A New Sulfonic Acid Cation-Exchange Resin Based on Polyvinyl Chloride and Its Evaluation in Water Softening

A sulfur-containing polymer was prepared by the reaction of granulated polyvinyl chloride with sulfur. Oxidation of this polymer with nitric acid led to the formation of a sulfonic acid cation-exchange resin. The presence of the sulfo group in the resin was proved by IR spectroscopy, and the cation-exchange properties were confirmed by determining the static exchange capacity. The morphology of the cation-exchange resin obtained was examined by scanning electron microscopy. The resin is heat-resistant at 423 K, and its resistance to strong oxidants such as perchloric and nitric acids and to strong bases is on the level of 80–95%. The kinetics of sorption of Са2+ and Мg2+ ions from aqueous solutions onto the synthesized resin was studied in batch experiments, and the sorption equilibrium constants were determined. The capacity of the cation-exchange resin prepared for Ca2+ and Mg2+ ions remained unchanged after five sorption–desorption cycles. The resin synthesized can be used for water softening.

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