Silica gel modified with a novel sulfur-containing organic ligand (2-(benzo[d]thiazol-2-yl)-3,3-dimercapto acrylonitrile) for enhance Hg and Pb removal

Abstract

The induced selectivity of silica gel was carried out via modification with a synthesized organic ligand containing thiol (-SH) groups, 2-(benzo[d]thiazol-2-yl)-3,3-dimercapto acrylonitrile to selectively remove and preconcentrate of Hg and Pb ions from polluted water. The synthesis process primarily dealing with the impregnation of silica gel (SG) with a solution of the organic ligand in dimethyl sulfoxide (DMSO), followed by solvent evaporation and drying overnight at 100 °C. the obtained sample denoted as SG–L. The SG-L was characterized using several techniques including TGA, HNMR, mass spectroscopy, elemental analysis, SEM, EDX, and XPS. The removal selectivity and efficiency of SG–L for Hg and Pb ion removal from aqueous solution were evaluated in batch and fixed-bed column runs. The adsorption kinetics, thermodynamics, and effect of different experimental conditions, such as pH and temperature, on the adsorption process were also investigated. The obtained results indicate higher induced selectivity of SG–L toward Hg and Pb with the maximum adsorption capacities approximately 264–175 mg/g, respectively. The data also reflects the pseudo-second order endothermic nature of the adsorption process in a neutral pH range. The effluent history of column runs indicated the successive removal of mixed Hg and Pb from polluted water that lasts for 10,000 and 5,000 bed volumes (BVs) for both ions, respectively. The reusable nature of granulated SG-L along with high Hg and Pb removal capacity under the appearance of background ions implied that SG-L can be practically applied in the industrial settings.

Keywords

• Mercury removal
• Sulfur-containing ligands
• Silica gel