SiO2/BiOBr光催化材料制备及其对含油废水的处理

Preparation of SiO2/BiOBr photocatalytic materials and treatment of oily wastewater

近几年来,水体中油污污染问题已引起广泛关注。许多研究尝试利用光催化材料催化降解含油废水,但催化条件大多仍局限于紫外光照。为解决这一问题,本研究将SiO2作为催化剂载体,采用共沉淀法制备出能在可见光下使用的SiO2/BiOBr复合材料。该材料经XRD、XPS、DRS、BET等测试分析后发现,BiOBr可负载于SiO2的片层表面,同时可有效增大其比表面积,提高吸附性能。并且将制备条件优化后表明,当n(Bi)∶n(Si)=1∶1时,该材料的比表面积为83.53m^2/g,禁带宽度(Eg)为2.79eV,复合效果最佳。使用该复合材料对不同类型油进行催化反应后,机油、柴油、食用油的去除率分别可达25%、60%、93%。本文详细分析了该材料柴油的光降解机理,发现·O2^-是最为主要的活性基团。

In recent years, oil pollution in water has caused wide concerns. Many studies have attempted to catalyze the degradation of oily wastewater by photocatalytic materials, but most techniques are still limited to ultraviolet light. In order to solve this problem, SiO2/BiOBr composites which can be used under visible light were prepared by coprecipitation method using SiO2 as the catalyst carrier. The material was characterized by XRD, XPS, DRS, BET and so on. It was found that BiOBr can be supported on the surface of SiO2, and it can effectively increase the specific surface area of SiO2, and thus can improve the adsorption performance. With n(Bi)∶n(Si)=1∶1, the specific surface area and the forbidden band width (Eg) of the material was 83.53m^2/g and 2.79eV respectively, resulting in the best performance. When the composite material was used to catalyze different types of oily wastewater, the removal rates of engine oil, diesel oil and edible oil were up to 25%, 60% and 93%, respectively. Further, the photodegradation mechanism of diesel oil was analyzed in detail, and it was found that ·O2^- was the most active group.