新型Z型异质结增强光芬顿降解水中氯酚

Novel Z-type heterojunction enhancing photo-Fenton degradation of aqueous chlorophenols

增强光生载流子分离和Fe(Ⅲ)/Fe(Ⅱ)循环是增强光芬顿催化剂性能的关键。本研究采用低温煅烧法制备系列新型Z型异质结Fe_(2)O_(3)-TiO_(2)-x,利用X射线衍射、扫描电子显微镜和透射电子显微镜等表征方法证实Fe_(2)O_(3)纳米簇成功结合在TiO_(2)表面。以2,4-二氯苯酚(2,4-DCP)为模型污染物评估系列催化剂的光芬顿性能,发现UV-Vis/H_(2)O_(2)/Fe_(2)O_(3)-TiO_(2)-200体系最佳,可在12 min内实现完全降解。而且光照30 min后,2,4-DCP的矿化率可达91.5%、脱氯率可达100%。采用液质联用仪分析2,4-DCP的降解路径,主要经过脱氯和开环等过程,并发现其降解中间产物的毒性有效降低。深入分析新型Z型异质结增强光芬顿的机制,主要源自于内建电场驱动载流子分离、加速Fe(Ⅲ)/Fe(Ⅱ)循环。此外,UV-Vis/H_(2)O_(2)/Fe_(2)O_(3)-TiO_(2)-200体系适用于酸性和中性、有机酸和高浓度阴离子共存的复杂水体,可高效、深度降解水中氯酚类污染物,具有良好的应用潜力。

Enhancing photogenerated-carriers separation and Fe(Ⅲ)/Fe(Ⅱ) cycling are the key to improve the performance of photo-Fenton catalyst.In this study,a series of novel Z-type heterojunction Fe_(2)O_(3)-TiO_(2)-x were prepared by low temperature calcination method,the Fe_(2)O_(2) nanoclusters were successfully anchored on TiO_(2)(surface) by X-ray diffraction,scanning electron microscopy and transmission electron microscopy.Taking 2,4-dichlorophenol(2,4-DCP) as the model pollutant,it was found that UV-Vis/H_(2)O_(2)/Fe_(2)O_(3)-TiO_(2)-200 system exhibited the optimal photo-Fenton performance,in which 2,4-DCP was completely degraded within 12 min illumination.The mineralization and dechlorination rates of 2,4-DCP reached 91.5% and 100% after 30 min illumination,respectively.The degradation path of 2,4-DCP was analyzed via Liquid chromatography-mass spectrometry instrument,the dechlorination and ring-opening process was identified,and the toxicity of the degradation intermediates was effectively reduced.The enhanced photo-Fenton mechanism of Z-type heterojunction mainly resulted from the internal electric field driven-carrier separation and increased Fe(Ⅲ)/Fe(Ⅱ) cycle.In addition,the UV-Vis/H_(2)O_(2)/Fe_(2)O_(3)-TiO_(2)-200 system could efficiently degrade chlorophenols in the complex water body with the coexistence of organic acids and high concentration of anions under acidic and neutral conditions,which exhibited promising potential for application.