Exploitation of chloride ion selective electrode for determination of some chloro-oxygenated agents with iodide in the acidic medium.

Abstract

It was confirmed in this research that Cl¯ ISE was successfully used in the determination of chloro-oxygenated agents involving hypochlorite, chlorite, chlorate and perchlorate in their individual and mixture aqueous solutions. The results obtained are comparable to those obtained by Pt electrode since the reactions are oxidation-reduction reactions at which Pt electrode responds directly to potential change of these reactions. The response of Cl¯ ISE was slower than the response of Pt electrode, because with Cl¯ ISE the liberated Cl¯ was distributed in the solution toward the electrode membrane where the potential response takes place as a result of ion exchange with chloride electrode membrane. As a result the error percentages are positive with Cl¯ ISE. In case of Pt electrode it is directly responded to potential difference through potentiometric titration therefore, the response at equivalence point is clear. The potentiometric titration with both electrodes gave clear jump at equivalence point and the titration curves are in S forms. Good and encouraging results were obtained with concentrated solutions as well as with diluted solutions of these agents. While the first and second derivatives offered more accurate equivalence points. The results obtained with individuals and mixtures of the chloro-oxygenated agents were almost the same or close to each other and the variance was attributed to practical errors. Both electrodes were applied for determination of hypochlorite in commercial bleaching solution. The electrodes offered result lower than that on bottle label. These may be due to wasting of the compound by high temp., transferring and agitation of the solution.