Dav Post Graduate College

Dehradun, India

Dav Post Graduate College

Dehradun, India
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Kaushik R.D.,Gurukul Kangri University | Kumari R.,Gurukul Kangri University | Kumari R.,Dav Post Graduate College | Kumar T.,Gurukul Kangri University | And 3 more authors.
Asian Journal of Chemistry | Year: 2010

The reaction was found to be second order being first order in each reactant i.e., N,N-dimethylaniline (DMA) or N,N-diethylaniline (DEA) and the oxidant, periodate. The kinetics of the reaction has been followed by monitoring the increase in the absorbance of reaction intermediate, C. The rate law in accordance with the results under pseudo first order conditions, [IO- 4] >> [DMA or DEA], is given by: d[C]/dt = kKKw [S] [IO- 4]0[H+]/{K2Kw + (Kw + KbK2) [H+] + Kb[H+]2}, where kK = empirical composite rate constant, Kw is ionic product of water, K2 is acid dissociation constant of H4IO- 6, Kb is base dissociation constant of aniline taken and [IO- 4]0 represents the concentration of periodate that has been taken in excess. In agreement with the rate law the 1/k2 versus [H+] profile passes through the minimum (where k2 is second order rate constant). The rate of reaction remains unaffected by free radical scavengers and increases with increase in dielectric constant of the medium. Thermodynamic parameters evaluated are: Ea = 13.2 kcal mol-1, A = 5.89 × 109 dm3 mol-1 s-1; ΔS# = -16.2 cal mol-1 K-1, ΔG# = 17.6 kcal mol-1 and ΔH# = 12.6 kcal mol-1 for DEA oxidation and Ea = 16.1 kcal mol-1, A = 1.06 × 1012 dm3 mol-1 s-1; ΔS# = -6.32 cal mol-1 K-1, ΔG# = 17.4 kcal mol-1 and ΔH# = 15.5 kcal mol-1 for DMA oxidation. Main reaction products of the periodate oxidation of DEA are O-ethylquinoneoxime and p-nitrosophenetole while these are O-methylquinoneoxime and p-nitrosoanisole for DMA oxidation.

Misra A.K.,Banaras Hindu University | Mishra S.N.,Brahmanand College | Pathak A.L.,Brahmanand College | Misra P.,DAV Post Graduate College | Naresh R.,Uttar Pradesh Technical University
Applied Mathematics and Computation | Year: 2012

A delay mathematical model for the control of cholera epidemic is proposed and analyzed. It is assumed that the disease spreads through carriers, which makes the human food contaminated by transporting bacteria from the environment. It is also assumed that insecticides are used to control the carriers with the rate proportional to the density of carriers. The analysis of model shows that the disease may be controlled by spraying insecticides but a longer delay in spraying insecticides may destabilize the system. Simulation is also carried out to support the analytical results. © 2012 Elsevier Inc. All rights reserved.

Yadav S.,Dav Post Graduate College | Tyagiand D.K.,Dav Post Graduate College | Yadav O.P.,CCS Haryana Agricultural University
Nature Environment and Pollution Technology | Year: 2011

Equilibrium and kinetic data for the adsorption of Congo-red dye from aqueous solution onto activated rice husk carbon have been reported. T he effects of dye initial concentration, adsorbent-adsorbate contact time, temperature, adsorbent's amount and particle size on the percent adsorption of the dye on the adsorbent have been investigated. Kinetics of adsorption of Congo-red onto the adsorbent in aqueous solution was monitored s pec tr ophot ometr ically. At the specified dye initial concentration, percent adsorption of dye increases with increase in temperature as well as the adsorbate-adsorbent contact period. However, at the given temperature, % adsorption of Congo-red decreases with the increase in dye initial concentration. The observed adsorption data were analysed in light of Langmuir and Freundlich adsorption isotherms. Dye adsorption rate constant (k ad) follows the first order kinetics. Activation energy (E a) of adsorption, intra-particle diffusion rate constant and thermodynamic parameters of Congo-red adsorption on the rice-husk carbon have been evaluated and interpreted.

