Enhancing the adsorption of vapor-phase mercury chloride with an innovative composite sulfur-impregnated activated carbon

Mercury chloride (HgCl2) is the major mercury derivate emitted from municipal solid waste incinerators, which has high risk to the environment and human health. This study investigated the adsorption of vapor-phase HgCl2 with an innovative composite sulfurized activated carbon (AC), which was derived from the pyrolysis, activation, and sulfurization of waste tires. The composite sulfur-impregnation process impregnated activated carbon with aqueous-phase sodium sulfide (Na2S) and followed with vapor-phase elemental sulfur (S-0). Thermogravimetric analysis (TGA) was applied to investigate the adsorptive capacity of vapor-phase HgCl2 using the composite sulfurized AC. The operating parameters included the types of composite sulfurized AC, the adsorption temperature, and the influent HgCl2 concentration. Experimental results indicated that the sulfur-impregnation process could increase the sulfur content of the sulfurized AC, but decreased its specific surface area. This study further revealed that the composite sulfurized AC impregnated with aqueous-phase Na2S and followed with vapor-phase S-0 (Na2S + S-0 AC) had much higher saturated adsorptive capacity of HgCl2 than AC impregnated in the reverse sequence (S-0 + Na2S AC). A maximum saturated adsorptive capacity of HgCl2 up to 5236 mu g-HgCl2/g-C was observed for the composite Na2S + S-0 AC, which was approximately 2.00 and 3.17 times higher than those for the single Na2S and S-0 ACs, respectively. (C) 2012 Elsevier B.V. All rights reserved.