以介孔分子筛MCM-48为载体, 采用水热法制备了负载磷钨酸H3PW12O40(HPW)的多金属氧酸盐催化剂HPW/MCM-48。利用傅里叶变换红外光谱(FT-IR)、 小角度X射线粉末衍射(XRD)、 氮气吸附检测和高分辨透射电子显微镜(HRTEM)对其结构进行了表征, 并以农药吡虫啉和百草枯为对象, 考察了所制备的HPW/MCM-48的光催化降解活性。结果表明, 采用水热法制备的催化剂保持了MCM-48的介孔分子筛结构和HPW的Keggin结构, 比表面积783.35 m2·g-1, 孔体积1.46 cm3·g-1, 平均孔径2.76 nm, 相比于母体HPW, HPW/MCM-48的比表面积大大增加; 在365 nm紫外光下反应14h后, 20 mg剂量HPW/MCM-48催化剂能使50 mL, 10 mg·L-1吡虫啉和百草枯的降解率分别达57.38%和63.79%, 而HPW对两种农药的降解率在25%左右, 空白组降解率均低于5%, 说明负载后HPW对两农药的降解活性显著增强。动力学考察表明, HPW/MCM-48对农药降解过程符合一级动力学方程, 对吡虫啉和百草枯这两种农药的降解速率常数Ka分别为0.089和0.117 h, 半衰期t1/2为7.8和5.9 h。

A composite catalyst H3PW12O40/MCM-48 was prepared by loading photocatalyst phosphotungstic acid H3PW12O40 (HPW) to molecular sieve MCM-48 by impregnation method, and its structure was characterized by Fourier transform infrared (FT-IR) spectra, small angle X-ray diffraction (XRD) patterns, nitrogen adsorption analysis and High-resolution transmission electron microscopy (HRTEM) analysis. Photocatalytic degradation activities of HPW/MCM-48 against pesticides imidacloprid and paraquat were evaluated under UV radiation (365 nm). The results show that HPW/MCM-48 maintains the mesoprous molecular sieve structure of MCM-48 and the Keggin structure of HPW, while the BET surface area is 793.35 m2·g-1, pore volume is 1.46 cm3·g-1, average pore diameter is 2.76 nm, suggesting loading HPW on MCM-48 is a considerable way to improve its surface area. After 14 h UV irradiation (365 nm), 57.38% imidacloprid and 63.79% paraquat were degraded by 20 mg HPW/MCM-48 catalyst, while HPW and blank group degraded the two pesticides at the degradation rate of about 25% and 5%, respectively. Implying loading on MCM-48 could greaterly improve the degradation activity of HPW. The reslut of degradation kinetics show that, the degradation process of HPW/MCM-48 fits first order kinetics equation. The rate constant Ka of HPW/MCM-48 toward imidacloprid and paraquat are 0.089 h and 0.117 h, with the half-life t1/2 of 7.8 h and 5.9 h, respectively.