Abstract

Three methods for determining Cl‐ion concentrations in neutral, alkaline and alkaline sulphite solutions were tested and the results are reported. The Cl‐ ion ‐ selective electrode was found to be the only suitable method for alkaline sulphite solutions, and reasons for this are given. This method was further evaluated in practice monitoring the progress of desalination using sodium hydroxide and alkaline sulphite solutions. The total amount of Cl‐ ions removed during the treatment was calculated and the residual concentration in the treated object measured using ion chromatography.