| Abstract: | The rate of reduction of plutonium(VI) and neptunium(VI) by bisulfide ion in neutral and mildly alkaline solutions has been investigated by the stopped-flow technique. The reduction of both of these ions to the pentavalent oxidation state appears to occur in an intramolecular reaction involving an unusual actinide(VI)-hydroxide-bisulfide complex. For plutonium the rate of reduction is 27.4 (??4.1) s-1 at 25??C with ??H* = +33.2 (??1.0) kJ/mol and ??S* = -106 (??4) J/(mol K). The apparent stability constant for the transient complex is 4.66 (??0.94) ?? 103 M-1 at 25??C with associated thermodynamic parameters of ??Hc = +27.7 (??0.4) kJ/mol and ??Sc = +163 (??2) J/(mol K). The corresponding rate and stability constants are determined for the neptunium system at 25??C (k3 = 139 (??30) s-1, Kc. = 1.31 (??0.32) ?? 103 M-1), but equivalent parameters cannot be determined at reduced temperatures. The reaction rate is decreased by bicarbonate ion. At pH > 10.5, a second reaction mechanism, also involving a sulfide complex, is indicated. ?? 1986 American Chemical Society. |
| Genre: | Article |
| ProdID: | 70015177 |
| Citation Author: | Nash, K. L.; Cleveland, J. M.; Sullivan, J. C.; Woods, M. |
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| Citation End Page: | 1173 |
| Citation Issue: | 8 |
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| Citation Language: | English |
| Citation Larger Work Title: | Inorganic Chemistry |
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| Citation Number Of Pages: | 5 |
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| Citation Search Results Text: | Kinetics of reduction of plutonium(VI) and neptunium(VI) by sulfide in neutral and alkaline solutions; 1986; Article; Journal; Inorganic Chemistry; Nash, K. L.; Cleveland, J. M.; Sullivan, J. C.; Woods, M. |
| Citation Start Page: | 1169 |
| Citation Volume: | 25 |
| Citation Year: | 1986 |
| Type: | citation/reference |
| Text: | Kinetics of reduction of plutonium(VI) and neptunium(VI) by sulfide in neutral and alkaline solutions; 1986; Article; Journal; Inorganic Chemistry; Nash, K. L.; Cleveland, J. M.; Sullivan, J. C.; Woods, M. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Wed, 1 Jan 1986 00:00 -0600 |
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