Heterogeneous photocatalysts consisting of phosphotungstic acid or silicotungstic acid immolilized on mesoporous molecular sieve MCM-41 were prepared and characterized by FTIR, X-ray diffraction, nitrogen adsorption and high resolution transmission electron microscope (HRTEM). The photocatalytic activities of the prepared H3PW12O40/MCM-41 or H4SiW12O40/MCM-41 were examined by photodegradation of pesticide paraquat. Results show that the prepared composites have large specific surface area and uniform mesopores, the Keggin structure of two parent heteropoly acids was retained after loading on MCM-41. Both of the prepared photocatalysts exhibit high activityies under irradiation of 365 nm monochromatic Light. For 50 mL paraquat (10 mg · L-1), conversions of paraquat using 15 mg H3PW12O40/MCM-41 or H4SiW12O40/MCM-41 as catalysts after 14 hours' irradiation are 92. 0% and 87. 6% respectively. The photocatalytic reactions are in accordance with the first order kinetics equation, and the half lives of the reactions are 3. 6 h and 4. 7 h respectively.%采用浸渍法将具有光催化活性的多金属氧酸盐( polyoxometalate,POM)磷钨酸和硅钨酸负载到介孔分子筛MCM-41,制备了H3PW12O40/MCM-41和H4SiW12O40/MCM-41两种复合材料,以红外光谱(FT-IR)、X射线衍射(XRD)、N2吸附、高分辨透射电镜(HRTEM)等分析手段对所合成的多酸-分子筛复合材料进行了表征,并以农药百草枯的光催化降解考察了复合材料的光催化活性.所合成的复合材料同时保留了母体多酸的Keggin特征结构和载体MCM-41分子筛均匀的六方孔道结构,比表面积超过200 m2·g-1.用于农药百草枯的光催化降解实验表明,两种复合材料均具有较高的光催化活性.在365 nm紫外光辐照下,以H3PW12O40/MCM-41和H4 SiW12O40/MCM-41为催化剂催化反应14h后,百草枯(10 mg·L-1)的降解转化率分别达到92.0％和87.6％,反应符合一级化学动力学模型,半衰期分别为3.7和4.6h.
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