Studies on role of oxygen in the adsorption of Au(CN) 2 − and Ag(CN) 2 − onto activated carbon

Tsuchida, N. and Muir, D.M. (1986) Studies on role of oxygen in the adsorption of Au(CN) 2 − and Ag(CN) 2 − onto activated carbon. Metallurgical Transactions B, 17 (3). pp. 529-533.

Abstract

Comparative studies of the adsorption of Au(CN) 2 − , Ag(CN) 2 − , and Hg(CN) 2 − onto activated carbon (Norit R2020) have suggested that oxygen and oxygen containing surface functional groups play a role in the adsorption process of Au(CN) 2 − and Ag(CN) 2 − but not in the adsorption of Hg(CN) 2 − . Adsorption of Au(CN) 2 − and Ag(CN) 2 − on carbon degassed at 950 °C under 10−5 torr (1.33 × 10−3 P) vacuum is decreased by 50 pct compared with the adsorption on normal activated carbon. However, in the presence of oxygen in solution, the degassed carbon adsorbs Au(CCN) 2 − to the same extent as normal carbon. The effect of organic solvents and the variation in the potential of the two types of carbon upon adsorption of Au(CN) 2 − were also investigated. These results indicate that activated carbon behaves like an ion-exchange resin but is capable of oxidizing cyanide and cyanide complexes by chemisorbed oxygen. A dual mechanism for the adsorption of Au(CN) 2 − and Ag(CN) 2 − onto activated carbon is therefore proposed, in which cyanide complexes adsorb on carbon by anion exchange with OH− followed by partial oxidative decomposition of Au(CN) 2 − or Ag(CN) 2 − to insoluble AuCN or AgCN.

Item Type:	Journal Article
Publisher:	ASM International
URI:	http://researchrepository.murdoch.edu.au/id/eprint/20564

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