Hydrogen reduction of metal ions: An electrochemical model

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Abstract

Rate laws for the hydrogen reduction of metal ions are typically of the form: r = -d[M(II)]/dt = k[M(II)]xPH2y where k is an apparent rate constant, [M(II)] and PH2 represent dissolved metal concentration and hydrogen pressure respectively, while x = 0 - 1 and y = 0.5 - 2. Half-order dependences have been reported for some M(II)/H2 systems; however, no satisfactory explanations have been offered. In an effort to bridge this gap in our understanding, the published precipitation rate data (for M(II) = Cu(II), Ni(II), and Co(II)) are reviewed (with emphasis on the reported reaction orders) and compared with the corresponding but limited electrochemical polarization data. Based on the available literature on the electrochemical kinetics of the M/M(II) and H2/H+ systems it is demonstrated theoretically that, under certain conditions (e.g., in the presence of electron-conducting solids), the rate of the M(II)/H2 reaction can be expressed as: -d[M2+]/dt = k[M2+] 1/2PH21/2 It is concluded that electrochemical processes probably play an important role in the hydrogen reduction of metal ions, especially for systems that involve heterogeneous catalysis.

Original languageEnglish (US)
Pages1151-1165
Number of pages15
Publication statusPublished - Dec 1 2003
EventHydrometallurgy 2003: Proceedings of the 5th International Symposium - Vancouver, BC, Canada
Duration: Aug 24 2003Aug 27 2003

Other

OtherHydrometallurgy 2003: Proceedings of the 5th International Symposium
CountryCanada
CityVancouver, BC
Period8/24/038/27/03

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All Science Journal Classification (ASJC) codes

  • Filtration and Separation

Cite this

Osseo-Asare, K. (2003). Hydrogen reduction of metal ions: An electrochemical model. 1151-1165. Paper presented at Hydrometallurgy 2003: Proceedings of the 5th International Symposium, Vancouver, BC, Canada.