Patent ID: 8273236

Claim:
A method for producing a carbonic acid gas solution comprising electrolyzing, in an electrolytic cell with electrodes, a first aqueous solution to a pH value of 6 or higher by applying a DC voltage between the electrodes, to form an oxidation field state short of electrons in the aqueous solution; and mixing a second aqueous solution with a carboxylic acid dissolved therein into the first aqueous solution in the oxidation field state, so that the first aqueous solution in the oxidation field state obtains electrons and is deoxidized, and the carboxylic acid is oxidized, to produce carbonic acid gas, wherein, after the first aqueous solution is electrolyzed to a pH value of 6 or higher, an acidic solution is added thereto to adjust the pH value of the first aqueous solution into a range of 5-7, and then, the second aqueous solution is added thereto to keep the pH value within the range of 5-7.