Facile synthesis of ternary Ag/AgBr-Ag2CO3 hybrids with enhanced photocatalytic removal of elemental mercury driven by visible light

A novel technique for photocatalytic removal of elemental mercury (Hg-0) using visible-light-driven Ag/AgBr-Ag2CO3 hybrids was proposed. The ternary Ag/AgBr-Ag2CO3 hybrids were synthesized by a simple modified co-precipitation method and characterized by N-2 adsorption-desorption, scanning electron microscope (SEM), X-ray diffraction (XRD), UV-vis diffused reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) techniques. The effects of AgBr content, fluorescent lamp (FSL) irradiation, solution temperature, SO2 and NO on Hg-0 removal were investigated in detail. Furthermore, a possible reaction mechanism for higher Hg-0 removal was proposed, and the simultaneous removal of Hg-0, SO2 and NO was studied. The results showed that a high efficiency of Hg removal was obtained by using Ag/AgBr-Ag2CO3 hybrids under fluorescent lamp irradiation. The AgBr content, FSL irradiation, solution temperature, and SO2 all exhibited significant effects on Hg removal, while NO had slight effect on Hg-0 removal. The addition of Ca(OH)(2) demonstrated a little impact on Hg removal and could significantly improve the SO2-resistance performance of Ag/AgBr(0.7)-Ag2CO3 hybrid. The characterization results exhibited that hydroxyl radical ((OH)-O-center dot), superoxide radical (O-center dot(2)-, hole (hi), and Br-0, were reactive species responsible for removing Hg-0, and the h(+) played a key role in Hg removal. (C) 2016 Elsevier B.V. All rights reserved.