Abstract: There is herein disclosed a method for preparing high-purity aqueous hydrogen peroxide by bringing aqueous hydrogen peroxide into contact with a strongly basic anion exchange resin, said method comprising the step of using the strongly basic anion exchange resin which is converted into a form of an exchange group at the time of the purification of aqueous hydrogen peroxide by bringing the strongly basic anion exchange resin into contact with a liquid agent passed through a filter having an average pore diameter of 1.0 .mu.m or less.According to the present invention, aqueous hydrogen peroxide containing inorganic impurities such as metals and metallic compounds can be purified to prepare extremely high-purity aqueous hydrogen peroxide.

Abstract: A process for purifying an aqueous solution of hydrogen peroxide comprising bringing the aqueous solution of hydrogen peroxide into contact with a cation exchange resin or an anion exchange resin, aging the obtained intermediately purified aqueous solution of hydrogen peroxide by standing alone for 1 hour or more, and bringing the aged aqueous solution of hydrogen peroxide into contact with an ion exchange resin of the same type.The process provides a high purity aqueous solution of hydrogen peroxide and can advantageously be used in the field of production of semiconductors.

Abstract: An efficient method is proposed for the preparation of a highly purified aqueous hydrogen peroxide solution, which can be used even in a semiconductor process, from a crude aqueous solution containing metallic and inorganic impurities. The method comprises the steps of: (a) acidifying the crude solution by the addition of a specific amount of an acid such as sulfuric and nitric acids; and (b) passing the acidified crude solution through a column filled with a strongly acidic cation-exchange resin in the hydrogen-form or a mixture of the same with a strongly basic anion-exchange resin in the hydroxy-, carbonate- or hydrogencarbonate-form in a specified volume proportion so that the impurities are removed by ion-exchange. The efficiency of this purification treatment can be further enhanced by keeping the acidified crude solution for a certain length of time of, for example, at least 6 hours prior to the ion-exchange treatment in step (b).