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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783.35m2·g-1,孔体积1.46cm3·g-1,平均孔径2.76nm,相比于母体HPW,HPW/MCM-48的比表面积大大增加;在365nm紫外光下反应14h后,20mg剂量HPW/MCM-48催化剂能使50mL,10mg·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0.117h,半衰期t1/2为7.8和5.9h。
HPM / MCM-48, a polyoxometallate catalyst supported on H3PW12O40 (HPW), was prepared by hydrothermal method using mesoporous MCM-48 as carrier. Its structure was characterized by Fourier transform infrared spectroscopy (FT-IR), small angle X-ray powder diffraction (XRD), nitrogen adsorption detection and high resolution transmission electron microscopy (HRTEM) Object, investigated the photocatalytic degradation activity of the prepared HPW / MCM-48. The results showed that the catalyst prepared by hydrothermal method retained the Keggin structure of MCM-48 mesoporous molecular sieve and HPW, the specific surface area of 783.35m2 · g-1, the pore volume of 1.46cm3 · g-1, the average pore diameter of 2.76nm, the phase The specific surface area of HPW / MCM-48 was significantly higher than that of HPW / MCM-48. The degradation rate of 50mL, 10mg · L-1 imidacloprid and paraquat Up to 57.38% and 63.79%, respectively, while the HPW degradation rate of two pesticides was about 25% and the degradation rate of the blank group was less than 5%, indicating that HPW degradation activity of two pesticides was significantly enhanced after the load. Kinetic studies indicated that the degradation process of HPW / MCM-48 agrees with the first-order kinetic equation. The degradation rate constants Ka, Imidacloprid and Paraquat are 0.089 and 0.117 h respectively, and the half-life t1 / 2 is 7.8 and 5.9 h