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Abstract

The electronics industry demands that hydrogen peroxide for use therein be purified to very low levels of impurities, currently at the level of a few ppb for some impurities, or even lower. However, existing methods are either inherently unsafe because they bring concentrated hydrogen peroxide into contact with a concentrate of transition metal decomposition agents for peroxide and a purification resin which acts as a source of carbon, or are unable to attain the desired impurity level. In the instant purification process, the hydrogen peroxide solution is passed through a membrane having a very small pore size which contains an ion exchange resin that is capable of removing alkali and alkaline earth metal ions from solution. The feed solution in characterized in that it contains no more than a small proportion by weight of transition metals that catalyse hydrogen peroxide decomposition compared with the total metals content. The feed solution in some embodiments results from a prior treatment of an iron or copper contaminated solution with a dispersion of stannic oxide.

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