Abstract:

Biochar derived from biomass pyrolysis have been widely used in chemical, material, energy and environmental fields due to their developed pore structure, high specific surface area and easy electron transfer properties. At present, owing to the massive increase of organic pollutants in water bodies, the potential safety hazards to the human body and environment cannot be ignored. Therefore, it is important to use green and efficient photocatalysts for the treatment of organic pollutant wastewater. This paper reviews the latest research progress on biochar-based photocatalysts prepared by different synthetic methods for the disposal of various organic pollutants in wastewater. Firstly, different preparation methods of biochar carriers were compared and analyzed, revealing the characteristics of pyrolysis, hydrothermal carbonization, and baking, and providing ideas for the selection of the best preparation method of biochar. Biochar-based composites can effectively avoid the agglomeration phenomenon of nano-photocatalytic materials and promote the dispersion of photocatalysts on the surface of biochar. Therefore, this review also introduces the methods of preparing photocatalysts such as the sol-gel method, hydrolysis method, ultrasonic method, and thermal polycondensation, and describes the influencing mechanism of different preparation conditions for the activity of photocatalytic degradation of organic pollutants. On this basis, this article focuses on the application and effectiveness of biochar carriers and biochar-based composites for the removal of typical organic pollutants (methyl orange, gemifioxacin, rhodamine B, sulfamethoxazole, etc.) from wastewater, and summarizes the reaction mechanism into three steps: pollutant adsorption, photoexcited electron-hole and pollutant catalytic degradation. Meanwhile, biochar-based photocatalytic materials can increase the contact area with pollutants and enhance the mass transfer process of pollutants, thus significantly improving the catalytic activity of photocatalysts. Finally, the research highlights and offers prospects from the perspective of being green, clean and sustainable, and it is hoped that this review will guide future development of new biochar-based catalysts and research in photocatalysis.

Key words: biochar, photocatalysis, biomass, organic pollutants, photocatalysts, reaction mechanism

摘要：

基于生物质热解得到生物炭材料具有发达的孔隙结构、高比表面积和电子传递效率高等性质，已经被广泛应用于化工、材料、能源、环境等研究领域。目前，由于水体中各种有机污染物的大范围增加，对人体和环境造成的安全隐患不容忽视。因此，利用绿色高效的光催化剂对有机物污染物废水进行高效处置具有重要意义。该文针对不同合成方法制备的生物炭基光催化剂对废水中各种有机污染物处置的最新研究进展进行了综述。首先对生物炭载体的不同制备方法进行了对比与分析，为后续生物炭最佳制备方式的选择提供了思路。生物炭基载体能够有效避免纳米光催化材料的团聚现象，促进光催化剂在生物炭表面的分散。因此，该文还介绍了溶胶-凝胶法、水解法、超声法和热缩聚等光催化剂的制备方法，阐述了不同制备条件对光催化降解有机污染物活性的影响机制。在此基础上，重点综述了生物炭基复合材料在去除废水中典型有机污染物（甲基橙、吉米沙星、罗丹明B、磺胺甲恶唑等）方面的应用与有效性，并且将光催化剂的反应机理总结为污染物吸附、光激发电子-空穴以及污染物催化降解3个步骤。同时，生物炭基光催化材料能够增加与污染物的接触面积与提高污染物的传质过程，从而显著提高光催化剂的催化活性。最后，从绿色、清洁、可持续的角度展望了该领域的研究重点及前景，希望该综述能为新型生物炭基催化剂的研发及其在光催化研究方面提供指导性建议。

关键词: 生物炭, 光催化, 生物质, 有机污染物, 光催化剂, 反应机理