Anion exchangers with alkyl substituted guanidyl groups Gold sorption and Cu(II) coordination

Two methods of introducing guanidyl groups into polymer matrix were investi gated in this work: the reaction of cyanamide (alkyl substituted cyanamides ) and carbodiimides with amino groups in modified polystyrene. The new anio n exchangers (AEG) with alkyl substituted guanidyl groups contain 1.5-2.3 m mol/g of ligands and exhibit high selectivity towards Au(CN)(2)(-) anions. From the solution containing 2 ppm of gold the sorption is as high as 30 mg /g. Furthermore, AEG reveal high affinity towards tetrachloroaurate anions. The log K in diluted solution is about 5. The values of gold sorption as d icyanoaurate or tetrachloroaurate anions on AEG with alkyl substituted hydr ogen atoms in guanidyl groups is two-four times higher than sorption on ani on exchangers synthesized previously by exchange of chlorine with guanidine or aminoguanidine. The EPR studies of Cu(II)-loaded AEG were undertaken to correlate the structural properties of the formed complexes with the natur e of the ligands, the ligand concentration, water regain of the resins and pH. (C) 2001 Elsevier Science B.V. All rights reserved.