METHOD FOR PREPARING HYPOCHLOROUS ACID AQUEOUS SOLUTION AND METHOD FOR REGENERATING WEAKLY ACIDIC CATION EXCHANGER

摘要

Provided is a method for preparing a hypochlorous acid aqueous solution by which a weakly acidic hypochlorous acid aqueous solution having a pH of about 3.5-7 can be obtained without substantially generating chlorine gas even immediately after regeneration or even with a new weakly acidic cation exchange resin.　In a method for preparing a hypochlorous acid aqueous solution wherein an aqueous solution of hypochlorite is brought into contact with a weakly acidic cation exchanger to exchange cations constituting the hypochlorite with hydrogen ions to increase the concentration of hypochlorous acid in the aqueous solution, a neutral salt solution of a strong acid and a strong base in an amount that may obtain the hypochlorous acid aqueous solution having a pH of at least 3.5 when the hypochlorite aqueous solution is brought into contact with the weakly acidic cation exchanger is brought into contact, prior to the contact between the hypochlorite aqueous solution and the weakly acidic cation exchanger, with a weakly acidic cation exchanger that has been regenerated or has not been substantially subjected to cation exchange.