Bi/BiVO4@mSiO2三元异质结构光催化降解抗生素废水的性能及机理研究

In recent years, the problems of water pollution and ecological environment caused by antibiotics and their derivatives are more serious than before.The photocatalytic oxidation technology for the degradation of antibiotic wastewater has become one of the research fronts in the field of water pollution control, due to its low cost, energy conservation, environmental friendliness and so on. On the problems that the traditional photocatalytic materials with TiO2 as the brandmark perform low solar energy utilization and low efficiency for the removel of antibiotic wastewater, the project intends to introduce mesoporous SiO2 coating and load Bi metallic nanoparticles in situ on the surface of BiVO4 semiconductor crystals, in order to construct novel Bi/BiVO4@mSiO2 ternary heterostructured composite with large surface area, high solar energy utilization and high quantum efficiency. Their photocatalytic performance for the degradation of antibiotic wastewater will be investigated under visible light irradiation. This project will also systematically study the interfacial combination mechanism and synergistic effect between mesoporous SiO2 shell, Bi nanoparticles and BiVO4 crystal. The purpose aims at revealing the regulating effects of heterogeneous composite on the seperation efficiency of photogenerated electron and hole, the rate of interfacial charge transfer and the solar energy utilization. The distribution of active sites, the active species and their law of function will be studied. And the photocatalytic mechanism of the degradation of antibiotic wastewater over the heterogeneous compostie will also be proposed. It will provide a new idea for improving the photocatalytic efficiency of antibiotic wastewater removal and designing novel high-efficient visible-light responsive photocatalysts.

近年来抗生素及其衍生物所导致的水体污染和环境生态效应日趋严重。光催化氧化降解抗生素废水技术因其经济节能、环境友好等优点成为水污染治理前沿研究领域之一。本项目针对以二氧化钛为代表的传统光催化剂对太阳能利用率低以及去除抗生素废水效率偏低等关键问题，拟通过在窄禁带半导体BiVO4表面上引入介孔SiO2包覆层和原位负载金属Bi来构建高量子效率、大比表面积和高太阳能利用率的新型Bi/BiVO4@mSiO2三元异质复合光催化材料，考察其可见光下降解抗生素废水的能力。系统研究介孔SiO2壳层、金属Bi与BiVO4之间的界面复合机理及协同作用机制，揭示异质复合体系对光生电子-空穴的分离效率、界面电荷的转移速率和太阳能利用率的调控作用以及催化剂活性中心分布、活性物种的种类和微观作用规律。阐明异质复合光催化剂降解抗生素废水的机理。本研究为提高光催化去除抗生素废水效率和设计新型高效可见光光催化剂提供新思路。

本项目针对以二氧化钛为代表的传统光催化剂对太阳能利用率低以及去除环境污染物效率偏低等关键问题，选取钒酸铋（BiVO4）、铌酸钠（NaNbO3）等作为研究对象，通过在表面上引入氧化物/络合物或原位负载金属来构建高量子效率、大比表面积和高太阳能利用率的新型二元/三元异质复合光催化材料，考察其可见光下降解环境污染物的能力。主要研究工作及结果如下:（1）利用溶胶凝胶法制得的BiVO4纳米颗粒和商业Bi粉共同水热制备了Bi/BiVO4异质结构材料。初步研究结果表明当Bi粉质量分数为10%时，水热温度为180°C，保温时间为24小时，在可见光催化降解诺氟沙星时活性较好，5小时的降解率达到53%。（2）采用溶胶凝胶法和水热法并在不同酸介质下合成了BiVO4/TiO2光催化剂，重点考察了不同酸（醋酸、硝酸和硫酸）对催化剂晶型、形貌、比表面积和气相降解苯性能的影响，结果表明相对于其他腐蚀性较强的无机酸，醋酸的使用不但安全环保，而且使得制备出的光催化剂具有更优异的性能。（3）以单宁酸为多酚配体，常温下与钌离子（RuIII）配位进而在窄禁带半导体 BiVO4 表面快速组装形成钌-单宁酸（RuIII-TA）络合物壳层，同时利用单宁酸的络合和还原性质，一步合成在壳层中嵌入Pd纳米颗粒的BiVO4@RuIII-TA络合物核壳结构材料。可见光照射3小时后，纯BiVO4对RhB的降解率约为38％，而在相同的实验条件下，BiVO4@RuIII-TA和Pd/BiVO4@RuIII-TA核壳结构材料对RhB的降解率约为77.4％和91.6％，其活性是纯BiVO4的2倍和2.4倍。初步阐明RuIII-TA配位层、贵金属Pd对光催化材料活性的影响及作用机理。（4）通过在紫外光响应的半导体铌酸钠（NaNbO3）上负载Ru活性物种、与有色有机污染物相互作用等手段制备了NaNbO3/Ru负载型催化剂，拓展了复合材料的光谱响应范围至可见光区域。Ru负载量为0.5%的催化剂表现出最好的降解性能，并且在5轮的催化降解试验过程中没有出现明显的失活现象，从化学本质揭示了NaNbO3/Ru负载型催化剂能够高效催化降解水中微量RhB和Cr(VI)的原因。本研究为提高光催化去除环境污染物效率和设计新型高效可见光光催化剂提供新思路。