http://nopr.niscair.res.in/handle/123456789/9916 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/9924 Title: Photo-oxidative degradation of an azo dye direct red 31 in the presence of ZnS catalyst <br/> <br/>Authors: Rao, A Nageswara; Sivasankar, B; Sadasivam, V <br/> <br/>Abstract: The photocatalytic degradation of direct red 31 on irradiation with UV light in the presence of ZnS photocatalyst has been reported. Effect of <i style="">p</i>H, weight of catalyst and concentration of dye on the degradation has been studied. A higher removal of dye is observed under mildly acidic conditions. The optimum weight of catalyst loading is found to be 3.0 g/L. The dye degradation obeys first order kinetics and is explained on the basis of Langmuir-Hinshelwood mechanism. <br/> <br/>Page(s): 901-905 http://nopr.niscair.res.in/handle/123456789/9923 Title: Fluorescence resonance energy transfer from proflavin hemisulphate to rose bengal in aqueous micellar solution <br/> <br/>Authors: Bhattar, S L; Kolekar, G B; Patil, S R <br/> <br/>Abstract: The fluorescence resonance energy transfer from proflavine hemisulphate to rose bengal in aqueous sodium dodecyl sulfate has been investigated at room temperature using steady-state fluorescence spectroscopy technique. The fluorescence of proflavine hemisulphate is quenched by rose bengal and the quenching is in accordance with Stern-Volmer relationship. The efficiency of energy transfer is found to depend upon concentration of rose bengal. The value of critical energy transfer distance calculated by using Foster relationship (27.2 Å) is less than 50 Å, indicating efficient energy transfer occurs in this donor-acceptor pair. <br/> <br/>Page(s): 896-900 http://nopr.niscair.res.in/handle/123456789/9922 Title: Synthesis and characterization of a mixed cationic tetrasulfidotungstate monohydrate <br/> <br/>Authors: Srinivasan, Bikshandarkoil R; Mhalsikar, Rathan G; Näther, Christian; Bensch, Wolfgang <br/> <br/>Abstract: Synthesis and structural characterization of a mixed cationic tetrasulfidotungstate monohydrate (dabcoH)₃(NMe₄)[WS₄]₂. H₂O (dabco = 1,4-diazabicyclo[2.2.2]octane; NMe₄ = tetramethylammo-nium) is described. The compound crystallizes in the centrosymmetric monoclinic space group <i style="">P2₁/c</i> and its structure consists of three crystallographically independent monoprotonated (dabcoH)⁺ cations, a tetramethylammonium cation, two unique tetrasulfidotungstate anions, and a lattice water. The organic cations, [WS₄]^2- anion and lattice water are linked by several weak H-bonding interactions. <br/> <br/>Page(s): 891-895 http://nopr.niscair.res.in/handle/123456789/9921 Title: Speciation of chromium in aqueous samples by solid phase extraction using multiwall carbon nanotubes impregnated with D2EHPA <br/> <br/>Authors: Vellaichamy, S; Palanivelu, K <br/> <br/>Abstract: A solid phase extraction system has been developed for the speciation of chromium(III) and chromium(VI). This method is based on the adsorption of chromium(III) on D2EHPA impregnated with multiwall carbon nanotubes and has been compared with commercially available activated carbon impregnated with D2EHPA. The chromium concentration has been determined by inductively coupled plasma atomic emission spectroscopy. The effect of parameters such as <i>p</i>H of the aqueous solution, amount of adsorbent, contact time, initial ion concentration, sample volume, eluent type and D2EHPA concentration have been investigated. The results indicate that the maximum adsorption of chromium(III) is at <i>p</i>H 4.5 ± 0.1 on the multiwall carbon nanotubes. Desorption studies have been carried out with 0.25 <i style="">M</i> Br₂ in 1.0 <i style="">M</i> NaOH wherein quantitative recovery of the chromium(III) has been observed. The adsorption capacity of MWCNTs- D2EHPA is found to be 0.96 mg g ^-1 for chromium with detection limit of chromium 0.05 mg mL^-1.  The highest pre-concentration factor of 60 could be obtained for 300 mL of sample volume.  The developed method has been applied for the speciation of chromium in natural water sample and the pre-concentration method is satisfactory (recoveries > 98 %, rsd < 10 %, <i>n </i>= 5) for chromium species determination. <br/> <br/>Page(s): 882-890