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991.
Titanium containing silica analog of ZSM-48 (TS-48) has been synthesized by a new method using hexamethonium hydroxide as a template. Titanium incorporation in the framework was evidenced from unit cell volume expansion, framework IR spectra and diffuse reflectance UV-Vis spectra. 相似文献
992.
Hydroxyapatite photocatalytic degradation of calmagite (an azo dye) in aqueous suspension 总被引:1,自引:0,他引:1
M. Pratap Reddy A. Venugopal M. Subrahmanyam 《Applied catalysis. B, Environmental》2007,69(3-4):164-170
The hydroxyapatite (HAP) is prepared by precipitation method and examined for the photocatalytic degradation of calmagite, a toxic and non-biodegradable azo-dye compound. The physicochemical properties of hydroxyapatite material were characterized using BET surface area, XRD, FT-IR, and SEM analysis. The FT-IR analysis of the hydroxyapatite revealed that the peak intensity due to absorbance of surface PO43− group centered at wave number 1030 cm−1 is drastically decreased upon exposure to UV for 1 h. The study includes dark adsorption experiments at different pH conditions, influence of the amount of catalyst, and effect of pH on photocatalytic degradation of dye, chemical oxygen demand (COD) removal, biological oxygen demand (BOD5) increase and SO42− and NO3− ions evolution during the degradation. At optimum photocatalytic experimental conditions the same is compared with commercial degussa P-25 TiO2. The photocatalytic treatment significantly reduced the COD (92% removal) and increased the BOD5/COD ratio to 0.78. Considerable evolution of SO42− (8.5 mg L−1) and NO3− (12.2 mg L−1) ions are achieved during the degradation process, thus reflecting the usefulness of the hydroxyapatite photocatalytic treatment in calmagite removal in wastewater. 相似文献
993.
Rama Subba Reddy Gorla 《Chemical Engineering Communications》1994,130(1):167-179
The steady state flow and heat transfer characteristics of a laminar cylindrical wall jet are obtained for uniform surface heat flux conditions. Local nonsimilarity solutions as well as series solutions are presented for the velocity and thermal fields. Numerical results are given for the wall shear stress, surface temperature variation and temperature field for a Prandtl number of 0.73. 相似文献
994.
John B. McLaughlin Venkat Reddy Richard J. Nunge 《Chemical Engineering Communications》1986,41(1):181-214
The viscous wall region of a fully developed turbulent pipe flow is investigated using a nonlinear, time-dependent, three-dimensional model. In the model, the velocity field is assumed to satisfy periodic boundary conditions in the longitudinal and spanwise directions, the velocity vanishes at the pipe wall, the velocity fluctuations are assumed to vanish at large distances from the wall, and a law of the wall profile is imposed on the longitudinal and spanwise average of the longitudinal component of velocity outside the viscous wall region. The model equations are solved using pseudospectral methods and the computed mean velocity profile, fluctuation intensities, and turbulence production rate are found to be in good agreement with experiment in the viscous wall region. It is found that the bulk of turbulence production is generated by length scales larger than 40 in the spanwise direction and 200 in the longitudinal direction. 相似文献
995.
2-Phenylethyl acrylate (PEA) and 2-Phenylethyl methacrylate (PEMA) were synthesized by reacting 2-Phenyl ethanol with acryloyl and methacryloyl chloride respectively. Homopolymers and copolymers were prepared by free radical polymerization technique using benzoylperoxide as initiator. Copolymers of PEA and PEMA with methyl acrylate (MA) and N-vinyl pyrollidone (NVP) of different compositions were prepared. The monomers and polymers were characterized by IR and NMR techniques. Thermal stability of the polymers were determined by TG analysis. The composition of the copolymer was determined using 1H-NMR analysis. The reactivity ratios of the monomers were determined by the application of Finemann–Ross and Kelen–Tudos methods. The prepared copolymers were tested on leather for their pressure sensitive adhesive property. 相似文献
996.
