Economical and environmentally friendly synthesis of strong cation-exchange resins from macroporous styrene–divinylbenzene copolymers

Abstract

In the process of strong acid resin synthesis, the process step of acetone washing is meant to extract diluent and homopolymer/oligomers from styrene–divinylbenzene base copolymer. Acetone accounts for ~80 % of the cost of the chemicals involved in the synthesis of the copolymer. Acetone also causes environmental pollution and poses health risks to workers. This study demonstrates that the acetone washing can be eliminated in the case of a broad range of solvents commonly employed as diluents in the synthesis of copolymers. Specifically, hydrocarbons such as petroleum ether, isooctane, n-heptane, xylene and toluene can be extracted based on steam distillation phenomena during the curing of the copolymer; esters such as diethylphthalate and butyl stearate are sulfonated and/or hydrolyzed and washed with water; alcohols such as 1-hexanol, tert-amylalcohol, benzoyl alcohol, and ketones such as cyclohexanone are partially soluble in water and can be washed with hot water. The residual homopolymers/oligomers are sulfonated and washed with water. Residual esters have no negative effect and traces of residual alcohols or ketones either have no negative effect or they significantly increase the sulfonation of the copolymer compared to that of acetone-washed copolymers.