Determination of Chlorine Dioxide in Process Gas with a Large Excess of Chlorine by a Voltammetric Membrane Electrode.

Abstract

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 coexisting chlorine, and the third one contained dimethylsulfoxide (DMSO) to capture ClO2. DMSO was useful as an absorbing solution for ClO2, because more ClO2 was captured and remained in DMSO than in water. Moreover, DMSO eliminated interference from the coexisting chlorine. ClO2 collected in water was determined by a voltammetric membrane electrode after the addition of DMSO. Chlorine was determined by colorimetry using o-tolidine. The concentrations of ClO2 and chlorine in process gases ranged from 36 to 116 mg/m3 and from 16 to 51 g/m3, respectively.