碳掺杂的磁性铁酸盐光芬顿催化氧化脱氮及反应机理研究

Ammonia nitrogen is one of primary pollutants in China, no technique can effectively remove ammonia from wastewaters to date. Solar energy is an inexhaustible supply of clean energy, so photo-catalytic degradation of ammonia using solar energy brings a promising route for the removal of ammonia from wastewaters. The item suggests that carbon materials such as graphene, graphene oxide, and activated carbon hybridize with metal ferrites to prepare carbon-doped metal ferrites as magnetic heterogeneous photo-Fenton catalysts for the removal of ammonia. The catalysts may be immobilized and recovered via extra magnetic field due to their magnetic properties, their response to solar spectrum will be extended to visible light zone due to the carbon material doping, and they will catalytically oxidize ammonia selectively to nitrogen gas via loading noble metals, realizing the thorough removal of ammonia from wastewaters. Further, the interaction of incident lights with carbon materials and the carbon-doped metal ferrites will be investigated via laser flash photolysis, photo-electrochemical methods, and electron paramagnetic resonance spectrometry. And moreover, the electron transfer mechanism involved in oxidization of ammonia to nitrogen gas will be studied via photoelectrochemical methods. It is believed that the removal of ammonia based on photo-Fenton oxidization using the carbon-doped metal ferrite catalysts is significant for the efficient utilization of solar energy and environmental protection, especially, elucidating the photo-catalytic principle of carbon-doped metal oxides.

氨氮是我国主要的污染源之一，迄今为止还没有一个行之有效的方法解决氨氮的污染问题。太阳能是一种取之不尽的清洁能源，利用太阳能光催化降解氨氮给污水脱氮带来了新希望。本课题利用石墨烯、氧化石墨烯、活性炭等碳材料掺杂铁酸盐，制备对可见光有光催化响应的磁性异相光芬顿催化剂。通过使用磁性材料实现催化剂的回收利用，通过碳材料的掺杂扩大催化剂对太阳光谱的响应范围，通过负载贵金属实施对氨氮的选择性催化氧化从而实现污水直接脱氮。在此基础上，我们拟从光与杂化材料之间的相互作用、光与碳材料之间的相互作用入手，通过电化学法、光电化学法等实验手段研究光与杂化材料的作用机理；进一步地结合电化学手段阐明杂化材料氧化氨氮的电子转移反应机理。我们相信，研究碳掺杂铁酸盐光芬顿氧化脱氮，不仅能为我国的环境保护事业和太阳能的有效利用作出贡献，而且也为揭示碳-金属氧化物杂化材料的光化学反应原理打下良好的科学基础。

氨氮现已成为我国主要的污染物之一。传统生物脱氮方法容易受温度、泥年、污染物成分的影响，从而不能稳定运行，降解不彻底，甚至不达标。因此需要研究开发高效、稳定、廉价的脱氮新工艺。太阳能是廉价、无二次污染的自然能源。因此，设计高效率、高催化活性、高稳定性并可循环使用的光催化剂，对于太阳能的利用和环境保护具有十分重要的意义。本项目设计合成了一系列的碳-铁酸盐杂化光催化剂：石墨烯-铁酸镍(G-NiFe2O4)、活性炭-铁酸镍(AC-NiFe2O4)、石墨烯-铁酸锰(G-MnFe2O4)、活性炭-铁酸锰(AC-MnFe2O4)、石墨烯-铁酸铋(G-BiFeO3)、活性炭-铁酸铋(AC-BiFeO3)和石墨烯-铁酸锌(G-ZnFe2O4)光催化剂。光催化研究表明，碳材料-铁酸盐杂化材料的光催化活性比相应铁酸盐的光催化活性几乎高一倍。这说明碳材料显著增强了铁酸盐的光催化效率。循环实验表明，该系列催化剂十分稳定、容易分离，并可重复循环使用。