The chemical composition and structure of copolymers determines modificatio
n degree, concentration of Ligands, their accessibility and hence capacity
and selectivity of chelating resins. Ln order to investigate all such influ
ences, a new series of copolymers have been obtained: one with increased po
larity and hydrophilicity of polymer surface has been synthesized from viny
l benzyl chloride (VBC), methyl methacrylate (MM) and divinylbenzene (DVB)
mixture, another one with toluene and hexadecane as inert diluents. As was
expected copolymers synthesized in the presence of hexadecane, which is the
rmodynamically poor for the mixture of monomers, are porous with small pore
s (less than 1.8 nm radius) and with macropores (radius bigger than 17 nm).
After modification with aminoguanidine bicarbonate, resins with the Ligand
concentration in the range 1-2 mmol/g are more hydrophilic but porosity de
creases due to the elasticity of networks. The copolymers and resins obtain
ed in the presence of toluene have a gel expanded structure. The ability of
resins to remove dicyanoaurate complexes has been tested under the followi
ng conditions: an excess of potassium cyanide, 50 mg/l of dicyanoaurate con
centration and ratio of aminoguanidine ligands to gold complexes 7.7:1. Und
er these conditions the sorption for the concentration of ligands of 1.2 mm
ol/g was about 23 mg/g and for 2.0 mmol/g it was 30 mg/g. Sorption of gold
increases with increased ligand content, Sorption of gold at pH 7 is higher
than at pH 9.5 and at 13.5 comparable to that at pH 9.5. Lowering dicyanoa
urate concentration to 5 mg/l decreases the sorption of gold, but when the
Ligand to dicyanoaurate anions ratio is 1.1:1 the sorption reaches 30 mg of
gold/g, which corresponds to a distribution coefficient of 6900. However,
better sorption at low ligand to dicyanoaurate ratio is accompanied by much
lower extraction degree and distribution coefficient. (C) 1999 Elsevier Sc
ience B.V. All rights reserved.