| abstract |
A method for controlling the hydrogen ion concentration of an aqueous solution is provided, which method comprises adding to an aqueous solution, microcapsules prepared by encapsulating an acid material with a polymer, which is dissolved in or swelled with water in an alkaline state only, and/or microcapsules prepared by encapsulating an alkaline material with a polymer, which is dissolved in or swelled with water in an acid state only, and adding an aqueous acid solution or an aqueous alkaline solution to the system. |