http://nopr.niscair.res.in/handle/123456789/9004 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/16790 Title: Role of triethanolamine and furfuraldehyde on the electrochemical deposition and dissolution- behaviour of zinc <br/> <br/>Authors: Rethinam, A John; Bapu, G N K Ramesh; Muralidharan, V S <br/> <br/>Abstract: The search for the development of non-cyanide zinc plating baths resulted in identification of newer complexing ligands. The deposition and dissolution of zinc was studied by cyclic voltammetric studies using a bath composition consisted of 0.12M Zinc oxide, 2.75M sodium hydroxide and required quantity of triethanolamine and furfuraldehyde. Glassy carbon (GC), Platinum and SCE were used as working electrode, counter electrode and reference electrode respectively. The studies were made at different concentrations of the above additives at various scan rates at 30°C, The pH of the bath was maintained at 11.5 to 12.0. The deposition of zinc from zincate solutions undergoes successive reduction to zinc. The chemical step followed by first electron transfer is the slow step. Triethanolamine and furfuraldehyde were found to participate in the electron transfer process. Detailed mechanism of deposition and dissolution in presence of triethanolamine and furfuraldehyde are discussed. <br/> <br/>Page(s): 207-212 Fri, 27 Feb 2004 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/16786 Title: Study on the fluoride removal characteristics of mineral (fluorapatite) <br/> <br/>Authors: Singh, I B; Prasad, M <br/> <br/>Abstract: The effectiveness of low grade fluorapatite bearing mineral on fluoride removal has not been examined earlier. For identification of such mineral, a preliminary assessment of performance of mineral is essential in order to know which aspect is necessary to carry out further research for development of mineral based defluoridation technology. In this study batch adsorption study was performed to evaluate the fluoride removal potential of low cost rock phosphate (fluroapatite) mineral at pH 4, 5 and 6. The optimum dose was determined to be 1.5, 2.5 and 3.5 g mineral at pH 4, 5 and 6, respectively. The first order adsorption rate constants derived by Lagergren equation at different pH, clearly indicates the fast removal kinetics at pH 4. The comparatively high solubility of mineral and an increase of calcium concentration at pH 4 appears to be the main reason for fast removal reaction. There was no effect of mineral quantity on fluoride removal after solution pH became alkaline. The various aspects of the study including recyclability of mineral are discussed. <br/> <br/>Page(s): 185-189 Fri, 27 Feb 2004 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/16785 Title: Role of matrix material in the characterization of high-purity copper by flame and graphite furnace AAS <br/> <br/>Authors: Kumar, Sanjukta A; Sanglikar, Manisha B; Shaikh, Mahzebin S; Sudersanan, M <br/> <br/>Abstract: Matrix effect in the determination of trace metallics in high-purity copper has been evaluated for estimation of Ag, Cr, Fe, Ni, Pb, Sb, and Zn by FAAS and GFAAS. Matrix effects were less significant for FAAS while it was quite important for GFAAS. Methods have been standardized for determination of various trace elements after separation of matrix element and pre-concentration of the analytes. For separation of matrix two different procedures were standardized: (i) co-precipitation of metal hydroxides using La as carrier and (ii) electro deposition. To validate the method, the recovery of metal ions were tested and were found to be satisfactory. The methods have been applied to the determination of these impurities in high-purity copper samples. For the determination of silver, a selective deposition method was adopted in order to avoid co-deposition of copper. These three different modes of matrix separation were found to be complementary to each other for determination of various critical trace elements in high purity electrolytic copper. <br/> <br/>Page(s): 170-177 Fri, 27 Feb 2004 22:58:59 GMT http://nopr.niscair.res.in/handle/123456789/16784 Title: Synthesis and characterization of SAPO-35 from non-aqueous systems with different silicon content <br/> <br/>Authors: Venkatathri, N; Sivasanker, S <br/> <br/>Abstract: The molecular sieve SAPO-35 with different silicon content has been synthesized in a non-aqueous medium using haxamethyleimine template. It has been characterized by XRD, SEM, Carbon and Nitrogen analysis, MASNMR, FT-IR techniques and Methanol to olefin reaction. The study indicates that XRD, FT-IR and ²⁹Si MASNMR properties did not change on increase in silicon incorporation. No silicon ilands were found on increase in silicon concentration. However, SEM photograph reveals that the particle size increased on increase in silicon content in the framework. The morphology also changes from bundles of platlets to cuboid, on more silicon incorporation. The catalytic activity of methanol to olefin conversion increases with silicon content and the selectivity is higher than ZSM-5 catalyst. Butene is formed as a main product. <br/> <br/>Page(s): 260-265 Fri, 27 Feb 2004 22:58:59 GMT