微波辅助Pb/ZrO_x光催化降解水中的对硝基苯酚

Microwave-assisted photocatalytic degradation of PNP over Pb/ZrO_x

采用十六烷基三甲基溴化铵(CTAB)辅助水热法制备了适用于微波辅助光催化体系的高效Pb/ZrO_x催化剂,并对其进行了XRD、XPS、BET和SEM等表征,其XPS结果显示在Pb/ZrO_x表面,Zr以+2、+3和+4三种价态共存。考察了微波辅助光催化氧化(MW/PC)对硝基苯酚(PNP)过程中,微波辐照功率、催化剂投加量、溶液初始pH和PNP初始浓度对PNP去除效果的影响,得到最优操作条件为,PNP初始pH值为5,催化剂投加量为1.0 g·L^(-1),微波辐照功率为200 W。此条件下,初始浓度为50 mg·L^(-1)的PNP溶液反应12min后,PNP转化率达95%,TOC去除约70%。并且,Pb/ZrO_x能够在重复使用5次的情况下仍保持较好的活性。比较了MW、PC和MW/PC 3种体系,得到MW/PC体系将PNP去除率从单独PC体系的48%提高至95%。微波与紫外光存在良好的协同作用,MW/PC能够快速、高效去除水中PNP,为微波辅助光催化氧化去除污染物提供理论基础。

A Pb / ZrO_xcatalyst was synthesized using a surfactant-assisted hydrothermal method for a microwaveassisted photocatalytic（ MW / PC） process. X-ray photoelectron spectroscopy（ XPS）,X-ray diffraction（ XRD）,scanning electron microscopy（ SEM） techniques and Brunauer – Emmett – Teller（ BET） surface area analysis method,were adopted to characterize the as-prepared Pb / ZrO_x. Three valences（ ＋ 2, ＋ 3,and ＋ 4） were found to coexist on the surface of the Pb / ZrO_xcatalyst based on the XPS results. The effects of microwave power,catalyst dosage,initial pH,and initial p-nitrophenol（ PNP） concentration on the degradation of PNP were investigated in detail,and the optimal values of these operating parameters were 200 W,1. 0 g·L^-1,about 5,and50 mg·L^-1. Under these optimal conditions,the removal efficiency of PNP reached 95% and TOC removal was70% after 12 min of reaction. Moreover,the Pb / ZrO_xcatalyst could be used repeatedly up to 5 cycles without significant loss in its catalytic activity. Compared to the microwave（ MW） and photocatalysis（ PC） processes,PNP conversion using the MW / PC process was from 48%（ PC） to 95% higher. In short,a significant synergistic effect existed between microwaves and photocatalysis. In the MW / PC process,higher degradation efficiency was obtained compared to the traditional PC process.