[Redoxpotential and germicidal action of aqueous halogen solution (author transl)].

Abstract

Methods are given to calculate the equilibrium concentrations of both halogene solutions (chlorine, bromine and iodine) in the presence of additional halide and of chlorine solutions in the presence of chloride and ammonia. With the aid of these values and the redoxpotentials which have been determined from them is demonstrated that there is a very complicated connection between the latters and the total as well as the equilibrium concentrations. It depends on the kind of the halogene, the pH-value and the presence of substances which can react with the halogene (halides, NH-compounds) and can not be described by the simple formula: increase of the redoxpotential approximately increase of the equilibrium concentrations of germicidal hydrolysis products and as a consequence of the death rates. On the contrary a reduction of the total halogene concentration may cause an increase of the redoxpotential as well as the addition of halide may lower the redoxpotential while the concentration of strong germicidal "free halogene" remains unchanged. The redoxpotential therefore is not a mean to make reliable predictions concerning the germicidal action of halogene solutions.