Showing papers by "Thapar University published in 2012"

Polymer-supported metals and metal oxide nanoparticles: synthesis, characterization, and applications

Abstract: Metal and metal oxide nanoparticles exhibit unique properties in regard to sorption behaviors, magnetic activity, chemical reduction, ligand sequestration among others. To this end, attempts are being continuously made to take advantage of them in multitude of applications including separation, catalysis, environmental remediation, sensing, biomedical applications and others. However, metal and metal oxide nanoparticles lack chemical stability and mechanical strength. They exhibit extremely high pressure drop or head loss in fixed-bed column operation and are not suitable for any flow-through systems. Also, nanoparticles tend to aggregate; this phenomenon reduces their high surface area to volume ratio and subsequently reduces effectiveness. By appropriately dispersing metal and metal oxide nanoparticles into synthetic and naturally occurring polymers, many of the shortcomings can be overcome without compromising the parent properties of the nanoparticles. Furthermore, the appropriate choice of the polymer host with specific functional groups may even lead to the enhancement of the properties of nanoparticles. The synthesis of hybrid materials involves two broad pathways: dispersing the nanoparticles (i) within pre-formed or commercially available polymers; and (ii) during the polymerization process. This review presents a broad coverage of nanoparticles and polymeric/biopolymeric host materials and the resulting properties of the hybrid composites. In addition, the review discusses the role of the Donnan membrane effect exerted by the host functionalized polymer in harnessing the desirable properties of metal and metal oxide nanoparticles for intended applications.

Utilization of wood ash in concrete manufacturing

Abstract: Solid waste management is the prime concern globally due to ever increasing quantities of waste materials and industrial by-products. Scarcity of land-filling space and because of its ever increasing cost, recycling and utilization of industrial by-products and waste materials has the only option. There are several types of such materials. The utilization of such materials in concrete not only makes it economical, but also helps in reducing disposal concerns. One such material is wood ash (WA). Wood ash (WA) is the residue generated due to combustion of wood and wood products (chips, saw dust, bark, etc.). It is the inorganic and organic residue remaining after the combustion of wood or unbleached wood fiber. This paper details about the physical, chemical, elemental and mineralogical composition of wood ash. It highlights the influence of wood ash on the slump, water absorption, compressive strength, splitting tensile strength, flexural strength, freezing and thawing resistance, and shrinkage of concrete. It also deals with the leaching behavior of wood ash.

A new approach for solving fuzzy transportation problems using generalized trapezoidal fuzzy numbers

Abstract: In the literature, several algorithms are proposed for solving the transportation problems in fuzzy environment but in all the proposed algorithms the parameters are represented by normal fuzzy numbers. Chen [Operations on fuzzy numbers with function principal, Tamkang Journal of Management Science 6 (1985) 13-25] pointed out that in many cases it is not to possible to restrict the membership function to the normal form and proposed the concept of generalized fuzzy numbers. There are several papers in the literature in which generalized fuzzy numbers are used for solving real life problems but to the best of our knowledge, till now no one has used generalized fuzzy numbers for solving the transportation problems. In this paper, a new algorithm is proposed for solving a special type of fuzzy transportation problems by assuming that a decision maker is uncertain about the precise values of transportation cost only but there is no uncertainty about the supply and demand of the product. In the proposed algorithm transportation costs are represented by generalized trapezoidal fuzzy numbers. To illustrate the proposed algorithm a numerical example is solved and the obtained results are compared with the results of existing approaches. Since the proposed approach is a direct extension of classical approach so the proposed approach is very easy to understand and to apply on real life transportation problems for the decision makers.

Use of iron and steel industry by-product (GGBS) in cement paste and mortar

Abstract: With the increased industrialization, generation of industrial by-products has increased significantly. There are many types of industrial by-products depending upon the industry. Utilization of such types of by-products has become an enormous challenge. One such type of by-product is ground granulated blast furnace slag (GGBS) which is produced from the blast-furnaces of iron and steel industries. GGBS is very useful in the design and development of high quality cement paste/mortar and concrete. This paper presents comprehensive details of the physical, and chemical properties, and hydration reaction. It also covers the workability, setting times, compressive strength, chloride and sulfate resistance of cement paste and mortar.

