Abstract: A dry ion exchange resin manufacturing method includes: obtaining a purified cation exchange resin by bringing a cation exchange resin to be purified into contact with a mineral acid solution having a metal impurity content of 1 mg/L, or less and a concentration of 5% by weight or more, to purify the cation exchange resin, wherein a total metal impurity elution amount eluted when hydrochloric acid having a concentration of 3% by weight is passed through the purified cation exchange resin with a volume ratio of 25 times is at most equal to 5 ?g/mL-R; and a drying step of drying the purified cation exchange resin under reduced pressure at 80° C. or lower until the moisture content is at most equal to 5% by weight.

Abstract: The present invention provides a method for purifying a liquid to be treated, the method being capable of reducing the content of metal impurities in the liquid to be treated containing tetraalkylammonium ions, and further, being capable of suppressing cracking of the resin even when a strongly acidic cation exchange resin is used. The method includes: an impurity removal step of passing a liquid to be treated that contains tetraalkylammonium ions and metal impurities through a container filled with a cation exchange resin of a hydrogen ion form or a tetraalkylammonium ion form to reduce the content of the metal impurities in the liquid to be treated, wherein the degree of cross-linking of the cation exchange resin is from 16% to 24%.

Abstract: A method for purifying a non-aqueous solvent includes: pretreating by passing a non-aqueous solvent for dehydration treatment through a packed bed of an ion exchange resin that is not yet subjected to dehydration treatment, to remove water in the ion exchange resin; and purifying by passing a non-aqueous solvent to be purified through the packed bed of the ion exchange resin from which water is removed during the pretreating, to purify the non-aqueous solvent to be purified, in which the harmonic-mean particle size of the ion exchange resin is 0.20 to 0.50 mm. According to the present application, a method for purifying a non-aqueous solvent can be provided, the method includes pretreating by removing water in a water-containing ion exchange resin by passing therethrough a non-aqueous solvent for dehydration treatment, in which the amount of the non-aqueous solvent for dehydration treatment used during the pretreating is small.