Single and Dual Adsorption of Vapor-Phase Hg^0 and/or HgCl2 by Innovative Composite Activated Carbons Impregnated with both S^0 and Na2S

10.4209/aaqr.2013.03.0072

Iau-Ren Ie；Hua-Zhen Shen；Chung-Shin Yuan；Chung-Hsuang Hung；Wei-Hsiang Chen；Yi-Hsiu Jen

Thermogravimetric analysis (TGA) ； Powdered activated carbons (PACs) ； Composite sulfur impregnation ； Single and dual adsorption of Hg^0 and/or HgCl2 ； Saturated adsorptive capacity

Aerosol and Air Quality Research

14卷1期（2014 / 02 / 01）

376 - 385

英文

This study investigated the single and dual adsorption of vapor-phase Hg^0 and/or HgCl2 using an innovative composite sulfurized activated carbon prepared by combining two sulfur impregnation methods. Thermogravimetric analysis (TGA) technology was applied to determine the saturated adsorptive capacity of Hg^0 and/or HgCl2. Experimental results indicated that the saturated adsorptive capacity of Hg^0 and/or HgCl2 increased with both the concentration and adsorption temperature. This suggests that the adsorption of Hg^0 and/or HgCl2 on the composite sulfurized PACs follows a process of chemisorptions, with adsorption being favored at elevated temperatures. Additionally, when the adsorption occurred at 200-300°C, the saturated adsorptive capacity of Hg^0 on the composite sulfurized PACs was higher than that of HgCl2. Using coal-fired power plants as an example, the saturated adsorptive capacity of single Hg^0 or HgCl2 was always higher than that of dual Hg^0 and HgCl2 when the molar ratio of influent HgCl2 to Hg^0 was 5:5. In addition, the breakthrough time became shorter and the saturated adsorptive capacity decreased significantly, suggesting that competitive adsorption of Hg^0 and HgCl2 occurred on the activated sites. Using municipal solid waste incinerators (MSWIs) as an example, where the molar ratio of influent HgCl2 to Hg^0 was 6:4, the saturated adsorptive capacity of HgCl2 and/or Hg^0 at the coal-fired power plants was significantly lower than that of the MSWIs at the adsorption temperatures of 150, 200, and 300°C. This shows that HgCl2 is a more competitive adsorbate than Hg^0, which could tentatively be replaced by HgCl2 on the adsorptive sites. The experimental results indicate that the molar ratio of influent HgCl2 to Hg^0 affected the viscosity of these two mercury species, as well as the saturated adsorptive capacity of dual Hg^0 and HgCl2. The saturated adsorptive capacities of Hg^0/HgCl2 found in this study were approximately 2.9-61.4 and 8.4-251.1 times higher than those in previous studies.