Wet process of gaseous Hg0 removal by Ag-AgIO3 modified BiOI photocatalyst
ZHOU Pu-yang1, ZHANG Xin-min1, ZHANG An-chao1, WANG Yi-chao1, SU Sheng2, LI Hai-xia1, XIANG Jun2
1. School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo 454003, China;
2. State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China
A series of Ag-AgIO3/BiOI photocatalysts were successfully synthesized by a coprecipitation-photoreduction method and characterized by X-ray diffraction (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS) and electron spin resonance (ESR). The effects of AgIO3 content, fluorescent lamp (FSL) irradiation, solution temperature, pH value, SO2 and NO on Hg0 removal were investigated in a photocatalytic reactor. In comparison to BiOI, Ag-AgIO3 photocatalyst exhibited an enhanced fluorescent-light-driven photocatalytic activity for Hg0 removal. When the loading of AgIO3 was 4wt.%, the removal efficiency of the Ag-AgIO3/BiOI photocatalyst was as high as 98%. Compared with NO, the inhibitory effect of SO2 on Hg0 removal efficiency became predominant. Due to the high dispersibility of Ag and AgIO3 on the surface of BiOI, the visible light absorption performance of Ag-AgIO3(4%)BiOI was significantly improved. The combination of fluorescent lamp irradiation and Ag-AgIO3/BiOI photocatalyst could produce a large number of active species. The mechanism showed that in the efficient mercury removal system of the Ag-AgIO3/BiOI photocatalyst, the superoxide radical (·O2-) was the most important active material, and the holes (h+) and hydroxyl radical (·OH) were the secondary factors.
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