Structural, magnetic, and electrical properties of Gd-doped BiFeO 3 nanoparticles with reduced particle size

Abstract: Pure and Gd-doped BiFeO3 nanoparticles have been synthesized by sol–gel method. The significant effects of size and Gd-doping on structural, electrical, and magnetic properties have been investigated. X-ray diffraction study reveals that the pure BiFeO3 nanoparticles possess rhombohedral structure, but with 10% Gd-doping complete structural transformation from rhombohedral to orthorhombic has been observed. The particle size of pure and Gd-doped BiFeO3 nanoparticles, calculated using Transmission electron microscopy, has been found to be in the range 25–15 nm. Pure and Gd-doped BiFeO3 nanoparticles show ferromagnetic character, and the magnetization increases with decrease in particle size and increase in doping concentration. Scanning electron microscopy study reveals that grain size decreases with increase in Gd concentration. Well-saturated polarization versus electric field loop is observed for the doped samples. Leakage current density decreases by four orders by doping Gd in BiFeO3. The incorporation of Gd in BiFeO3 enhances spin as well as electric polarization at room temperature. The possible origin of enhancement in these properties has been explained on the basis of dopant and its concentration, phase purity, small particle, and grain size.

Use of cement kiln dust in cement concrete and its leachate characteristics

Abstract: Due to continuous increase in industrial globalization and generation of waste, solid waste management has become one of the major global environmental issue. Cement kiln dust (CKD) is one of such industrial waste or by product which is progressively significant environmental concern related to its emission and disposal. CKD is fine grained, solid, highly alkaline particulate material chiefly composed of oxidized, anhydrous, micron-sized particles collected from electrostatic precipitators during the production of cement clinker. Cement kiln dust so generated is partly reused in cement plants and landfilled. Due to lack of landfilling space and ever increasing disposal cost, utilization of CKD in highway uses, waste treatment, soil stabilization, cement mortar/concrete, CLSM, etc. has become an attractive alternative to its disposal. The leachate obtained from cement kiln dust may contain hazardous compounds and its caustic nature poses harmful effects to the environment. So, it is essential to know the characteristics of leachate obtained from CKD for beneficial utilization towards solid waste management. Several studies have shown that CKD could be used in making cement paste/mortar/concrete. This paper presents the overview of some of the research published on the beneficial use of CKD in construction materials, reducing carbon dioxide emissions and CKD leachate characteristics. Effect of CKD on the cement paste/mortar/concrete properties like compressive strength, tensile strength, durability, hydration, electrical conductivity, etc. and leachate test methods and leachate characteristics of cement kiln dust is also discussed in this paper.

Nanocrystalline K–CaO for the transesterification of a variety of feedstocks: Structure, kinetics and catalytic properties

Abstract: The work presented in current manuscript demonstrated the preparation of potassium ion impregnated calcium oxide in nano particle form and its application as solid catalyst for the transesterification of a variety of triglycerides. The catalyst was characterized by powder X-ray diffraction, scanning electron and transmission electron microscopic, BET surface area measurement, and Hammett indicator studies in order to establish the effect of K+ impregnation on catalyst structure, particle size, surface morphology, and basic strength. The catalyst prepared by impregnating a mass fraction of 3.5% K+ in CaO was found to exist as similar to 40 nm sized particles, and same was employed in present study as solid catalyst for the transesterification of a variety of feedstocks viz., mutton fat, soybean, virgin cotton seed, waste cotton seed, castor, karanja and jatropha oil. Under optimized conditions, K-CaO was found to yield 98 +/- 2% fatty acid methyl esters (FAMEs) from the employed feedstocks, and showed a high tolerance to the free fatty acid and moisture contents. A pseudo first order kinetic model was applied to evaluate the kinetic parameters and under optimized conditions first order rate constant and activation energy was found to be 0.062 mm(-1) and 54 kJ mol(-1), respectively. The Koros-Nowak criterion test has been employed to demonstrate that measured catalytic activity was independent of the influence of transport phenomenon. Finally, few physicochemical properties of the FAMEs prepared from waste cotton seed oil, karanj a oil and jatropha oils have been studied and compared with European standards. (C) 2012 Elsevier Ltd. All rights reserved.

Optimal parameter settings for rough and finish machining of die steels in powder-mixed EDM

Abstract: The present study was undertaken to identify the appropriate parameter settings for rough and finish machined surface for EN31, H11, and high carbon high chromium (HCHCr) die steel materials in a powder-mixed electric discharge machining process. The effect of seven different process variables along with some of their interactions was evaluated using a dummy-treated experimental design and analysis of variance. Material removal rate (MRR), tool wear rate, and surface finish were measured after each trial and analyzed. The parameter settings for rough and finished machining operations were obtained. EN31 exhibited maximum MRR as compared to the other two materials at similar process settings. Copper (Cu) electrode with aluminum suspended in the dielectric maximized the MRR. Suspending powder in the dielectric resulted in surface modification. Graphite powder showed a lower MRR but improved the surface finish. HCHCr require higher current and pulse on settings for initiating a machining cut and works best in combination with tungsten–Cu electrode and graphite powder for improved finish. The MRR for H11 is lower than EN31 but significantly higher than HCHCr under same process conditions.

