Oxidation of arsenite in aqueous solutions by redox copolymer with N-bromosulfonamide functional groups

Abstract

Macromolecular oxidant [P]-SO2NBrNa (a macroporous styrene/divinylbenzene copolymer containing N-bromosulfonamide functional groups in the sodium form) was synthesized and used to oxidize arsenites to arsenates in dilute aqueous solutions. The oxidant, containing active bromine (1.65mmol/g) in its functional groups, was obtained through the transformation of Amberlyst 15 (Rohm and Haas) commercial cation exchanger’s sulfonic functional groups. The batchwise method and the column method and NaAsO2 solutions (375, 93 and 10mg As(III)/dm3) in water alone and in 0.01M NaOH were used in the investigations. Special potentiometric, reductometric measurements showed that the investigated oxidation reaction was favoured by a weak acidic to weak alkaline medium. The determined redox potential of the resin was 440mV at pH=6.3 and 130mV at pH=11.01. In the column process experiments, conducted using NaAsO2 solutions with a concentration of 10mg As(III)/dm3 at a flow rate of 6BV/h, a breakthrough (defined as the exceedance of 0.01mg As(III)/dm3 in the effluent) would occur after the solutions amounting to about 1700 bed volumes were passed though the column.