METHOD FOR PURIFYING WATER-SOLUBLE COLORANT

摘要

PROBLEM TO BE SOLVED: To provide a method for removing an ion in an aqueous solution by which a bivalent or higher metal ion co-existing in an aqueous solution of a dye or an acid group-containing derivative of a pigment is efficiently removed. SOLUTION: The method for purifying a water-soluble colorant solution comprises circulating an aqueous solution of the water-soluble colorant containing as an impurity a bivalent or higher metal ion in a magnetic field of at least 5,000 gauss and subsequently removing the bivalent or higher metal ion co-existing in the aqueous solution by a chelate exchange resin.