Electrochemical Determination of Dissolved Chlorine in a Strong Acidic Electrolyte

Abstract

An amperometric sensor for monitoring aqueous dissolved chlorine in a strong acidic electrolyte containing reducible Bi³⁺ was developed. Cyclic voltammograms of a porous carb on electrode coated with RuO₂ were measured in strong acidic electrolytes containing no molecular chlorine with and without Bi³⁺. The applicable potential to measure the reduction current of dissolved molecular chlorine without the interference by Bi" was determined to be ca. O.50 -ca.0.80 V vs. Ag/AgCl/3.3 mol. dm^-3KC1. When a potential in the region was applied to the developed sensor, into which the sample electrolytes including molecular chlorine were flowed, the detected current was proportional to the concentration of dissolved chlorine at a constant temperature irrespectively of the presence of Bi³⁺. Plotting natural logarithm of current against the reciprocal of temperature gave a straight line with the slope of ca.4.3 kcal.mol^-1, which corresponds to the activation energy on diffusion of dissolved molecular chlorine. The obtained value for a dissolved chlorine concentration coincided with the theoretical one. Concerning the measurement of the concentration of dissolved chl orine in a strong acidic electrolyte in a larger zinc-chlorine secondary battery system for electric power storage, the utilization of the sensor was tested in a real scale. Research and Development on a Dissolved Chlorine Sensor. I.