A macromolecular N, N-dichlorosulfonamide as oxidant for cyanides

Abstract

The possibility of the use of a redox copolymer—a macroporous poly(styrene-co-divinylbenzene) resin having N, N-dichlorosulfonamide groups—as macromolecular oxidant for destruction of cyanide ions contained in dilute aqueous solutions has been investigated in this report. The resin contains two atoms of active chlorine in functional groups and shows strong oxidising properties. It was employed in static and flow systems for transformation of cyanide ions to non-toxic compounds. The reactions were carried out in aqueous media containing 26–2600 mg CN −/dm 3 at pH in the range 10–14. The data showed that the macromolecular oxidant easily decomposes cyanides forming cyanates which are unstable in aqueous solutions—they hydrolyse to carbonates and ammonia. Both of the two atoms of active chlorine attached to the sulfonamide group of the reactive copolymer show oxidising properties in relation to cyanide ions but their activity is different in examined conditions. In strong alkaline medium one of these atoms easily quits the resin phase and instantly oxidises cyanides, whereas the second of them bound more strongly oxidises cyanide in static condition in a longer time. To utilise with good efficiency both of the two atoms of active chlorine for destruction of cyanide ions in processes carried out in flow systems it is necessary to maintain the level of basicity of the influent as low as possible.