Adsorption of gaseous elemental mercury with activated carbon impregnated with ferric chloride

Abstract

Fe-based modified activated carbon prepared by impregnation was used for adsorbents in Hg⁰ purification. The influence of carriers, active components, FeCl₃ solution concentration and calcination temperature, were investigated for Hg⁰ adsorption purification. The effects of the preparation conditions on the adsorbent were characterized by N₂ adsorption–desorption isotherms, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and (FTIR). The samples modified with FeCl₃ showed an obvious performance for Hg⁰ removal, because the chlorine in metal chlorides acts as an oxidant that promotes the conversion of elemental mercury (Hg⁰) into its oxidized form (Hg²⁺). The mechanisms of mercury adsorption onto the Cl-impregnated activated carbon were proposed. The optimal conditions for adsorptive purification are an Fe³⁺ concentration of 0.15 mol L⁻¹, calcination temperature of 300 °C at an adsorption temperature of 40 °C and carrier gas flow rate of 300 mL min⁻¹.