http://nopr.niscair.res.in/handle/123456789/2201 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/2227 Title: A rapid spectrophotometric method for the determination of molybdenum using ferron in industrial and environmental samples <br/> <br/>Authors: Kumar, Anil; Dass, Rameshwar <br/> <br/>Abstract: Ferron has been used as an analytical reagent for the extractive spectrophotometric determination of molybdenum(V) obtained from the reduction of molybdenum(VI) with ascorbic acid. Molybdenum(V) in presence of a large number of cations, anions and complexing agents forms a yellow complex with ferron that is quantitatively extractable into tri-n-octylamine-chloroform from 1 M H₂SO₄ medium. The complex is stable for at least 24 h and shows an absorption maximum at 425 nm with molar absorptivity and Sandell’s sensitivity of 3.96×10³ l mol⁻¹ cm⁻¹ and 0.02525 μg cm⁻² Mo(V), respectively. The method obeys Beer’s law up to 31 μg ml⁻¹ Mo(V). For ten replicate determinations of 10 μg ml⁻¹ Mo(V), the relative standard deviation is found to be 0.54%. The method is simple, selective, precise and rapid, and has been satisfactorily applied to the determination of molybdenum in aqueous, synthetic and technical samples of diverse matrices. <br/> <br/>Page(s): 1533-1536 Sun, 28 Sep 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2226 Title: Solid phase extraction of cerium(IV) with crosslinked poly(acrylic acid) coated on silica gel <br/> <br/>Authors: Chowdhury, Pranesh; Pandit, Susanta K; Mandal, Bhabatosh <br/> <br/>Abstract: A selective method has been developed for extraction and separation of Ce(IV) with the high molecular mass crosslinked poly(acrylic acid), coated on silanized silica gel. The coated materials act as stationary phase for the extraction. The structure and thermal stability of crosslinked poy(acrylic acid) has been elucidated with the help of FTIR and TGA. Ion exchange and breakthrough capacity of the exchanger have been measured. Surface morphology of the exchanger has been studied by SEM. Ce(IV) has been separated quantitatively from various synthetic mixtures containing metal ions commonly present in thorium and uranium ores, minerals and fission products. The developed method has been tested for some real samples. A plausible mechanism for Ce(IV) extraction and elution has been suggested. <br/> <br/>Page(s): 1528-1532 Sun, 28 Sep 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2225 Title: Effect of inorganic ions on surface properties of a non-ionic surfactant at various temperatures in aqueous medium <br/> <br/>Authors: Partap, Ram; Yadav, O P <br/> <br/>Abstract: Studies on surface tension of iso-octyl phenoxy polyethoxy ethanol in water and in the presence of aqueous Na₂SO₄ and Na₃PO₄ salts having varying anion valency at 288, 293 and 298 K are reported. The values of critical micelle concentration, maximum surface excess concentration and minimum area per molecule of the surfactant at air-liquid interface have been evaluated. Thermodynamic parameters of micellization and those of adsorption have also been evaluated. The micellization process appears to be endothermic in nature while negative values of ΔG⁰m and positive values of ΔS⁰m support its spontaneity. <br/> <br/>Page(s): 1524-1527 Sun, 28 Sep 2008 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/2222 Title: Kinetics and mechanism of oxidation of some thioacids by benzyltrimethylammonium chlorobromate <br/> <br/>Authors: Tiwari, Vandana; Kumbhani, S; Shastri, I; Sharma, Vinita <br/> <br/>Abstract: The oxidation of some thioacids, viz., thioglycollic, thiolactic and thiomalic acids by benzyltrimethylammonium chlorobromate (BTMACB) has been studied in acetic acid. The reaction is first order with respect to BTMACB. Michaelis Menten type of kinetics have been observed with respect to the reductants. The reaction has been studied in solvents of different compositions of acetic acid and water. The solvent composition effect has been analysed using Grunwald-Weinstein equation. A mechanism involving the formation of an intermediate complex in the pre-equilibrium and its subsequent decomposition in slow step has been proposed. <br/> <br/>Page(s): 1520-1523 Sun, 28 Sep 2008 22:58:59 GMT