Redox copolymer with N‐bromosulfonamide groups for the decomposition of cyanide ions in dilute aqueous solutions

Abstract

AbstractA redox copolymer, macroporous poly(styrene‐co‐divinylbenzene) (S/DVB) resin having N‐bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g−1, i. e. 3.72 meq g−1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non‐toxic compounds. The reactions were carried out in aqueous media containing 26–2600 mg L−1 CN− at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000‐times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L−1 CN−. During the oxidation processes the SO2NBrNa groups transform to SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N‐bromosulfonamide resin, the oxidation of these ions by N‐chlorosulfonamide resin with addition of a small amount of bromides was examined.