Selective adsorption of Pb(II) by a silica gel-immobilized Schiff base

A novel silica gel-based absorbent SG-GA, capable of selective adsorption of Pb(II) from an aqueous solution containing mixed metal ions of Cr(VI) and Cu(II), was prepared by grafting of a Schiff base glutaraldehyde (GA) ligand onto the surface of a modified silica gel. The functionalized silica gels were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, and porous structure analysis. The effect of pH, contact time, the concentration of Cr(VI) and Cu(II), and initial Pb(II) concentration parameters on the adsorption of Pb(II) ions were investigated. The effective pH range for selective Pb(II) adsorption was in the region 3 similar to 8. The adsorption study showed that SG-GA had good adsorption efficiency for Pb(II), and the maximum adsorption capacity was 19.96 mg g(-1). The adsorption kinetics of Pb(II) followed the pseudo-second-order kinetic models and the adsorption isotherms fitted well by Langmuir models, these results implied that the absorption selectivity may be tuned by modifying the structural conformation for the sites of metal ion binding through complexion. This study provides interesting material for selectively and effectively remove Pb(II) from water effluents containing mixed metal salts.