现有燃煤电厂汞污染控制技术未能实现零价汞排放的集中控制，而是将零价汞转化成毒性更高的二价汞，最终转移到飞灰或脱硫石膏中，极易产生二次污染。我们课题组提出了利用可循环使用的磁性吸附剂协同湿式电除尘器回收燃煤烟气中的零价汞加以集中控制的新思路，并试图将硫化磁赤铁矿与湿式电除尘器相结合集中控制燃煤烟气汞污染。但硫化磁赤铁矿的热稳定性较差，在热脱附回收零价汞的过程中易发生相变而失去磁性，不利于循环使用。为此，本项目拟通过多酸嫁接对硫化磁赤铁矿进行改性：一方面通过调控多酸与磁赤铁矿的界面效应抑制磁赤铁矿相变而提高其热稳定性，进而提高其磁性；另一方面通过控制多酸嫁接磁赤铁矿表面的硫化效应而提高其表面活性硫物种的含量，进而提高其零价汞吸附能力。本项目将开发出能协同湿式电除尘器回收燃煤烟气中零价汞的高效并可循环使用的磁性吸附剂，为推动我国燃煤电厂汞污染控制从形态调控向集中控制的转型升级提供重要技术支撑。

The existing mercury pollution control technologies in coal-fired power plants fail to achieve the centralized control of elemental mercury emission, but it converts elemental mercury into divalent mercury with a higher toxicity, which is eventually transferred into fly ash or desulfurized gypsum. However, it is easy to produce secondary pollution. Our research group has proposed a new idea of using a recyclable magnetic sorbent for recovering elemental mercury to achieve the centralized control of elemental mercury from coal-fired flue gas as a co-benefit of wet electrostatic precipitators. In our previous study, sulfurated maghemite was developed to recover elemental mercury from coal-fired flue gas as a co-benefit of wet electrostatic precipitators. However, the thermal stability of sulfurated maghemite was poor, which made it prone to phase transition and loss of magnetism during the process of recovering elemental mercury through the thermal desorption. This was not conducive to recovering the sorbent for recycling. In this project, sulfurated maghemite will be modified with polyoxometalates grafting. On the one hand, the phase transition of sulfurated maghemite will be restrained through regulating the interface effect of polyoxometalates and maghemite, which will significantly improve its thermal stability and magnetism. On the other hand, the amount of active sulfur species on sulfurated maghemite will also be notably increased by controlling the sulfuration effect on polyoxometalates grafted maghemite, which will remarkably improve its performance for elemental mercury capture at low temperatures. In summary, this project will develop high-performance and recyclable magnetic sorbents for recovering elemental mercury from coal-fired flue gas as a co-benefit of wet electrostatic precipitators, which provides an important technology support for promoting the transformation and upgrading of mercury pollution control in China’s coal-fired power plants from valence state regulation to the centralized control.