http://nopr.niscair.res.in/handle/123456789/6823 Search the Channel search http://nopr.niscair.res.in/simple-search http://nopr.niscair.res.in/handle/123456789/7110 Title: Acridine orange and chlorite reaction — An indicator reaction for the trace determination of Ru(III) <br/> <br/>Authors: Bhagwat, V W; Vijay, Rajani; Jonnalgadda, S B; Pare, Brijesh <br/> <br/>Abstract: Catalysis by transition metal ions plays an important role in understanding the mechanistic aspects of a particular redox reaction. Ru(III) acts as an efficient and potential catalyst in many redox reactions. Hence the use of Ru(III) chloride as a homogeneous catalyst in acidic medium is of present interest. Based on the highly selective catalytic efficiency of Ru(III) on the oxidation of acridine orange {3,6-bis (dimethylamino) acridine zinc chloride double salt}(AO⁺) by acidic chlorite, a fixed-time kinetic analytical procedure for determination of Ru(III) is developed. The lowest determination limit attainable with the developed method is 1.01 ng/mL. The method allows determination of Ru(III) with no interference from a wide range of cations. Tolerance ratios have also been computed. With excess concentration of reactants, both un-catalyzed and catalyzed reactions follow a pseudo-first order kinetics in [AO⁺], fractional order kinetics in oxidant and first order kinetics in catalyst [Ru(III)]. The rate coefficient of the un-catalyzed reaction is 4.45<img src='/image/spc_char/cross.gif' border=0>10^-4s^-1 while the catalytic constant for the catalyzed reaction is 8.00<img src='/image/spc_char/cross.gif' border=0>10^-4s^-1. Retarding effect of increasing ionic strength suggests the involvement of oppositely charged species in rate determining step. A tentative mechanism has also been proposed based on the results of variation of various factors. <br/> <br/>Page(s): 644-647 http://nopr.niscair.res.in/handle/123456789/7109 Title: Vapour phase transesterification over modified ZrO₂-Al₂O₃ and ZrO₂-SiO₂for the synthesis of isoamyl salicylate <br/> <br/>Authors: D’Souza, Joyce; Nagaraju, N <br/> <br/>Abstract: Vapour phase transesterification of methyl salicylate with isoamyl alcohol in the presence of simple oxides, mixed oxides and their modified forms as catalysts was carried out. A systematic study was made with zirconia, alumina and silicaand the complete series of zirconia-alumina and zirconia-silica mixed oxides for 10-100% composition of zirconia, as well as the sulphate, phosphate and borate treated forms to identify the most suitable catalyst for this reaction.<b style=""> </b>All the catalysts used for the study exhibited catalytic activity for this transesterification reaction. The only side-product formed was phenol, apart from the primary byproduct methanol. The catalytic activity of zirconia, alumina and silica is in the range of 12 to 15%. There is a significant increase in the catalytic activity when these simple oxides are modified by sulphate, borate and phosphate ions. The trend in the increase in activity on modification is zirconia > alumina > silica. Among the anions, the trend in the increase in the activity is sulphate > phosphate > borate. However, the phosphated forms score over the sulphated forms for this reaction because (a) the activity of phosphated forms does not reduce with time on stream up to 2 h while there is a noticeable reduction in the catalytic activity of sulphated forms within 15 minutes from the start of the reaction and (b) there is no coke formation when the phosphated forms are used while sulphated forms lead to excessive coke formation and loss of reactants. The mixed oxide ZrO₂-Al₂O₃ of 20% ZrO₂ composition modified with phosphate ions is found to be the most suitable catalyst for this reaction. <br/> <br/>Page(s): 640-643 http://nopr.niscair.res.in/handle/123456789/7108 Title: Determination of thermo-physical properties of freeze-dried foodstuffs <br/> <br/>Authors: Chakraborty, R; Saha, A K; Bhattacharya, P <br/> <br/>Abstract: The thermo-physical properties of some important foodstuffs have been estimated and are correlated with temperature and pressure using semi-empirical technique. For determination of thermal conductivities (k) of paneer and mango samples, ‘Uniformly Retreating Ice Front’ (URIF) model has been used at two different methods of freezing conditions i.e. conventional slow freezing and rapid cryogenic freezing. In all the cases, linear equation expressing <i style="">k</i> as dependent variable with chamber pressure (<i style="">P</i>) [ranging from 0.003 to 0.05 mbar]<b style=""> </b>and average temperature of dried layer (<i style="">T</i>) [ranging from 275 to 295 K] as independent variables has been established. The heat capacity, <i style="">C</i>_p of different freeze-dried foodstuffs have been determined experimentally using ‘Differential Scanning Calorimeter’ for a wide range of temperature at specific values of moisture content of practical significance. The equations of the best fit curves are also presented, enabling one to estimate the heat capacity value for freeze dried foodstuff (with specified moisture content) at any temperature within the range of 258 to 319 K. <br/> <br/>Page(s): 597-604 http://nopr.niscair.res.in/handle/123456789/7107 Title: Studies on bacterial growth and lead(IV) biosorption using <i style="">Bacillus subtilis</i> <br/> <br/>Authors: Hossain, Sk Masud; Anantharaman, N <br/> <br/>Abstract: Gram-positive bacterium <i style="">Bacillus subtilis</i> biosorbs lead(IV) ion from its aqueous solution. The maximum biosorption of lead is 97.68% (<i style="">w</i>/<i style="">w</i>) within 48 h of incubation time with optimum <i style="">p</i>H 4.5 and optimum temperature 40°C for 700 ppm initial loading of lead in a shake flask (optimum rpm 60). 7 days old and 30% (<i style="">v</i>/<i style="">v</i>) of suspension inoculum culture is used in the studies. Lead is measured by using atomic absorption spectrophotometer (AAS) into an air-acetylene flame and absorbance is measured at 283.3 nm. The maximum bacterial growth is noticed as 4.90<img src='/image/spc_char/cross.gif' border=0>10⁸cells/mL at optimum bioprocess conditions. <br/> <br/>Page(s): 591-596