Kumar S.,Himachal Pradesh University | Chauhan G.S.,Himachal Pradesh University | Gupta R.,Himachal Pradesh University | Kant S.,Himachal Pradesh University | Sharma R.K.,DAV Post Graduate College
Desalination and Water Treatment | Year: 2014

Abstract: In the present study, muslin was modified by graft copolymerization with poly(4-vinyl pyridine) using γ-ray initiation method. The graft copolymers, thus synthesized, were further functionalized by reaction with 2-chloroethanol. The resultant materials, having pyridinium ring and exchangeable Cl−, were evaluated for the removal of fluoride ions from the simulated water samples. The materials exhibited high fluoride uptake and the maximum uptake was observed at pH 4.0, 20°C and 10 ppm of the fluoride ions. The maximum retention capacity of 7.7 mg/g was observed when fluoride uptake was studied up to 10 cycles. The data generated fit the pseudo-second-order kinetics and Langmuir isotherm. The efficacy of the functionalized muslin was evaluated as an antimicrobial agent against a bacterium (Bacillus aureus) and a fungus (Aspergillus niger). It was observed to be effective to inhibit the growth of both the microbes. © 2013, © 2013 Balaban Desalination Publications. All rights reserved.

Saxena K.,Defence Materials and Stores Research and Development Establishment | Bisaria C.S.,Defence Materials and Stores Research and Development Establishment | Kalra S.J.S.,Dav Post Graduate College | Saxena A.K.,Defence Materials and Stores Research and Development Establishment
Progress in Organic Coatings | Year: 2015

Synthesis and properties of poly(imide-siloxane) hybrid polymers (PIS), having alternate diimide and disiloxane units, based on 1,3-bis(succinyl anhydride)1,1,3,3-tetraorganodisiloxane (I or II) have been described. Polymers have been synthesized by the precursor synthesis i.e., poly(amic acid), using siloxanes (I or II) and 4,4′-diaminodiphenylmethane (DDM) or 4,4′-diaminodiphenylsulphone (DDS) in N,N-dimethylacetamide (DMAc) followed by thermal imidization. FT-IR, thermal (TGA and TMA), solvent resistant and dielectric properties of the compounds have also been studied. The glass transition, thermal stability and char yields of these hybrid polymers increased appreciably. These materials also showed very good solvent resistant properties in protic and aprotic solvents. © 2014 Elsevier B.V. All rights reserved.

Kumar V.,Dav Post Graduate College | Kumar M.,Dav Post Graduate College | Tripathi M.R.,Dav Post Graduate College
Asian Journal of Chemistry | Year: 2010

The dipole moments of Pt(NO2-acac)2 and its molecular complexes formation with heterocyclic N-bases have been studied by refractive index, Guggenheim and dielectric plot methods. The formation of charge transfer complexes Pt(NO2-acac)2 with heterocylic N-bases is further supported by dipole moment studies. It is found that acetylacetone has larger dipole moment than its metal chelates, which may be interpreted due to its non-planar structure. The symmetry of Pt(acac)2 is disturbed when γ-H of this chelate is replaced by the nitro group. An increase in the dipole-moment was observed in these systems after complexation. The maximum dipole moment of Pt(NO2-acac)2 pyridine complex was observed which indicates stronger interaction with pyridine in comparison to other donors. The dipole moment of these complexes has been found in consistent with those of K1 values obtained from conductometric methods. It is also observed that the value of dipole moment increases with increase in the temperature for Pt(NO2-acac)2-pyridine or quinoline complex. The values are greater for pyridine system at different temperatures. The dielectric titration technique has indicated 1:1 stoichiometry of these charge-transfer complexes. From this study it has been observed that more polar is the solute the larger is the expected increase in its dipole moment values. It is suggested that the interaction of Pt(NO2-acac)2 with N-bases is governed by dipole electrostatic attraction.

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