挥发性甲基硅氧烷在含锰石墨烯体系中的深度去除机理研究

Volatile methylsiloxanes (VMS) are considered emerging environmental contaminants that hinders utilization of biogas as an energy source. The development of green and efficient technology for VMS removal is highly desired. In this project, we propose to improve the removal efficiency of VMS by acidolysis with sulfuric acid through the cooperative effect between MnOx and GO/RxGO, and an effective MnOx-graphene-H2SO4 absorption system with low acid concentration will be developed. The adsorption efficiency of VMS can be improved through the synergistic effect between MnO2 and three-dimensional structure of graphene with separation free. The effect of the three-dimensional gel structure, facial adsorption and hydrophobicity of graphene on the adsorption performances such as capacity, selectivity and regeneration performance for VMS removal will also be investigated. A controlled assembly method for three-dimensional MnO2-RxGO aerogel, and a MnO2-RxGO based chemisorption-adsorption coupled system for VMS deep removal will be established. We also prioritize to explore the structure-activity relationship of three-dimensional nanostructure and the removal mechanism of VMS. This study will provide novel materials, methods and principles for biogas upgrading and VMS pollution control.

挥发性甲基硅氧烷（VMS）是一类新型环境污染物，并严重阻碍了生物气的能源化应用，目前还缺少绿色、高效的净化技术。本课题拟利用MnOx和GO/RxGO的协同作用提高硫酸酸解去除VMS的性能，发展高效、低酸浓度的氧化锰-石墨烯-硫酸三元化学吸收体系；利用MnO2和石墨烯形成的三维结构提高VMS的吸附性能，揭示三维凝胶结构、石墨烯的面吸附特性和疏水性对吸附量、吸附选择性及再生性能的影响机理，建立新型MnO2-RxGO三维复合气凝胶吸附体系及其可控组装方法；构建基于含锰石墨烯体系的化学吸收-吸附耦合系统，实现VMS的深度去除。重点揭示三维纳米结构的构效关系，阐明VMS去除机理。本研究将为解决生物气品质提升和VMS污染控制问题提供新材料、新方法和新原理，具有重要的科学意义和现实意义。

共存于生物气中的微量挥发性甲基硅氧烷（VMS）会严重阻碍生物气的能源化应用，需要选择性深度去除。本项目以VMS模拟生物气为研究对象，以研发绿色、高效的吸收与吸附净化原理和技术方法为目标，完成的主要研究工作包括：基于硫酸溶液酸解吸收净化VMS的原理，研究了硫酸浓度、氧化锰与氧化石墨烯共存、温度等因素对六甲基二硅氧烷(L2)和八甲基环四硅氧烷(D4)的去除作用影响；以工业级多层氧化石墨烯(IGGO)为原料，通过水热还原法和水热化学还原法合成还原氧化石墨烯气凝胶(rGOA)及MnxOy-rGOA复合吸附剂，研究了典型VMS在rGOA基材料填充床中的吸附净化特征与作用机制。研究结果表明，室温及70% H2SO4对L2的去除率为84%，加入0.2 g·L-1氧化锰和氧化石墨烯使L2的去除率小幅提高到92%。rGOA-x对L2的吸附性能随水热处理温度的升高而增大，rGOA-200 对L2显示出最优的吸附性能， QB 为 24.7 mg·g-1。水热还原法合成的rGOA对L2的吸附性能随胺分子pKa值的减小而提高， U-rGOA的吸附性能最优，其QB 为112.4 mg·g−1。研究揭示出QB 与SBET 和Vmicro具有显著的相关性，硅氧烷的吸附遵循微孔充填和疏水作用机制。氧化锰复合能改善rGOA的织构性质，提高硅氧烷吸附性能。实验证明rGOA容易热解吸再生，可以多次重复使用。项目研究中还发现了固体负载硫酸/磺酸可有效吸附转化苯系物VOCs的新功能。本研究结果可为解决生物气品质提升和VMS污染控制问题提供材料和技术支持。