Selective removal of iron from aqueous solution using ion imprinted thiocyanato-functionalized silica gel sorbents

Abstract

We combined surface imprinting technique with sol-gel process for preparing a new iron(III)-imprinted thiocyanato-functionalized silica gel sorbent using 3-thiocyanatopropyltriethoxysilane as the functional monomer, and epichlorohydrin as the cross-linking agent for the selective removal of iron(III) from aqueous solution. The iron(III)-imprinted thiocyanato-functionalized silica gel was characterized by FT-IR spectra, SEM, and the static adsorptiondesorption method. Maximum binding capacity, optimum pH, and equilibrium binding time were found to be 20.31 mg·g−1, pH 4.2, and 20min, respectively. The relative selectivity coefficients of Fe(III)-imprinted thiocyanato-functionalized silica gel sorbents for Fe(III)/Ni(II), Fe(III)/Co(II), Fe(III)/Cd(II) and Fe(III)/Pb(II) were 11.8, 10.6, 8.2 and 9.1 times greater than the non-imprinted silica gel, respectively. The iron(III)-imprinted thiocyanato-functionalized silica gel sorbents could be used repeatedly without decreasing in their adsorption capacities significantly.