Simultaneous aqueous Hg(II) adsorption and gaseous Hg 0 re-emission inhibition from SFGD wastewater by using Cu and S co-impregnated activated carbon

• Published in: Chemosphere (Oxford) Vol. 263; p. 127966
• Main Authors: Hsu, Che-Jung, Xiao, Yan-Ze, Hsi, Hsing-Cheng
• Format: Journal Article
• Language: English
• Published: England 01.01.2021
• Subjects: Adsorption; Air Pollutants - analysis; Charcoal; Coal; Mercury - analysis; Power Plants; Seawater; Waste Water; Coal combustion; Seawater flue gas desulfurization; Adsorption; Mercury; Activated carbon
• ISSN: 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127966

Seawater flue gas desulfurization (SFGD) has shown great effectiveness in the controlling of sulfur dioxide (SO ) emission and the removing of mercury (Hg) from flue gases of coal-fired power plants. Some problems pertaining to SFGD for Hg control, however, remain to be solved: (1) environmental impact from the discharge of Hg-containing seawater to the ocean, and (2) re-emission of gaseous Hg from the aeration tank to the atmosphere. This study synthesizes the copper/sulfur co-impregnated activated carbon (Cu-S-AC) to simultaneously capture aqueous Hg(II) and inhibit gaseous Hg re-emission from actual SFGD wastewater. Cu-S-AC exhibited greater Hg(II) adsorption than both raw activated carbon (AC) and sulfur-impregnated activated carbon (S-AC) at an initial Hg(II) concentration of higher than 8000 ng/L. The Hg(II) adsorption of Cu-S-AC was slightly greater at pH 7 and 8 than that under acidic conditions. The Hg(II) adsorption was well-fitted with both linear and Freundlich isotherms. The results of thermodynamic analyses veiled the endothermic and spontaneous adsorption of Hg(II) on Cu-S-AC. In addition, the pseudo-second-order equation provided the best correlation coefficient for the Hg(II) adsorption on Cu-S-AC. Notably, the increases of pH and temperature increased the Hg re-emission. Nevertheless, Cu-S-AC addition significantly inhibited the Hg re-emission (92%) from SFGD wastewater.