Studies on the Catalytic Action of Mineral Springs. III

On the Catalatic Action of Artificial Acidic Iron Solution. (3). Inhibitory Action of Halide Ion and Phosphate Ion

Abstract

The catalatic action of artificial mineral spring containing sodium chloride and iron alum is weaker than that not containing sodium chloride, which shows that the catalatic action of iron is inhibited by chlorine ion as well. The degree of this inhibition is a function of sulfate ion concentration in the mineral water. There is no inhibitory action when the total concentration of sulfate ion is less than twice the total concentration of iron ion but the action appears when this becomes more than twice. The mechanism of this inhibition is thought to be the increase of effective concentration of sulfate ion by the presence of chlorine ion.
Inhibitory action of bromine ion is stronger than that of chlorine ion and is observed even when there is no inhibition by chlorine ion. Inhibition by iodine ion is 500 times greater than that of bromine ion. When liberation of iodine is observed on addition of hydrogen peroxide to mineral water, iodine promotes catalatic action. Presence of dihydrogen phosphate ion results in formation of a complex salt with ferric ion and this lowers the concentration of ferric ion, thereby inhibiting its catalatic action.