2)/DE-catalyzed ozone oxidation system could degrade 50mg·L^(-1)BAA by 100%within 30 min.XPS characterization before and after the reaction,free radical quenching experiment,and ESR analysis was used to identify the catalytic mechanism of the system.The results showed that Mn(Ⅲ)acted as the reactive site to adsorb O_(3) molecules and activate them to produce ROS,at the same time the main reactive oxygen species in the system was·OH.In addition,ionic interference and cycling experiments demonstrated that the novel catalyst had an excellent stability and promising application for organic pollutant degradation.