METHOD FOR PURIFYING AQUEOUS ALKALINE SOLUTION

摘要

Disclosed is a method for purifying an aqueous alkaline solution which is characterized in that metal components other than alkali metals and alkaline earth metals are removed from an aqueous alkaline solution by bringing a fibrous activated carbon into contact with the aqueous alkaline solution. Also disclosed is an apparatus for purifying an aqueous alkaline solution. By such a method, metal impurities such as Ni and iron in the aqueous alkaline solution can be reduced to such an extent that the aqueous alkaline solution can be used as an etching agent for silicon wafers.