Removal of elemental mercury by KI-impregnated clay

This study described the use of clay impregnated by KI in gas phase elemental mercury (Hg-o) removal in flue gas. The effects of KI loading, temperature, O-2, SO2 and H2O on Hg-o removal were investigated using a fixed bed reactor. The Hg-o removal efficiency of KI-clay with 3% KI loading could maintain at a high level (approximately 80 %) after 3 h. The KI-clay demonstrated to be a potential adsorbent for Hg-o removal when compared with activated carbon based adsorbent. O-2 was found to be an important factor in improving the Hg-o removal. O-2 was demonstrated to assist the transfer of KI to I-2 on the surface of KI-clay, which could react with Hg-o directly. NO and SO2 could slightly improve Hg-o removal, while H2O inhibited it greatly. The results indicated that after adsorption, most of the mercury escaped from the surface again. Some of the mercury may have been oxidized as it left the surface. The results demonstrated that the chemical reaction primarily occurred between KI and mercury on the surface of the KI-clay.