Authors:M. Jose John, K. Muraleedharan, V. M. Abdul Mujeeb, M. P. Kannan, and T. Ganga Devi
starting material for versatile industries, it is very important to determine the thermal decomposition mechanism, kinetics and thermodynamic parameters of sodiumoxalate for advantages in cost and time management for industrial production. Although there
sodium niobate (NaNbO 3 ) powders [ 12 ]. The use of Na 2 C 2 O 4 as starting material (instead of Na 2 CO 3 ) resulted in a low-temperature solid-state reaction. In general, the sodiumoxalate, Na 2 C 2 O 4 , serves as a metal cleaning preparation in
Authors:W. Balcerowiak, J. Wasilewski, and Cz. Latocha
The ternary system containing H2C2O4 · 2H2O, NaHC2O4 · and Na2C2O4 was investigated. It was ascertained that the termal curves of the mixtures were not the algebraic sums of their component curves. All thermal decomposition stages were interpreted and the means of performing qualitative and quantitative analyses in the system were given.
On the basis of uniform methodics, oxalatometallates of rare earths(III) with sodium, were synthesized. The compounds were obtained by adding saturated solution of sodium oxalate to 1 M solutions of Ln(NO3)3 in a molar ratio Na2C2O4/Ln3+ not lower than 5. X-ray powder diffraction photographs were used for the classification of the isolated compounds into five, internally isostructural groups.
Authors:A. Illaszewicz, K. Müller, D. Rabussay, and H. Spitzy
A new analytical method using metallic silver (110mAg) as radioreagent is reported. A known amount of excess oxidant is applied to the reducing agent which is to be determined.
After the reaction has taken place, the excess of the oxidizing agent is reacted with the neutron-activated silver whereby110mAg ions are released. The count rate of the solution is proportional to the excess of the oxidant, thus it is possible to
determine the original content of the reducing agent in question. The proposed redox procedure based on back measurements
has been applied to determinations of hydrogen peroxide, sodium oxalate, potassium ferrocyanide(II), uranium(IV), as well
as hydroquinone and ethanol in the μg range. The method makes use of calibration curves; the standard deviation is ±2% on
the average. Necessary heights of the normal potentials of the involved systems, favourable reaction conditions, and kineticsa
Authors:Li Lin, Yang Yan-Zhao, Zeng Shan, Zhu Tao, and Sun Si-Xiu
The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP)
and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid,
sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change
for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol
and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar
ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO2(NO3)2 . BDSO . TBP.
Studies on adsorption behavior of heavy radionuclides, present altogether in no-carrier-added state, e.g., 197-200Pb, 197-200Tl and 197Hg, have been carried out with calcium alginate beads. High lead (100%) and moderate thallium removal (~65%) was achieved
in pH range 2-7. 100% mercury removal was also achieved at pH 2 and 4. Effort has been made to recover all three radionuclides
adsorbed in the calcium alginate beads using various chemicals, such as HCl, thiourea, sodium acetate, sodium oxalate and
sodium nitrite. It was found that 0.1M HCl and 0.1M thiourea could remove at pH 1 80-90% of adsorbed Pb. Tl recovery was possible
by all chemicals mentioned above. Hg was also recovered by all chemicals except HCl.
The thermal investigation of the reaction taking place between dichromates and oxalates in the solid state has been done taking two systems of potassium dichromate-potassium oxalate and sodium dichromate-sodium oxalate. The techniques employed include thermogravimetry, differential thermal analysis, infrared spectroscopy and X-ray diffraction studies. The results indicate a stoichiometric reaction of dichromate and oxalate in 1∶1 ratio to give the corresponding chromate as the sole product.
Authors:M. Charyulu, D. Phal, D. Noronha, V. Ramakrishna, and V. Venugopal
The extraction of Am(III) from nitric, hydrochloric, oxalic, phosphoric and hydrofluoric acids was studied using 0.4F di-2-ethyl hexyl phosphoric acid (HDEHP) containing 0.1M phosphorous pentoxide (P2O5) in dodecane/xylene. The extraction with pure 0.4F HDEHP was found to be negligible from all the media studied. However, the presence of a small amount of P2O5 in it increased the extraction substantially. The distribution ratios of Am(III) obtained for HDEHP - P2O5 mixture 3M nitric acid containing different concentrations of oxalic acid/phosphoric acid/hydrofluoric acid are in the order of 200-250. The same for 3M hydrochloric acid is very high (800). These distribution ratios are sufficiently high for the quantitative extraction of Am(III) from all the acid media studied. Different reagents such as ammonium oxalate, sodium oxalate, oxalic acid, hydrofluoric acid, sodium carbonate and potassium sulphate were explored for the back extraction of Am(III) from 0.4F HDEHP + 0.1M P2O5 in dodecane/xylene. Of these, 0.35M ammonium oxalate and 1M sodium carbonate were found to be most suitable. The back extraction of Am(III) was also attempted with water and 1M H2SO4, HNO3, HClO4 and HCl solutions after allowing the extracted organics to degrade on its own. It was found that more than 90% of Am could be back extracted with these acids. Using this method more than 90% of Am(III) was recovered from nitric acid solutions containing calcium and fluoride ions.