Cr(VI) sorption by intact and dehydrated Candida utilis cells in the presence of other metals

This study examined the Cr(VI), Cu(II), Zn(II), Cd(II), Pb(II) sorption by intact and dehydrated Candida utilis cells. The anion [Cr2O7](2-) and cation Me2+ sorption kinetics was investigated in both single- and dual-metal situations. Uptake of chromate anions occurred much more slowly singularly than with metal cations. A combination of Pb or Cu and chromate anions gave a synergistic effect for Cr(VI) sorption, but not Cd and Zn, which inhibited Cr(VI) sorption by dehydrated cells. The use of alcian blue to occupy maximum vacant adsorption sites on the cell surface unexpectedly did not influence further adsorption of Me. Metal uptake by C utilis was 7 mg (135 muM) Cr, 23 mg (362 muM) Cu, 39 mg (188 muM) Pb, 19 mg (170 muM) Cd, 28 mg (428 muM) Zn gdw(-1). Estimations of the number and area of metal ions occupying the cell surface was made and data obtained indicated that area of sorbed Cr(VI), Cd(II), Cu(II), Pb(II) occupied the single cell did not cover all the surface, whereas Zn(II) covered up to 168%. (C) 2002 Elsevier Science Ltd. All rights reserved.