New selective resins with guanidyl groups

Abstract

Conditions of reaction between nitrile groups of acrylonitrile/vinyl acetate/divinylbenzene (ANNA/DVB) copolymer and aminoguanidine bicarbonate (AGB) leading to N-substituted amides have been optimized. It has been found that the highest concentration of amino groups can be achieved carrying out aminolysis in the presence of a butanol/water mixture as solvent. Resin obtained under such conditions has 2.20 mmol/g of amino groups and 2.40 g/g water regain. Modified resins display a smaller average pore diameter (5.6 nm) than starting ANNA/DVB copolymer (11.2 nm), indicating that the pore surface is covered with amide gel. When water is used as solvent in aminolysis reaction the degree of modification is smaller and the structure of the resulting resin is similar to that of the starting copolymer. Sorption of Cu(111) on obtained resins is high and proportional to amino group concentration, whereas sorption of Au(CN)2 under alkaline conditions in the presence of excess KCN depends on the structure of the acrylic resin but not on amino group content. Resins which have been modified with AGB in the presence of a butanol/water mixture are 9-times (49.3 mg/g of dry resin) more effective in gold cyanide removal than those modified in water. Other polymers such as: methacrylic acid/trimethylolpropane trimethacrylate (TMPMA), glycidyl methacrylate/TMPMA, glycidyl methacrylate/trimethylolpropane triacrylate and vinylbenzylchloride/styrene/divinylbenzene have been investigated as matrices for aminoguanidine ligands. In the case of the latter polymer, containing 2 wt% of crosslinking agent, sorption of gold cyanide is 55.0 mg/g.