Tosoh Corporation

Takashi Sakaki

Kazumasa Suetsugu

Kanji Yoshimitsu

Kazuhisa Yamaguchi

Satoshi Yoshida

Yukinori Sudo

Hideharu Horikoshi

To provide a method for recovering a precious metal from a solution containing precious metal ions, an extracting agent or adsorbent used therefor, and a back-extracting agent or desorbent. An extracting agent or adsorbent in which precious metal ions are extracted or adsorbed, is brought into contact with a back-extracting agent or desorbent containing a sulfur-containing amino acid derivative represented by the following formula (I): wherein Ris a methyl group, an ethyl group, a vinyl group, a Clinear, branched or cyclic hydrocarbon group, or a Caromatic hydrocarbon group, R's are each independently a hydrogen atom, a methyl group, an ethyl group, a vinyl group, a Clinear, branched or cyclic hydrocarbon group or a Caromatic hydrocarbon group, and n is 0 or 1, to obtain a solution containing the precious metal ions, which is subjected to a reduction treatment to obtain a precious metal.

Method for recovering precious metal from solution containing precious metal ions, extracting agent or adsorbent used therefor, and back-extracting agent or desorbent

A cathode of sufficiently low hydrogen overvoltage is provided which is useful in electrolysis of water or of an aqueous alkali metal chloride solution such as a sodium chloride solution. A process for producing the cathode is also provided. The low hydrogen overvoltage cathode has an electroconductive base material coated with an alloy layer containing nickel and molybdenum, the alloy layer containing the nickel at a content ranging from 35 to 90% by weight and the molybdenum at a content ranging from 10 to 65% by weight. The alloy laser has an X-ray diffraction (CuK.alpha. line) pattern with a main peak at an angle ranging from 42 to 45.degree. with a peak half width ranging from 0.4 to 7.degree.. One process for producing the low hydrogen overvoltage cathode of the present invention involves plating an electroconductive base material by an arc discharge type ion plating method. Another process for producing the low hydrogen overvoltage cathode of the present invention involves co-electrodepositing nickel and molybdenum onto an electroconductive base material in a plating bath.

Low hydrogen overvoltage cathode and process for the production thereof

A novel cathode of low hydrogen overvoltage is provided which is useful for electrolysis of water and electrolysis of an aqueous alkali metal chloride such as sodium chloride. A process for producing the cathode is also provided. The low hydrogen overvoltage cathode comprises an electroconductive base material; and a coating layer containing at least one organic compound selected from the group consisting of amino acids, monocarboxylic acids, dicarboxylic acids, monoamines, diamines, triamines, and tetramines, and derivatives thereof at a content of from 0.5% to 18% by weight in terms of carbon, and a metal component selected from the group consisting of nickel, nickel-iron, nickel-cobalt, and nickel-indium at an indium content ranging from 1% to 90% by weight. The process for producing the low hydrogen overvoltage cathode comprises conducting electrodeposition to form a coating layer on a surface of an electroconductive base material in a plating bath containing at least nickel ions, nickel and iron ions, nickel and cobalt ions, or nickel and indium ions, and containing additionally at least one organic compound selected from the group consisting of amino acids, monocarboxylic acids, dicarboxylic acids, monoamines, diamines, triamines, and tetramines, and derivatives thereof.

Low hydrogen overvoltage cathode and process for production thereof

A low hydrogen overvoltage cathode is provided which comprises an electroconductive base material coated with an alloy layer containing cobalt and tin at least at a content of tin ranging from 0.01 to 95% by weight. A process is also provided for producing the low hydrogen voltage cathode, wherein cobalt and tin at least are electrolytically co-deposited onto a surface of an electroconductive base material from a plating bath containing cobalt ions, tin ions, and a complexing agent.

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Yamaguchi, Japan

Takashi Sakaki