Abstract: A chromium plating method using a plating bath comprising trivalent chromium and an electrode which is an anode comprising an electrode substrate of titanium, tantalum, zirconium, niobium or an alloy thereof, coated with an electrode catalyst comprising at least iridium oxide and, optionally, at least one of titanium, tantalum, niobium, zirconium, tin, antimony, ruthenium, platinum, cobalt, molybdenum, tungsten or an oxide thereof. The anode may be placed directly in the chromium plating bath or may be placed in an anode chamber partitioned from the chromium plating bath with an ion-exchange membrane. The chromium plating method may be a barrel plating method.

Abstract: A method for the electrolytic pickling or degreasing of a steel plate in an aqueous solution having an electrode disposed therein, wherein an insoluble electrode or a ferrite electrode is used as the electrode, said insoluble electrode comprising an electrically conductive substrate having provided thereon directly or through an intermediate layer, an electrode coating containing a platinum group metal or an oxide thereof.

Abstract: An electrode for use in electrolysis is disclosed, which comprises a metallic substrate having formed on the surfaces thereof, in sequence, an amorphous layer free of grain boundaries, and an active electrode material coating. The electrode shows excellent durability even when used in electrolysis accompanied by oxygen evolution. A process for producing the electrode is also disclosed.

Abstract: A process for recovering sulfuric acid from an aqueous sulfuric acid solution containing ferrous sulfate is disclosed, which comprises electrolyzing the aqueous sulfuric acid solution containing ferrous sulfate to thereby oxidize ferrous ion dissolved in the solution to ferric ion, and then removing the ferric ion by solvent extraction using a solvent and an extractant.