Size and shape dependent attachments of Au nanostructures to TiO2 for optimum reactivity of Au–TiO2 photocatalysis

Abstract: This study demonstrated the effects of supported Au nanoparticles of various sizes and shapes on its co-catalytic activity imparted to TiO 2 during photocatalytic oxidation of salicylic acid. The TiO 2 photoactivity is remarkably improved with the decreasing size (9.5 ± 0.06 to 3.5 ± 0.25 nm) and increasing surface to volume (S/V) ratio (0.629–1.95 nm −1 ) of spherical Au co-catalysts loading. The amount of Au (0.02 wt%) nanostructures supported to TiO 2 for its optimum photoreactivity is found to be 100 times less than the conventional prerequisite of 1–2 wt% metal photodeposition. The Au nanorod (aspect ratio = 2.8 ± 0.12 and S/V = 0.54 nm −1 ) attachment to TiO 2 significantly decreased the photoactivity compared with the highly active quantum size (3.5 ± 0.25 nm) Au co-catalysts loading. The interaction of Au nanoparticles of various morphology with TiO 2 induces the photoexcited charge transfer process in varied extent, leading to diverse photocatalytic activity. Zeta potential (surface charge and conductance) measurement of aqueous dispersion of TiO 2 , Au nanoparticles and salicylic acid was carried out to investigate the interaction among the various components in the photoreaction system.

Effect of modifiers field strength on optical, structural and mechanical properties of lanthanum borosilicate glasses

Abstract: An attempt has been made to understand the role of modifiers on physical, mechanical and spectroscopic properties of AO-SiO 2 –B 2 O 3 -La 2 O 3, (A = Mg, Ca, Sr, Ba) glasses. The replacement of alkaline earth metals which act as modifier in glass matrix exhibit, marked difference in their strength and optical properties. The results are discussed in light of non-bridging oxygens (NBO), optical basicity, refractive index, polarisability, hardness and fracture toughness. In addition to this, Weibull statistics and cumulative probability of failure have also been analyzed. Band gap of glasses has been calculated using UV–visible spectroscopy where the variation in band gap is observed to increase with the addition of heavier modifier. Raman features have been explored for all prepared samples through Raman spectra which is in agreement with Fourier transform infra-red (FTIR) spectroscopy and Fourier transform nuclear magnetic resonance (FT-NMR).

Coupled Higgs field equation and Hamiltonian amplitude equation: Lie classical approach and (G′/G)-expansion method

Abstract: In this paper, coupled Higgs field equation and Hamiltonian amplitude equation are studied using the Lie classical method. Symmetry reductions and exact solutions are reported for Higgs equation and Hamiltonian amplitude equation. We also establish the travelling wave solutions involving parameters of the coupled Higgs equation and Hamiltonian amplitude equation using (G′/G)-expansion method, where G = G(ξ) satisfies a second-order linear ordinary differential equation (ODE). The travelling wave solutions expressed by hyperbolic, trigonometric and the rational functions are obtained.

Solitons and other nonlinear waves of the Boussinesq equation

Abstract: This paper studies the dynamics of shallow water waves that are governed by the Boussinesq equations A few perturbation terms are taken into account The ansatz method is used to carry out the perturbed Boussinesq equation Later on, the mapping method is used to extract a few more analytical solutions Additionally, the Weierstrass elliptic function method is also used to obtain solitary waves and singular soliton solutions Finally, the Lie symmetry approach is used to extract a few more additional solutions

FTIR structural investigation of gamma irradiated BaO–Na2O–B2O3–SiO2 glasses

Abstract: Fourier transform infrared (FT-IR) spectra of xBaO–15Na2O–(70−x)B2O3–15SiO2 glass system with x=0, 5, 10, 15 and 20 (mol%) has been measured in the spectral range 400–4000 cm−1 at room temperature in order to understand the characteristic frequencies of the chemical bonds and bonding mechanisms, which are susceptible to the structural and spectral changes. The effect of gamma irradiation in the dose range 0.1 kGy–60 kGy on the infrared absorption spectra of these glasses is also reported. The change in the glass structure due to the effect of composition is also discussed. It has been observed that irradiation of the glasses with the gamma rays increases the BO3 groups and the non bridging oxygens which make the network loose.