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  • 1 Indira Gandhi Centre for Atomic Research Fuel Chemistry Division Kalpakkam 603 102 India
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Mesoporous silica (MCM-41) with d (100) interplanar distance of 38 Å was prepared by a room temperature process through low surfactant templation technique. The surface of MCM-41 was functionalized with dithiocarbamate (dtc) ligand, named as MCM-41-dtc and this was characterized by X-ray diffraction, BET surface area, particle size analysis, 29Si MAS NMR spectra and sulphur analysis. The sorption of mercury from 0.1M HCl solution by MCM-41-dtc was studied as a function of pH, [Hg2+], time and temperature. The sorption data obtained at various initial concentrations of mercury were fitted into Langmuir adsorption model. Mercury speciation in solution and the sorption capacity measurements indicated possible formation of a 1 : 1 square planar complex in the solid phase. A very rapid sorption of mercury was observed in the initial stages of equilibration, which can be attributed to the large surface area, wide porosity and fine particle size of MCM-41-dtc, facilitating facile accessibility of mercury into the inner pores of the sorbent. The enthalpy change accompanied by the sorption of mercury was found to decrease from 83.7 to 6.2 kJ/mol, when the initial concentration of mercury was increased from 5.10-4M to 1.5.10-3M.