You are here: Home :: Area NEM :: Chemistry :: Physical chemistry

P. Thakur, Robert C. Moore, Gregory R. Choppin

Np(V)O₂⁺ sorption on hydroxyapatite-effect of calcium and phosphate anions

Keywords: NpO2+, Sorption, Hydroxyapatite, Kinetics, Thermodynamics

The sorption of NpO₂⁺ from aqueous solution on hydroxyapatite was studied as a function of the amount of sorbent, initial NpO₂⁺ concentration, ionic strength and pcH. The hydroxyapatite was characterized by SEM, EDS, XRD, FT-IR and ICP-MS measurements. At ionic strengths of 0.10 to 5.00 M NaClO₄, the sorption increased with increased pcH to a maximum between pcH 8−8.5, then decreased as the pcH increased.

The kinetics of NpO₂⁺ sorption on hydroxyapatite followed Lagergren first order kinetics. The temperature dependence of sorption was small in the range of 273−283 K, but increased more sharply at higher temperatures of 298−333 K. The heat of sorption of NpO₂⁺ was endothermic and the free energy values were exothermic indicating large, positive entropy. The activation energy for the sorption process was calculated to be 29.52±1.2 kJ/mole. The effect of calcium and phosphate on NpO₂⁺ sorption was studied as a function of concentration and pcH.

Radiochimica Acta, Oldenbourg Wissenschaftsverlag

Print ISSN: 0033-8230
Volume: 94, 09/2006
Pages: 645 - 649

Show full article (external site)

Show all available items of this journal

 

Area NEM