JPS57100915A - Purification of aqueous solution of alkali chloride - Google Patents

Abstract

PURPOSE:To remove Ca, Mg, etc. at high adsorption rate until their amounts are extremely small concentrations, by adding a caustic alkali to an aqueous solution of an alkali chloride to give the aqueous solution of an alkali chloride with most Ca, Mg, etc. precipitated and separated, bringing this aqueous solution into contact with an aminoalkylphosphoric acid group type chelate resin having specific physical properties. CONSTITUTION:An aqueous solution of an alkali chloride to be treated by electrolysis is pretreated by a wellknown method, for example, it is treated with a caustic alkali and/or an alkali carbonate, and, if necessary, with phosphoric acid and/or phosphate, so that most Ca, Mg, etc. are precipitated and separated. This previously purified aqueous solution of an alkali chloride is passed through a resin column preferably packed with the above-mentioned chelate resin, so that metal ions, e.g., Ca, Mg, etc. are adsorbed on the chelate resin and removed. A chelate resin having physical properties of >=0.2cc/g pore volume having pore diameters of >=500A is used as the chelate resin. Consequently, for example, the concentration of metal ion, e.g., Ca, Mg, etc. in the aqueous solution of an alkali chloride can be reduced to a concentration adaptable for common electrolysis, namely <=0.1mg/l.