Patent ID: 8685147

Claim:
A method for producing an aqueous sodium hypochlorite solution, the method comprising the step of causing a chlorine gas and an aqueous sodium hydroxide solution to react with each other, the chlorine gas being produced by a method including the steps of: (A) washing a chlorine gas that contains bromine, in a gas washing unit comprising a packed column or a tray tower, wherein the chlorine gas introduced via a lower part of the gas washing unit is brought into counterflow gas/liquid contact with a liquid chlorine introduced via an upper part of the gas washing unit; and (B) taking out a purified chlorine gas thus washed, via the upper part of the gas washing unit, wherein a weight ratio of the chlorine gas relative to the liquid chlorine introduced in the step (A) is 1/1.0 to 1/0.3, an aqueous sodium hypochlorite solution having a bromic acid content of not more than 30 mg/L is obtained, and temperature of the liquid chlorine introduced via the upper part of the gas washing unit is controlled so as not to vaporize under pressure in the gas washing unit when introduced to the gas washing unit.