The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform
P. V. Ravindran - One of the best experts on this subject based on the ideXlab platform.
-
Room temperature reaction between Uranyl Nitrate hexahydrate and rubidium Nitrate and polymerisation during denitration of rubidium Uranyl Nitrate at elevated temperatures
Thermochimica Acta, 2010Co-Authors: Bhupesh B. Kalekar, K. V. Rajagopalan, P. V. RavindranAbstract:Abstract The interaction between Uranyl Nitrate hexahydrate (UNH) and rubidium Nitrate in solid state at elevated temperatures has been studied for several compositions using simultaneous thermal analysis techniques (TG–DTA–EGA), X-ray diffraction and IR spectral measurements. The formation of rubidium Uranyl Nitrate has been observed in rubidium Nitrate rich mixtures even at ambient temperature during mixing of the two Nitrates in solid state. The reaction at room temperature was incomplete in mixtures containing higher than 30 mol% Uranyl Nitrate hexahydrate. Thermal and XRD data on equimolar mixture indicate complete dehydration of Uranyl Nitrate hexahydrate by 300 °C to form rubidium Uranyl Nitrate, Rb[UO 2 (NO 3 ) 3 ], which decomposes on further heating to the polymerised structures, Rb 2 [(UO 2 NO 3 ) 2 (O) 2 ] and Rb 4 [(UO 2 ) 3 (O) 4 (NO 3 ) 2 ] above 360 °C and 460 °C, respectively. Rb 4 [(UO 2 ) 3 (O) 4 (NO 3 ) 2 ] reacts with UO 3 above 550 °C to form rubidium diuranate, Rb 2 U 2 O 7 , when the initial Nitrate mixture is prepared from compositions containing UNH at 50 mol% or lower levels. In the case of initial Nitrate mixtures containing a higher amount of UNH, however, Rb 2 U 4 O 13 and U 3 O 8 are formed above 550 °C.
-
Thermal decomposition of Uranyl Nitrate hexahydrate
Journal of Thermal Analysis, 1995Co-Authors: K. V. Rajagopalan, P. V. Ravindran, T. P. RadhakrishnanAbstract:TG-DTA-EGA studies have shown that anhydrous Uranyl Nitrate cannot be obtained by thermal decomposition of Uranyl Nitrate hexahydrate. Hydrolysis and polymerization of the salt during dehydration resulted in hydroxyNitrates which decomposed in multiple steps with the evolution of oxides of nitrogen and water. The extent of hydrolysis dependend on the sample size, heating rate and nature of sample containment. Large samples on decomposition at relatively high heating rates showed evolution of nitric oxide even above 500°C. Infrared studies on the residues prepared at various temperatures supported the conclusions.
Olivier Bernard - One of the best experts on this subject based on the ideXlab platform.
-
Description of partition equilibria for Uranyl Nitrate, nitric acid and water extracted by tributyl phosphate in dodecane
Hydrometallurgy, 2011Co-Authors: S. P. Hlushak, Jean-pierre Simonin, Barbara Caniffi, Philippe Moisy, Christian Sorel, Olivier BernardAbstract:Abstract Experiments were carried out on the partitioning of Uranyl Nitrate in nitric acid solution extracted by 30 vol.% of tributyl phosphate (TBP) in dodecane at 25 °C. The model proposed by Naganawa and Tachimori (Bull. Chem. Soc. Jap. 70, 809, (1997)) for the case of aqueous solutions of nitric acid was used to additionally describe the extraction equilibria of Uranyl Nitrate. The treatment is based on the assumption of thermodynamic ideality for the organic solution composed of the diluent, the free extractant and the complexes. The stoichiometries of the metal complexes were determined one by one by a suitable procedure. The formation of 6 different complexes involving Uranyl Nitrate was found capable of representing the partition equilibria for the three extracted compounds: nitric acid, water and Uranyl Nitrate. This approach suggests the formation of 2:1 and 3:1 complexes for TBP and Uranyl Nitrate, respectively.
Geraldo Vicentini - One of the best experts on this subject based on the ideXlab platform.
-
Uranyl Nitrate complexes with lactams
Journal of Alloys and Compounds, 2001Co-Authors: A.r De Aquino, Paulo Celso Isolani, Julio Zukerman-schpector, Léa Barbieri Zinner, Geraldo VicentiniAbstract:Abstract The preparation, characterization and spectroscopy of complexes of Uranyl Nitrate with the lactams: δ-valerolactam (δ-val, C 5 H 9 NO), e-caprolactam (e-capro, C 6 H 11 NO), 2-azacyclononanone (2-aza, C 8 H 15 NO) and 2-azacyclotridecanone (2-actd, C 12 H 23 NO) are described. They were prepared by reaction of hydrated Uranyl Nitrate with the ligands in ethanolic solution (molar ratio 1:2) and presented the general composition UO 2 (NO 3 ) 2 .2L, except for the e-capro complex that is dimeric, with composition: (UO 2 ) 2 (NO 3 ) 2 (O 2 )(e-capro) 4 . The peroxo bridge was introduced when 2,2-dimethoxypropane contaminated with peroxide was used to precipitate the crystals. They were characterized by CHN microanalyses, IR spectra, TG and DSC analyses and emission spectra in the visible region. The structure of the e-capro complex was determined by X-ray single crystal analysis.
R J Nesbitt - One of the best experts on this subject based on the ideXlab platform.
-
thermal decomposition of Uranyl Nitrate hexahydrate
Journal of Chemical Technology & Biotechnology, 2007Co-Authors: S Hartland, R J NesbittAbstract:Samples of Uranyl Nitrate hexahydrate weighing between 3·5 and 14·7 mg. were decomposed in a hot air stream flowing at 455–673 cm./sec. and at temperatures between 100 and 350°. Values of percentage weight-loss for various reaction times were obtained. The decomposition, which involved several phase changes, was also followed visually by means of a colour cine film. The results between 200° and 350° suggest that decomposition proceeds by way of two first-order reactions: and where k1 is much greater than k2. These results do not agree with those of previous workers who used larger samples and lower gas flow rates and did not work in a purely chemical regime.
Michael G. B. Drew - One of the best experts on this subject based on the ideXlab platform.
-
Synthesis and structural studies of a bis(carbamoyl methyl) sulfoxide complex of Uranyl Nitrate
Journal of Coordination Chemistry, 2010Co-Authors: Sadhan Bijoy Deb, Shanmugaperumal Kannan, Michael G. B. DrewAbstract:A new tri-functional ligand iBu2NCOCH2SOCH2CONiBu2 was prepared and characterized. The coordination chemistry of this ligand with Uranyl Nitrate was studied with IR, 1H NMR, electrospray mass–spectrometry, thermogravimetry, and elemental analysis. The structure of [UO2(NO3)2(iBu2NCOCH2SOCH2CONiBu2)] was determined by single-crystal X-ray diffraction. The uranium(VI) ion is surrounded by eight oxygens in a hexagonal bipyramidal geometry. Four oxygens from two Nitrates and two oxygens from the ligand form a planar hexagon. The ligand is a bidentate chelate, bonding through sulfoxo and one of the carbamoyl groups to Uranyl Nitrate.
