Removal of Cr(VI) by solvent impregnated resins (SIR) containing aliquat 336

Solvent impregnated resins (SIR) have been prepared by a wet-impregnation technique using two different polymer matrices, Diaion HP-20 and HP-2MG. Diaion HP-20 possesses a hydrophobic styrene-divinylbenzene polymeric structure whereas HP-2MG is a hydrophilic methacrylic based polymer. Aliquat 336 was employed as the extractant and acetone as the solvent for impregnation. Batch sorption studies have shown that solvent impregnated resins containing Aliquat 336 can be effectively used for the removal of hexavalent chromium from aqueous solutions. The Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. A kinetic study has been performed for SIR at two different concentrations of Cr(VI) (2 X 10(-4) and 4 X 10(-4) M). A finite-bath diffusion-control model with changing bulk concentration was used for sorption of Cr(VI) by SIR. Increasing the impregnation ratio from 0.5 to 1.0 (g Aliquat 336/g polymer adsorbent) increased the breakthrough capacity in a column-mode sorption study. The Cr(VI) bound by the SIR has been quantitatively desorbed using 0.1 M NaOH-0.1 M NaCl mixture. (C) 2002 Elsevier Science B.V. All rights reserved.