Authors:S. Hasilkar, Keshav Chander, and S. Marathe
Attempts to carry out potentiometric determination of plutonium (by AgO-oxidation method) following the determination of thorium (by complexometric EDTA titration) gave positively biased irreproducible values of plutonium. In order to understand the factors leading to the erroneous values of plutonium, the effect of varying amounts of AgO and EDTA on redox [Fe(II)/K2Cr2O7] titration in the medium consisting of 1M H2SO4 and 0,4M HNO3 was studied. When AgO (up to 200 mg) was added in the titration medium and destroyed by sulfamic acid prior to the redox titration, the dichromate tittre value (amount of standard K2Cr2O7 solution equivalent to 1 g of Fe(II) solution) showed negative bias. The bias was found to decrease with increase in time interval between AgO destruction and the redox titration. The presence of EDTA (up to 15 mg) gave positive bias in the titre value. Results on the titre values obtained under different conditions of the aqueous medium indicated the possibility of formation of unstable Ag(II)-sulfamic acid compled, which is probably responsible for the irreproducible values of plutonium.
Authors:Keshav Chander, S. Hasilkar, and S. Marathe
A method for the sequential determination of thorium and plutonium has been developed. In the sample solution containing thorium and plutonium, thorium is first determined by complexometric titration with EDTA and then in the same solution plutonium is determined by redox titration employing potentiometry. Prior to the determination of plutonium, EDTA is destroyed by fuming with concentrated HClO4. Thorium is determined at 10 mg level and plutonium at 1 mg level with precision and accuracy of better than ±0.5%.
In the first part of the paper, we had presented data on simulated conditions favorable for the separation of molybdenum from uranium under conditions existing in irradiated uranium. As mentioned, the aim of this study is the adoption of a method for the routine extraction of 99Mo (fission molybdenum) from the large bulk of uranium and host of radionuclides, additional parameters need to be evaluated to arrive at an effective procedure. This paper deals with the further purification of 99Mo obtained using differential volatility of their chlorides to a quality meeting the requirements of pharmaceutical standards.
Among the separation methods of molybdenum from uranium, the difference in volatility of their chlorides at relatively high temperatures could also be conveniently exploited. This concept is adopted to have a standardization of a method for providing abundant quantity, with a high chemical purity of 99Mo, which is an important radioisotope used in the nuclear medicine. The approach to the standardization consists of identifying the necessary parameters to work at high temperatures and efficient collection of molybdenum. These operations are designed to be carried out in a well ventilated lead-shielded plant with remote facilities.
Authors:S. Hasilkar, N. Gopinath, Keshav Chander, S. Marathe, and H. Jain
A method based on the complexometric titration of thorium using ethylene diaminetetra-acetic acid (EDTA) as complexant has been developed for the determination of thorium in thorium-plutonium solution without resorting to prior separation of plutonium. Plutonium in the form of Pu(VI) does not affect the thorium determination when present up to 10% in thorium—plutonium solution. For oxidation of plutonium to Pu(VI), HClO4 or AgO was used. HClO4 is preferred. The thorium values obtained without prior separation of plutonium are compared with those obtained after separating plutonium by anion exchange technique. A precision of ±0.5% has been obtained for 5–10 mg of thorium in the aliquot.
Authors:Keshav Chander, S. Hasilkar, A. Jadhav, and H. Jain
A method for the sequential determination of thorium and uranium has been developed. In the sample solution containing thorium and uranium, thorium is first determined by complexometric titration with ethylenediaminetetraacetic acid (EDTA) and then in the same solution uranium is determined by redox titration employing potentiometry. As EDTA interferes in uranium determination giving positive bias, it is destroyed by fuming with HClO4 prior to the determination of uranium. A precision and accuracy of better than ±0.15% is obtained for thorium at 10mg level and uranium ranging from 5 mg to 20 mg in the aliquot.
Authors:S. Hasilkar, N. Khedekar, Keshav Chander, A. Jadhav, and H. Jain
Studies have been carried out on the solubility of Pu(III) oxalate by precipitation of Pu(III) oxalate from varying concentrations of HNO3/HCl (0.5–2.0M) solutions and also by equilibrating freshly prepared Pu(III) oxalate with solutions containing varying concentrations of HNO3/HCl, oxalic acid and ascorbic acid. Pu(III) solutions in HNO3 and HCl media were prepared by reduction of Pu(IV) with ascorbic acid. 0.01–0.10M ascorbic acid concentration in the aqueous solution was maintained as holding reductant. The solubility of Pu(III) oxalate was found to be a minimum in 0.5M–1M HNO3/HCl solutions containing 0.05M ascorbic acid and 0.2M excess oxalic acid in the supernatant.