Detection and identification of solids, surfaces, and solutions of uranium using vibrational spectroscopy.

The infrared reflectance spectra of the third phases formed in the systems UO2(NO3)2/HNO3/20%TBP in n-dodecane and Th(NO3)4/HNO3/20%TBP in n-octane gave evidence for the presence in solution of a significant amount of weakly bonded molecular nitric acid. From the correlation between the ratio of the areas of the bands at 1672 cm−1 and 1648 cm−1, characteristic of weakly intermolecularly hydrogen-bonded nitric acid and nitric acid strongly bonded to TBP, respectively, the molecular HNO3 concentration was determined. The presence of these two bands in the spectra of the third phase samples provides evidence that only part of the HNO3 is directly and strongly bound to the TBP phosphoryl group. The ratio of the weakly intermolecularly hydrogen-bonded HNO3 to that bound directly to P=O group of TBP was much higher for the uranium than for the thorium third phases formed under comparable conditions. The estimated amounts of the weakly intermolecularly hydrogen-bonded HNO3 were about 47% and 30% of the ...

FT-IR STUDY OF THIRD PHASE FORMATION IN THE U(VI) OR Th(IV)/HNO3, TBP/ALKANE SYSTEMS

The changes in the structure of sabugalite have been undertaken using thermo-Raman and infrared spectroscopy based upon the results of thermogravimetric analysis. Two Raman bands are observed at 835 and 830 cm -1 assigned to the (UO2) 2+ stretching vibrations resulting from the non-equivalence of the uranyl bonds (UO2) 2+ . These bands give calculated U-O bond lengths of 1.773 and 1.7808 A. A low intensity band is observed at 895 cm -1 assigned to the ν3 antisymmetric stretching vibration of (UO2) 2+ units. Five bands are observed in the 950 to 1050 cm -1 region in the Raman spectrum of sabugalite and are assigned to the ν3 antisymmetric stretching vibration of (PO4) 3- units. Changes in the Raman spectra reflect changes in the structure of sabugalite as dehydration occurs. No (PO4) 3- symmetric stretching mode is observed. This result is attributed to the non-equivalence of the PO bonds in the PO4 units. The PO4 vibrations were not affected by dehydration. Thermo-Raman spectroscopy proved to be a very powerful technique for the study of the changes in the structure of sabugalite during dehydration.

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Thermo‐Raman spectroscopic study of the uranium mineral sabugalite

Formation and crystal and molecular structures of dioxouranium(VI) complexes containing bidentate carbamoylmethylphosphinate and phosphine oxide ligands

Carbon nanotubes (CNTs) were synthesized by the floating catalytic chemical vapor deposition technique using ferrocene in benzene as the hydrocarbon source. The functionalization of CNTs was carried out by oxidation (CNT-OX) and grafting with a tributyl phosphate (TBP) ligand (CNT-TBP). Various spectroscopic techniques including scanning electron microscopy (SEM), Fourier Transform Infra Red Spectroscopy (FTIR), BET surface area and X-ray photoelectron spectroscopy (XPS) were used to characterize the adsorbents. FTIR and XPS studies revealed the efficient grafting of the TBP ligand on the CNT surface. The effect of the initial pH and the contact time for the maximum adsorption of U(VI) with CNT-plain, CNT-OX and CNT-TBP was studied. The spontaneity of the sorption was confirmed by thermodynamic data. A pseudo second order model with a regression coefficient of >0.978 was obtained for CNT-TBP and equilibrium was reached within 3 h. The Langmuir maximum adsorption capacity of U(VI) at pH 5 for CNT, CNT-OX and CNT-TBP was found to be 66.6, 100.0 and 166.6 mg g−1 respectively. Using 0.1 M HCL as a desorbent, recyclability studies were carried out for three cycles. The probable mechanism of adsorption between U(VI) and CNT-TBP could be understood through FTIR and XPS techniques.

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The synthesis and characterization of tributyl phosphate grafted carbon nanotubes by the floating catalytic chemical vapor deposition method and their sorption behavior towards uranium

M.W. Wakerley

Papers

Infrared and Raman spectra of the uranyl ion