Photocatalytic activity and characterization of AgCl/Ag composite for Hg0 removal under fluorescent light irradiation

Abstract

A AgCl/Ag composite was synthesized via a facile precipitation method and applied to the photocatalytic oxidation removal of elemental mercury (Hg0) in a wet bubbling reactor under fluorescent light irradiation. The fresh photocatalyst and the used materials were characterized by N2 physisorption, X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and electron spin resonance. The results showed that the AgCl/Ag photocatalyst and fluorescent light have a great synergistic effect on Hg0 removal. A higher solution temperature was not favorable for Hg0 removal. The presence of lower concentrations of SO2 or NO showed little effect on Hg0 removal, whereas the inhibition of SO2 or NO on Hg0 removal became more serious with the SO2 or NO concentration increasing. Some amounts of Ag0 were produced onto the AgCl/Ag surface during the process of Hg0 removal in the absence and presence of SO2 or NO. The trapping experiments confirmed that •O2− was the primary reactive species in the photocatalytic process.