Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Osao Sumita

Yasumasa Furutani

Yasuo Hira

Akira Minato

Takashi Hasegawa

Masahito Kobayashi

Hisao Itow

Masayuki Saito

Hisao Itou

Saburo Shoji

An object to-be-washed bearing an oxide on the surface of a parent material metal is immersed in a liquid containing a complexing agent, electrons having energy levels on the base side with respect to the Fermi level of the oxide are generated outside the parent material metal by supplying external energy, and the electrons are injected into the oxide of the object to-be-washed immersed in the liquid.

Method of removing oxide on metal surface

The present invention provides a process for removing a metal surface oxide from a metallic substance by contacting the metal surface oxide layer with a deterging liquid to introduce electrons into the metal surface oxide in contact with the deterging liquid to dissolve the metal surface oxide, which process is characterized in that a metal piece or carbon piece is immersed in the deterging liquid into which gaseous hydrogen has been introduced and the metal piece or carbon piece is electrically connected to the metal surface oxide on the metallic substance. The metal piece is preferably platinum or vanadium. A preferred deterging liquid is one having a pH of about 5 to 7 and containing a complexing agent.

Process for removing metal surface oxide

A cleaning fluid such as a chemical decontamination solution originally containing one or more cleaning or decontamination reagents in low concentrations and deteriorated after a cleaning or decontamination treatment step by containing metal oxides therein can be regenerated by introducing such a deteriorated cleaning fluid into an electrolytic cell, passing a direct current through said cleaning fluid between two electrodes, and removing said metal oxides by depositing dissolved metal ions on the cathode as metals from the cleaning fluid.

Process for regenerating cleaning fluid

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Hitachi, Japan

Osao Sumita