The chemical effects of56Mn-recoils following neutron capture produced in mixed crystals /KMnO4–LiClO4, KMnO4–NaClO4 and KMnO4–KClO4/ have been investigated. A linear increase of initial retention with the mol fraction of perchlorate was observed which is tentatively ascribed to the tendency to form species having structures similar to that of the host matrix. The ultimate chemical fate of the manganese atom also depends on the conditions of the immediate chemical environment of the atoms /e.g. Li, Na, K/ at rest in the crystal. The results are discussed in terms of retention and non-retention reactions invoking a mechanistic model involving metal and ligand-vacancy exchange, substitution and transfer reactions.
Authors:Devendra Singh, J. Singh, O. Singh, and S. Tandon
Extraction of zinc(II) and cadmium(II) from ammonium thiocyanate solutions has been studied in benzene in the presence of
pyridine. The effect of such variables as the pH of aqueous phase and concentration of metal, thiocyanate and pyridine on
extraction has been investigated and the extracting species identified. Extraction behaviour of silver(I), manganese(II),
cobalt(II), mercury(II) and thallium(III) has also been studied under identical conditions and some binary metal ion separations
of analytical and radiochemical importance are reported.
Authors:S. Dogmane, R. Singh, D. Bajpai, and J. Mathur
Extraction of U(VI) from HNO3, HCl and HClO4 media using cyanex-272 (bis[2,4,4 trimethyl pentyl] phosphinic acid)/n-dodecane has been carried out. In the case of HNO3 and HClO4 media, the distribution ratio (D) value first decreases and then increases, whereas from HCl medium it first decreases and then remains constant with increase in H+ ion concentration. At lower acidities, U(VI) was extracted as UO2(HA2)2 by an ion exchange mechanism, whereas at higher acidities as UO2(NO3)2.2(H2A2) following a solvation mechanism. The D for U(VI) by cyanex-272, PC-88A and DEHPA at low acidities follows the order cyanex-272 > PC-88A > DEHPA. Also, cyanex-272 was found to extract U(VI) more efficiently than TBP at 2M HNO3. The effect of diluents on the extraction of U(VI) by cyanex-272 followed the order cyclohexane > n-dodecane > CCl4 > benzene. The loading of U(VI) into cyanex-272/n-dodecane from 2M HNO3 has shown that at saturation point, cyanex-272 was 78% loaded. No third phase was observed at the saturation level. The stripping of U(VI) from the loaded organic phase was not possible with water, it was poor with acetic acid and sodium acetate but quantitative with oxalic acid, ammonium carbonate and sodium carbonate.
Authors:S. Salunke, Kulwant Singh, A. Bidaye, and J. Goswami
Partitioning of plutonium from uranium is an important step in the reprocessing of spent fuel by PUREX process of solvent
extraction using 30% TBP-dodecane. This is achieved by selectively reducing the Pu in solution to least extractable trivalent
state by uranous nitrate as the reductant. The latter is conventionally produced by electrolytic reduction of uranyl ion in
presence of hydrazine nitrate as uranous nitrate stabilizer using Pt-coated titanium as the anode. The anode plating wears
out after period of operation thus affecting the process efficiency and hence the quality control testing of platinum plated
electrode becomes important. This article describes the use of Beta backscattering method with strontium-90 radioisotope as
non-destructive testing tool for measuring the coating thickness of the sample Ti electrode. The surface characteristics and
coating morphology were also examined by scanning electron microscope and the micrographs are presented.
Authors:Sujoy Biswas, D. Singh, K. Hareendran, J. Sharma, and S. Roy
Solvent extraction of U(VI) with di-isodecyl phosphoric acid (DIDPA)/dodecane from nitric acid medium has been investigated
for a wide range of experimental conditions. Effect of various parameters including nitric acid concentration, DIDPA concentration,
temperature, stripping agents, and other impurities like rear earths, transition metal ion, boron, aluminum ion on U(VI) extraction
has been studied. The species extracted in the organic phase is found to be UO2(NO3)(HA2)·H2A2 at lower acidity (<3.0 M HNO3). Increase in temperature lead to the decrease in extraction with the enthalpy change by ∆H = −16.27 kJ/mol. Enhancement in extraction of U(VI) from nitric acid medium was observed with the mixture of DIDPA and tri
butyl phosphate (TBP). The stripping of U(VI) from organic phase (DIDPA–U(VI)/dodecane) with various reagents followed the
order: 4 M H2SO4 > 5% (NH4)2CO3 > 8 M HCl > 8 M HNO3 > Water. High separation factors between U(VI) and impurities suggested that the use of DIDPA for purification of uranium
from multi elements bearing solution.