[2,6‐Bis(4‐hydroxybenzylidene)cyclohexanone] (HBC) was prepared by reacting cyclohexanone and p‐hydroxybenzaldehyde in the presence of acid catalyst. Acrylated derivative of HBC, 4‐{[‐3‐(4‐hydroxybenzylidene)‐2‐oxocyclohexylidene]methyl}phenyl acrylate (HBA), was prepared by reacting HBC with acryloyl chloride in the presence of triethylamine. Copolymers of HBA with styrene (S) and methyl acrylate (MA) of different feed compositions were carried out by solution polymerization technique by using benzoyl peroxide (BPO) under nitrogen atmosphere. All monomers and polymers were characterized by using IR and NMR techniques. Reactivity ratios of the monomers present in the polymer chain were evolved by using Finnman–Ross (FR), Kelen–Tudos (KT), and extended Kelen–Tudos (ex‐KT) methods. Average values of reactivity were achieved by the following three methods: r1 (S) = 2.36 ± 0.45 and r2 (HBA) = 0.8 ± 0.31 for poly(S‐co‐HBA); r1 = 1.62 ± 0.06 (MA); and r2 = 0.12 ± 0.07 (HBA) for poly(MA‐co‐HBA). The photocrosslinking property of the polymers was done by using UV absorption spectroscopic technique. The rate of photocrosslinking was enhanced compared to that of the homopolymers, when the HBA was copolymerized with S and MA. Thermal stability and molecular weights (Mw and Mn) were determined for the polymer samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2494–2503, 2004 相似文献
997.
The isocyanate-terminated urethane prepolymer was prepared from toluene diisocyanate and a mixture of castor oil-polypropylene glycol (PPG) (MW 2000). The chlorinated rubber (CR) graft copolymers (A and B) containing small percentage of hydroxyl groups were mixed with the urethane prepolymer in different proportions (1:1, 2:3, and 1:2), and the films were cast using these systems. Tensile strength and percent elongation were evaluated for A and B series with and without triethanolamine (TEA). Morphological characteristics of the films were also studied by using a scanning electron microscope (SEM). Deviations noticed in tensile strength values at yield as well as at break for A and B series and for the samples cured with additional TEA have been discussed. 相似文献
998.
The rates of the individual reactions of 2-methylol-4-t-butylphenol with 4-t-butylphenol were measured under varying mole ratios of reactants in the presence of different acid catalysts (5.0 × 10?3 N to 2.0 × 10?4 N) at five different temperatures (60, 65, 70, 75, and 80°C). In all the experiments, the reactions were found to obey second-order rate law. The values of the Arrhenius parameters and the entropy of activation for the overall reaction were calculated. The relative catalytic efficiencies of the acid catalysts followed the order HNO3 > HCl > H2SO4. 相似文献
999.
Titanium silicalite molecular sieves, TS-1 and TS-2 having MFI and MEL structures, respectively, catalyze the oxidation of secondary amines to the corresponding hydroxylamines using hydrogen peroxide as the oxidant. Higher concentrations of H2O2 lead to further oxidation of hydroxylamine to nitrone. Diffuse reflectance spectroscopy shows the formation of a titanium peroxo complex upon addition of hydrogen peroxide to the TS-1 catalyst. The titanium peroxo complex oxidizes the substrate and reforms to a titanyl group. 相似文献
1000.
Rama Subba Reddy Gorla 《Chemical Engineering Communications》1986,49(1):13-22
An analysis is presented to study the effects of buoyancy-induced streamwise pressure gradients on laminar forced convection heat transfer to non-Newtonian fluids from a horizontal plate. Numerical solution of the transformed boundary layer equations has been carried out for different values of the flow behavior index and the buoyancy parameter by means of the local nonsimilarity method. A discussion is provided for the effect of the buoyancy force on the friction factor, the dimensionless heat transfer rate and the details of the velocity as well as temperature fields. 相似文献