NOPR Collection:

Preparation and some properties of lithium vanadium bronzes

2016-07-20T06:45:49Z

Title: Preparation and some properties of lithium vanadium bronzes Authors: EI-Sayed, AM; Mousa, S M A Abstract: Lithium vanadium bronzes with composition formula Li_x V₂O₅ (0.04 ≤ x ≥ 0.92) have been prepared by solid-state reaction at 650°C in argon atmosphere. The products were characterized by X-ray powder diffraction and IR spectroscopy. The results reveal that four phases namely α-, β-, βʹ- and γ-phase are present in the studied range. The magnetic susceptibility for the investigated samples was measured using Gouy’s method. The values of the effective magnetic moments as calculated from experimental data indicate the presence of V⁴⁺ ions in all samples. The electrical conductivity as a function of temperature and lithium content was measured in the temperature range from-room temperature to 483 K. The electrical conductivity of the samples is found to be affected by lithium content. The values of the electrical conductivity increase with temperature for the investigated samples. The electronic and ionic conductions are discussed. Page(s): 372-377

Study on defluoridation of drinking water by impregnation of metal ions in activated charcoal

2010-01-06T16:30:31Z

Title: Study on defluoridation of drinking water by impregnation of metal ions in activated charcoal Authors: Janardhana, C; Rao, G Nageswara; Sathish, R Sai; Lakshman, V Sai Abstract: Defluoridation of drinking water was carried out by the continuous down flow adsorption mode at room temperature. Five columns were prepared by the impregnation of ZrOCl₂, CaO, Alum, CaCl₂ and Borax in activated coconut shell charcoal. Known fluoride influent water was run into the column at a constant rate of 4.0 L/h and a constant level of water was maintained. Samples of the treated water were collected for analysis by the ion selective electrode method. In this study zirconium ion impregnated coconut shell charcoal (ZICSC) showed maximum fluoride uptake and proved to be the most effective defluoridating agent followed by CaO and Alum. Page(s): 414-416

Cetyldimethyl benzyl ammonium cerium nitrate as a phase-transfer oxidant in the oxidation of alcohols to carbonyl compounds

2010-01-05T16:30:31Z

Title: Cetyldimethyl benzyl ammonium cerium nitrate as a phase-transfer oxidant in the oxidation of alcohols to carbonyl compounds Authors: Baruah, Smriti Rekha; Kakati, Dilip Kumar Abstract: Oxidation of organic substrates by inorganic reagents is restricted by mutual insolubility of the two. However, this problem of mutual insolubility can be alleviated by the use of oxidants in the form of phase transfer reagents, like tetra-alkylammonium salts. Tetra-alkylammonium salt has a polar (N+) group and hydrocarbon side chains (alkyl groups). The ammonium salt allows a low concentration of oxidant to pass into the organic layer where they act as oxidizing agent. In the present case, the synthesis of a phase transfer oxidant cetyldimethyl benzyl ammonium cerium nitrate (CDBACN) and its use in the oxidation of alcohols to carbonyl compounds has been reported. CDBACN was synthesized from cetyldimethyl benzyl ammonium chloride (CDBACl) and ammonium ceric nitrate (CAN). The reagent was characterized by elemental analysis and spectral studies. The solubility and electronic spectra of the oxidant in various solvents were studied. This oxidant was successively utilized in the oxidation of different alcohols. Page(s): 411-413

Studies on yield improvement of High Melting Explosive (HMX)

2010-01-04T16:30:30Z

Title: Studies on yield improvement of High Melting Explosive (HMX) Authors: Das, S; Raut, V D; Gawande, N M; Khopade, R S; Narasimhan, V L Abstract: In India, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine, commonly known as HMX (High Melting Explosive), is manufactured by the modified Bachmann combination method using continuous nitrolysis of hexamine in a cascade of four stirred tank reactors. In this laboratory, the technology was established more than three decades ago with an overall yield of about 40%. However, as the reported yield of HMX is around 55%, it was considered essential to systematically study the Bachmann reaction system to improve the yield. As such a detailed study on quantities/ratios of raw materials and process conditions was carried out to improve the yield. Optimized ratios of raw materials, use of nitric acid having strength >99%, proper control of temperature and optimal nitration and residence time gave an yield of 60-65%. Page(s): 404-410