POLYETHYLENEIMINE ADDUCT OF POLY(VINYL BENZALDEHYDE) - A HIGHLY SELECTIVE SORBENT FOR IRON(III)

Polyethyleneimine of molecular weight 50,000-60,000 has been reacted with poly(vinyl benzaldehyde), the latter being derived from crosslinked chloromethylated polystyrene by the Sommelet reaction. The resulting polymeric adduct shows highly preferential sorption for Fe(III) over Cu(II), Ni(II), Co(II), Fe(II), Zn(II) and Mn(II) irrespective of the relative concentrations of the species in aqueous solution, while in the absence of Fe(III) copper is sorbed in preference to the other metal ions. Though both Cu(II) and Fe(III) sorptions are markedly reduced by lower pH, Fe(III) shows substantial sorption even in highly acidic (pH < 2) solutions. The Fe(III) sorption rate is diffusion controlled and shows good agreement with a finite-bath shell-core model for reacted-layer-diffusion control, yielding a value of 2.5 X 10(-7) cm2/s for the product of distribution coefficient and diffusivity. The sorbed Fe(III) is readily stripped by 2 N HCl or H2SO4.