DETERMINATION OF CHLORINE DIOXIDE IN-PROCESS GAS WITH A LARGE EXCESS OF CHLORINE BY A VOLTAMMETRIC MEMBRANE-ELECTRODE

Chlorine dioxide (ClO2) in a gas exhausted from a factory involved in the electrolytical soda process was measured. Three absorbing vessels connected in series were used for the simultaneous collection of ClO2 and chlorine. Two vessels contained water to collect ClO2 and coexisti ng chlorine, and the third one contained dimethylsuIfoxide (DMSO) to c apture ClO2. DMSO was useful as an absorbing solution for ClO2, becaus e more ClO2 was captured and remained in DMSO than in water. Moreover, DMSO eliminated interference from the coexisting chlorine. ClO2 colle cted in water was determined by a voltammetric membrane electrode afte r the addition of DMSO. Chlorine was determined by colorimetry using o -tolidine. The concentrations of ClO2 and chlorine in process gases ra nged from 36 to 116 mg/m(3) and from 16 to 51 g/m(3), respectively.