ELECTROSYNTHESIS OF SODIUM HYDROSULFITE - I - DEVELOPMENT OF AN ONLINE PROCESS-CONTROL MONITOR

Sodium hydrosulfite is an important industrial reducing agent widely u sed in the textile, clay, and pulp and paper industries. Electrochemic ally produced sodium hydrosulfite contains levels of sodium thiosulfat e contamination that are of concern for many applications. In this rep ort, a novel online process monitor specifically designed for use unde r the conditions of industrial scale, electrolytic sodium hydrosulfite manufacture is described. This monitor enables the determination of ( i) hydrosulfite under acidic conditions, (ii) hydrosulfite in the pres ence of a large excess of bisulfite, and (iii) trace quantities of thi osulfate in the presence of a thousand-fold excess of hydrosulfite. An alyte concentrations are determined by square wave voltammetry in a fl owing stream.