Authors:Sujoy Biswas, K. Hareendran, D. Singh, J. Sharma, and S. Roy
Extraction behavior of U(VI) and Th(IV) from nitric acid medium is investigated using organo-phosphorous extractant, tri(butoxyethyl)
phosphate in n-paraffin at room temperature (27 ± 1 °C). The effect of diluents, nitric acid concentration as well as extractant concentration
on extraction of U(VI) and Th(IV) are evaluated. Extraction of U(VI) and Th(IV) from nitric acid medium proceeds via solvation
mechanism. Slope analysis technique showed the formation of neutral complexes of the type of UO2(NO3)2·2TBEP and Th(NO3)4·3TBEP with U(VI) and Th(IV) respectively in the organic phase. The FTIR data showed shifting of P=O stretching frequency
from 1,282 to 1,217 cm−1 indicating the strong complexation of P=O group with UO22+ ions in the organic phase. Effect of stripping agents, other metal ions and their separation with respect to U(VI) extraction
has also been investigated.
Authors:M. Alrakabi, G. Singh, A. Bhalla, S. Kumar, S. Kumar, A. Srivastava, B. Rai, N. Singh, J. Shahi, and D. Mehta
The elemental concentration of uranium in the samples collected from the ground water and the canal water in the Bathinda
district of Punjab state, India, have been investigated using X-ray fluorescence technique. The residues obtained after drying
the water samples were analysed using the energy dispersive X-ray fluorescence spectrometer consisting of Mo-anode X-ray tube
equipped with selective absorbers as an excitation source and an Si(Li) detector. The uranium concentration values in significant
fraction of the shallow ground water samples from the hand pumps is found to be above the permissible level of 15 ppb recommended
by World Health Organisation for the drinking water, and its values in the canal water samples are below 5 ppb. To investigate
the flyash from the coal-fired thermal power plants as a possible source of ground water contamination, the water samples
collected from the surroundings of the power plants and the flyash samples were also analyzed. The results rule out flyash
as a source of uranium contamination. Agrochemical processes occurring in the calcareous soils in the region are the favoured
potential source of uranium contamination of the ground water.
Authors:R. Parveen, F. J. Ahmad, Z. Iqbal, M. Singh, Y. T. Kamal, and S. Ahmad
Andrographolide and betulinic acid are the terpenoids having potential anti-cancer activity. The cytotoxicity activity of both the drugs was carried out separately and in combination on liver cancer HepG2 cell lines. High-performance liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) methods were developed and validated for simultaneous estimation of these two terpenoids as per the International Conference on Harmonization (ICH) guidelines, which was applied for quantification in nanoformulation. The retention time by HPLC and retardation factor by HPTLC for andrographolide and betulinic acid were found to be 2.2 and 6.6 min, and 0.24 ± 0.01 and 0.66 ± 0.01, respectively. Both the methods were validated for accuracy, precision, repeatability, robustness, limit of detection (LOD), and limit of quantitation (LOQ). The content of andrographolide and betulinic acid in nanoformulation was found to be 96.0% and 98.0% by HPLC and 96.59% and 98.33% by HPTLC, respectively, of labelled claim.
Authors:K. Pramod, U. K. Ilyas, M. Singh, Y. T. Kamal, S. Ahmad, S. H. Ansari, and J. Ali
High-performance thin-layer chromatography (HPTLC) method for the quantification of eugenol from nanostructured drug delivery systems was successfully developed and validated. The mobile phase consisted of n-hexane:acetone (7:3, v/v), and the densitometric scanning was performed in the absorbance mode at 280 nm. The method was valid with respect to linearity and range, accuracy, precision, specificity, detection limit (DL), and quantitation limit (QL). The linearity of the method was established by a correlation coefficient value of 0.9930 ± 0.0013. The precision was tested by checking intra-day (repeatability) and inter-day (intermediate precision) variations. The method was established to be precise by low relative standard deviation (RSD) values for different concentration of eugenol. The results of the recovery studies of eugenol from preanalyzed samples demonstrated the accuracy of the method. The specificity of the developed method for the analysis of eugenol in the nanoemulsion gel and nanoparticles samples was confirmed by comparing the spectra obtained in standard and sample analysis. The DL and QL were determined to be 31.41 and 95.17 ng band−1, respectively, for the HPTLC method. The forced degradation studies revealed on eugenol established the effectiveness of the developed and validated method. The developed and validated HPTLC method was found to be a stability-indicating one, as indicated by the results of forced degradation studies, for its use during the accelerated stability studies of the nanoemulsion gels and nanoparticles of eugenol.
Authors:Y. Gautam, A. Sharma, S. Sharma, K. Rao, J. Kumar, V. Kumar, B. Singh, A. Kumar, and A. Hedge
Atmospheric tritium activity is measured regularly around Narora Atomic Power Station (NAPS) since gaseous waste, which contains
tritium, is being released through a 145 m high stack at NAPS site. Atmospheric data collected during 2004–2008 shows a large
variation of 3H concentration in air, fluctuating in the range of ≤0.2–91.6 Bq m−3. Significantly, higher tritium levels were measured in samples near the site boundary (1.6 km) of NAPS compared to off-site
locations. The atmospheric dilution factor was found to be in the range of 1.1 × 10−7–7.3 × 10−7 s m−3. The scavenging ratio of NAPS site was found to be varying from 0.2 × 104 to 14.1 × 104 (Bq m−3 rain water per Bq m−3 air). The inhalation dose to a member of general public at different distances (1.6–30 km) from NAPS site was found to be
ranged from 0.08–0.21 μSv year−1.