Mercury removal from water using activated carbons derived from organic sewage sludge

Various types of activated carbons were developed from organic sewage sludge (SS) using H2SO4, H3PO4 and ZnCl2 as chemical activation reagents, and the removal of Hg(II) from aqueous solution by these carbons was effectively demonstrated. The quality of the activated carbons was dramatically improved owing to chemical activation. ZnCl2 activated carbon had the highest capability for Hg(II) adsorption, followed by H3PO4 and H2SO4 activated carbons. The adsorption was greatly affected by Hg(II) concentration, solution pH and carbon dosage, and followed Lagergren first order rate equation and Freundlich isotherm model. Desorption results indicated that around 60% to 80% of the adsorbed Hg(II) could be recovered from the carbons to 0.1 M HNO3 solution by sonication treatment. Accordingly, it is believed that the activated carbons developed in this study are effective and practical for utilization in industrial wastewater treatment for mercury removal.