Complexation of neptunium(V) by salicylate, phthalate and citrate ligands in a pH 7.5 phosphate buffered system

Rees, TF; Daniel, SR

HERO ID

1599490

Reference Type

Journal Article

Year

1984

Language

eng

HERO ID 1599490
In Press No
Year 1984
Title Complexation of neptunium(V) by salicylate, phthalate and citrate ligands in a pH 7.5 phosphate buffered system
Authors Rees, TF; Daniel, SR
Journal Polyhedron
Volume 3
Issue 6
Page Numbers 667-674
Abstract HEEP COPYRIGHT: BIOL ABS. Models which predict the geochemical behavior of Np in nuclear waste require thermodynamic parameters and stability constants. Conditional stability constants, enthalpies %W%000004%% and entropies %W%000004%% of complexation at pH 7.5 and ionic strength 0.1 were determined for Np (V) complexes of phosphate, salicylate, phthalate and citrate. Phosphate formed a complex with log beta = 2.36 | 0.42 at 25? C, %W%000004%% = -69.9 kJ/mol and %W%000004%% = -188 J/mol-K. At pH 7.5 salicylate did not for complex with Np(V) due to the low charge density of the NpO2+ ion and incomplete ionization of the salicylate ion. Phthalate formed a complex with log beta = 3.43 | 0.33 at 25? C, %W%000004%% = 33.5 kJ/mol and %W%000004%% = 182 J/mol-K. Citrate forms a complex with log beta = 4.84 | 0.72 at 25? C, %W%000004%% = 14.0 kJ/mol and %W%000004%% = 140 J/mol-K. In all cases, only 1:1 complexes were identified.
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Language Text eng