CATHODIC REDUCTION OF HYPOCHLORITE DURING REDUCTION OF DILUTE SODIUM-CHLORIDE SOLUTION

Sodium chloride solutions of concentration 15 and 30 g dm(-3) were ele ctrolysed in a flow-through electrolyser with a titanium/TiO2/RuO2 ano de at current densities 1059-4237 A m(-2). The current yield for the r eduction of hypochlorite on a stainless steel cathode was found to be 13-32% at 7 g dm(-3) NaClO, in agreement with that calculated on the b asis of the Stephan-Vogt theory. Migration of ions was taken into acco unt, the diameter of hydrogen bubbles was set equal to 0.04mm and the coverage of the electrode with the bubbles was estimated as =theta 0.8 97. The results of calculations show that the reduction rate of hypoch lorite at low NaCl concentrations is lowered by migration. Literature data for the reduction of hypochlorite are in accord with the current yield calculated on the basis of the Stephan-Vogt theory using theta = 0.787 and theta = 0.949.