http://nopr.niscair.res.in/handle/123456789/10710 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/10721 Title: Determination of boron in zirconium-niobium alloys by spectrophotometry <br/> <br/>Authors: Ramanjaneyulu, P S; Sayi, Y S; Ramakumar, K L <br/> <br/>Abstract: Boron doped zirconium-niobium alloy rods are used as neutron reactivity control rods in advanced nuclear reactors. Accurate knowledge about the boron content in this alloy is an essential requirement prior to its usage in nuclear reactors. In view of the refractory nature of the alloy, boron determination in these type of matrices is a challenging task. Also due to non-availability of matrix matched reference materials, direct solid analysis cannot be resorted to. Quantitative dissolution of the matrix without losing any boron followed by its determination is the only alternative. In the present work, Zr-Nb sample was dissolved in (NH₄)₂SO₄ and H₂SO₄ taking care to prevent the loss of boron. Boron was selectively separated employing batch extraction with 10% 2-ethyl hexane 1,3 diol in chloroform and determined spectrophotometrically as B-Curcumin complex. Absorbance was measured at 550 nm. The precision and accuracy of the method is 3%. The absolute detection limit of the method is 12 ng. The method has been evaluated by standard addition method and validated by ICP-AES technique. <br/> <br/>Page(s): 468-470 Fri, 29 Oct 2010 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/10720 Title: Conductometric studies on solvation behaviour of citric acid in water + methanol and water + ethanol mixtures at different temperatures <br/> <br/>Authors: Bhat, J Ishwara; Manjunatha, M N <br/> <br/>Abstract: The paper reports the study on the effect of solvation of the species of citric acid in water + methanol and water + ethanol mixtures (<i style="">v/v</i>) on its conductivity behaviour as a function of temperature. The specific conductance was measured in the temperature range 283-313 K and the evaluated equivalent conductance was analyzed by Kraus-Bray and Shedlovsky models of conductivity. Limiting molar conductance (λ⁰_m), dissociation constant (<i style="">K</i>_C) and association constant (<i style="">K</i>_a) were evaluated for all solvent compositions. The limiting molar conductance was found to decrease with the increase in amount of co-solvent to water. <i style="">K</i>_c increased with increase in temperature till 60% methanol and 40% ethanol with a later decrease. Fuoss Accascina equation was applied and it was proved that the formation of ion pairs and scanty amount of ion triplets takes place in the system. Walden product, corrected Stokes radius (r_i), thermodynamic parameters and solvation number also have been evaluated. Born relation of solvation was verified. These data were used to study the nature of ion-solvent and solvent-solvent interactions existing in the system under prevailing conditions. <br/> <br/>Page(s): 462-467 Fri, 29 Oct 2010 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/10719 Title: Comminution behaviour of microwave heated two sulphide copper ores <br/> <br/>Authors: Kaya, Erol <br/> <br/>Abstract: The effect of microwave irradiation on the comminution of two sulphide copper ores with different mineralogy were investigated to enhance the milling processes. Each ore was subjected to microwave radiation for varying time periods to determine their heating profiles. Changes in breakage characteristics with the microwave exposure time were quantified by sieving breakage, standard Bond work index grindability and single particle drop weight comminution tests. The results of the sieving breakage tests with the untreated and microwaved samples indicated significant improvements in the size reduction due to microwave energy induced macro fracturing. Differing ore mineralogy has been shown to affect the effectiveness of microwave assisted size reduction. The results of the standard Bond work index grindability tests performed with both the microwave treated copper ores, on the other hand, suggested no significant improvements in grindability. The single particle fracture experiments performed with an Ultrafast Load Cell (UFLC) indicated similar results of no significant improvements in the fracture energies of the microwave treated ore samples. <br/> <br/>Page(s): 455-461 Fri, 29 Oct 2010 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/10718 Title: Oxidation of phenol using LaMnO₃ perovskite, TiO₂, H₂O₂and UV radiation <br/> <br/>Authors: Singh, Chandrakant; Rakesh, Meeta <br/> <br/>Abstract: LaMnO₃ perovskite has been used for the treatment of aqueous solution of phenol using stoichiometric amount of H₂O₂ and combination of TiO₂ and UV radiation. The oxidation of phenol was studied with [UV radiation]; [H₂O₂ and UV]; [TiO₂ and UV]; [LaMnO₃ and UV]; [TiO₂, H₂O₂ and UV]; [LaMnO₃, H₂O₂ and UV]; to establish the effectiveness of different systems when compared with perovskite catalyst. Results show that the phenol degradation efficiencies decreased in the following order [LaMnO₃, H₂O₂ and UV] &gt; [TiO₂, H₂O₂and UV] &gt; [LaMnO₃ and UV] &gt; [TiO₂ and UV]&gt; [H₂O₂ and UV ] &gt; [UV]. UV-VIS spectra result of phenol degradation shows that as the concentration of catalyst increases, its activity increases. The optimum concentration of catalyst was 0.60 g/L for 100 ppm phenol solution. Perovskite catalyst after reaction is completely regenerated by calcinations at 800°C for 2 h and retains a similar catalytic performance <br/> <br/>Page(s): 451-454 Fri, 29 Oct 2010 22:58:59 GMT