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Robert C. Moore, Kathleen Holt, Hongting Zhao, Ahmed Hasan, Nasser Awwad, Mona Gasser, Charles Sanchez
Sorption of Np(V) by synthetic hydroxyapatite
The sorption of Np(V) to synthetic hydroxyapatite was determined in batch experiments in a 0.1M NaClO4 solution. The hydroxyapatite used was of high purity as determined by SEM, EDS, XRD, FT-IR and ICP-MS analysis. Results from kinetic experiments with an initial Np(V) concentration of 1×10-7 to 1×10-6M indicate the sorption process is relatively fast with more than 90 of the Np(V) being sorbed in approximately 3 hours. Equilibrium experiments performed over the pH range of 6 to 11 indicated sorption is strongly pH dependent with distribution coefficients, Kd values (mL/g), increasing from 123L/mole at pH 6 to 69200L/mole at pH 8.5. Kd values are observed to decrease as pH further increases. Data points over a range of Np(V) concentrations were collected at pH 8 and fitted to the Langmuir isotherm model for simple adsorption. The Langmuir equation gave an excellent representation of the data. Langmuir parameters were determined to be Ca=0.032mole/mole and K=1.22×106L/mole, indicating the high affinity of hydroxyapatite for Np(V) adsorption.
Radiochimica Acta, Oldenbourg Wissenschaftsverlag
Print ISSN: 0033-8230
Volume: 91, 12/2003
Pages: 721