A series of studies on the performance of Hg0 removal from simulated flue gas were carried out in a wet Hg0 bubbling reactor using a visible-light-responsive Ag/AgCl photocatalyst prepared by a precipitation-photoreduction method. The effects of SO2, NO, and reaction temperature were also investigated in detail. The properties of fresh and used photocatalysts were characterized by N2 adsorption/desorption, scanning electron microscope and energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) techniques. The results showed that compared with the Hg0 removal efficiencies of only visible light irradiation and only Ag/AgCl, Hg0 removal efficiency was greatly enhanced when visible light and Ag/AgCl were employed simultaneously. Due to large amounts of reactive species consumption, the presences of SO2 and NO would inhibit the performance of Hg0 removal. The activity of Hg0 removal could be restored to their initial values when SO2 and NO were turned off. The reactive species, such as hydroxyl radicals (⋅OH), superoxide radicals (⋅O2−), were produced in the Ag/AgCl solution under visible light. The⋅OH, holes (h+), and Cl2, were reactive species responsible for removing Hg0, and in particular the⋅O2– played a key role in Hg0 removal.%采用沉淀−光还原法制备了Ag/AgCl可见光催化剂,在湿法脱汞装置上考察了该光催化剂的Hg0脱除特性及SO2、NO和溶液温度等对脱汞性能的影响.利用N2吸附/脱附、扫描电子显微镜及X−射线能量色散谱(SEM-EDS)、X−射线衍射(XRD)、紫外−可见漫反射光谱(DRS)、X−射线光电子能谱(XPS)和电子自旋共振(ESR)技术对新鲜和使用后的光催化剂进行性质表征.结果表明,与单独可见光辐照和单独使用Ag/AgCl相比,Ag/AgCl与荧光灯联合使用的Hg0脱除效率大幅提高.SO2和NO的添加会抑制Ag/AgCl光催化剂对Hg0的脱除；停止通入SO2和NO后,Hg0脱除效率可快速恢复.可见光辐照下,Ag/AgCl光催化剂产生了强氧化性的羟基自由基(⋅OH)和超氧自由基(⋅O2–).各活性物种中,⋅O2–在Ag/AgCl光催化剂的高效脱汞过程中起关键作用,而⋅OH、空穴(h+)和Cl2为次要作用.
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