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Effective removal of inorganic mercury and methylmercury from aqueous solution using novel thiol-functionalized graphene oxide/Fe-Mn composite

Huang, Yao, Gong, Yanyan, Tang, Jingchun, Xia, Siyu
Journal of hazardous materials 2019 v.366 pp. 130-139
active sites, adsorbents, adsorption, antimony, aqueous solutions, binding capacity, cadmium, copper, electrolytes, graphene, groundwater, humic acids, lead, ligands, mercury, methylmercury compounds, models, nickel, pH, polymers, remediation, sorption isotherms, surface water, thiourea, viability, zinc
A novel thiol-functionalized graphene oxide/Fe-Mn (SGO/Fe-Mn) was investigated for aqueous Hg2+ and CH3Hg+ removal. Mercury were removed mainly through ligand exchange and surface complexation with surface active sites (i.e., −SH, OH, OCO, CC, SiO, and ππ bond). SH had the strongest binding ability with mercury, forming sulfur-containing organic matter or polymers with Hg2+, and sulfur-containing organometallic compounds or thiolate-like species with CH3Hg+. The BET sorption isotherm model well simulated the sorption isotherm data of Hg2+ (R2=0.995, qm=233.17 mg/g) and CH3Hg+ (R2=0.997, qm=36.69 mg/g), indicating a multilayer adsorption process. The mercury uptake was promoted with the increase of 3-MPTS content, adsorbent dosage, and pH (<5.5), whereas the uptake was inhibited by high pH (>5.5) and high concentrations of humic acid and electrolytes. SGO/Fe-Mn demonstrated high mercury uptake in simulated surface water/groundwater and in the presence of Pb, Cu, Ni, Sb, Cd and Zn. The mercury-laden SGO/Fe-Mn can be successfully regenerated and reused for three times with 98.1% and 67.0% of original Hg2+ and CH3Hg+ sorption capacity when 5% thiourea + 2 M KI was used as the desorbing agent. This study demonstrates potential and viability of SGO/Fe-Mn for mercury remediation.