Aqueous chloramine-B /C6H5SO2NCl Na/ solution is known to contain species like RNCl–, RNHCl, RNCl2, RN+H2Cl, HOCl and H2+OCl where R=C6H5SO2. The exchange studies between36Cl and CAB carried out in various media by ion-exchange method indicated that there is no exchange in solution at pH7. As the pH is decreased below 7, the extent of exchange increases reaching a maximum at pH 3. 3. The exchange decreases as the acidity is increased between pH 3.3 and 1N and again the exchange increases beyong 1N. The observed increase in exchange in strong acid medium is due to the evolution of chlorine.
The exchange between chloramine-B and radioactive chlorine has been carried out in various media. The exchange is slow in strong acid and very weak acid media. Its maximum is at pH 3.3. There is no exchange in alkaline media. Optimum conditions for the preparation of radiochloramine-B with high specific activity are reported.
A new method for the continuous determination of H2O2 is described based on the catalytic decomposition of H2O2 by LaCoO3. Oxygen liberated is measured by a gas meauuring burette. -irradiated catalyst enhances the catalytic activity and decreases the time required for complete decomposition. The procedure is suitable for microdetermination of H2O2 in various food products.
Exchange studies with36Cl and Chloramine-B in strong acid medium revealed that the extent of exchange is less than that occurs at pH 3.3 indicating the formation of a new species of Chloramine-B which is not participating in the exchange reaction and this has been confirmed by conductometric titration of Chloramine-B with dilute solutions of H2SO4, HCl, HClO4 and CH3COOH.
Chemisorbed oxygen can be determined quantitatively by the measurement of gaseous N2/N2O liberated by treatment with hydrazine sulphate/hydroxylamine hydrochloride. The amount of chemisorbed oxygen depends on the degree of dispersion during irradiation and also the -dose. The chemisorption is enhanced in the presence of moisture. The partial reduction of the transition metal ion favours the formation of chemisorbed oxygen.
Volume reduction studies were carried out on low level radioactive plastic wastes containing polyethylene, PVC and neoprene
by melt densification. The optimized temperature for melting of plastics was between 170 and 180 °C. Based on laboratory scale
studies. Plant scale studies were planned and conducted. The volume reduction factors obtained were around 30, which was 6-10
times higher than that of the conventional compaction process. Thermogravimetry and infrared spectroscopy were used to investigate
the thermal and structural properties of the given materials. The effect of the presence of salts like potassium permanganate
and hydrazine sulphate on the thermal properties of the materials was also evaluated. Leaching studies were also performed
on melt-densified specimens in the laboratory. The average leach index was observed to be around 9, which was higher than
the minimum stipulated value.
Authors:Yeshwant Naik, G. Rama Rao, and V. Venugopal
The separation characteristics of hydrogen-tritium mixtures by gas chromatography at 77 K have been studied using molecular sieve 4A, coated with 5 wt% vanadium in the form of V2O4, as supporting material. The performance of the column was found to be better than that observed on the conventional coated and uncoated molecular sieves in terms of reduced retention times, resolution, nature of the peak and added thermal stability of the stationary phase.
Synergism is observed in the extraction of uranium(VI) by the binary mixture of Aliquat 336 and PC 88A (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) from 0.5–6M HNO3 solution showing a maximum at 3M. In H2SO4 medium, antagonism at lower acidity and slight synergism at higher acid concentrations have been observed. Synergism occurs in the extraction of Am(III) from nitrate solutions when a mixture of Aliquat 336 and TOPO is used.
Authors:V. Bhargava, V. Rao, S. Marathe, S. Sahakundu, and R. Iyer
A radiochemical method is described for the separation of heavier rare earths from the fission of uranium. The method is particularly
suitable for the separation of low yield (10−5%–10−7%), highly asymmetric rare earth fission products viz.179,177Lu,175Yb,173Tm,172,171Er,167Ho and161,160Tb in the neutron induced fission of natural and depleted uranium targets. Additional separation steps have been incorporated
for decontamination from239Np (an activation product) and93-90Y (a high fission-yield product) which show similar chemical behaviour to rare earths. Separation of individual rare earths
is achieved by a cation exchange method performed at 80°C by elution with α-hydroxyisobutyric acid (α-HIBA).
Authors:V. V. Deshpande, M. D. Karkhanavala, and U. R. K. Rao
It is shown that the heat of transition of the phase change II → I at 129° on heating KNO3 is dependent on the thermal history of the sample, since it involves two steps, viz., II→ III and III→ I at 2° interval. During cooling, the latter step is fast and truly reversible, though with a temperature hysteresis. The former step is sluggish and is dependent both on temperature and time. Our results indicate that KNO3 can be used for calibration purpose only if the material has not been heated beyond 128° in the immediately preceding three hours.