Spectroscopic and Chromatographic Identification of Hydrocarbon Group Types in Pakistani Crude Oils

Two crude oil samples collected from Paniro and Tangri (Sindh) southern Pakistan. The distillate fractions of both crude oil samples were analysed by U.V‐visible spectrophotometer and column chromatography for hydrocarbon group types. It was found from the physico‐chemical study of these crude oils that Tangri crude oil contains mostly paraffinic contents while Paniro crude oil samples are rich in aromatics. It was concluded from all the experiments that Tangri crude oil is paraffinic in nature; while Paniro crude oil is naphthenic in nature, further it was observed that Tangri crude oil processing would be environmentally friendly compared to Paniro crude oil, because Paniro crude contains a high amount of polyaromatics.     

Environmentally Friendly Recovery and Characterization of Oil from Used Engine Lubricants

The present paper demonstrates the review of some acid processes as well as development of some new solvent processes for reclamation of used lubricating oils. The conventional processes are found to be of low yield (? 50%), laborious, time consuming and environmentally hazardous, because of residual acidic sludge. Based on the findings, a new modified Aluminium sulphate‐sodium silicate‐acid‐base method employing a small quantity of acid and giving a high yield (? 60%) is proposed. Further, to avoid use of acid, new regeneration processes based on solvent extraction were investigated. They are termed CCl₄‐alcohol method, Dodecane‐alcohol method and Toluene‐alcohol method. These processes are not only cost effective in terms of complete solvent recovery, but are rapid, less time consuming, more environmentally friendly and gave a high yield (70–75%). The virgin lubricants (Castrol GTX and Rimula‐C) as well as oils recovered by different methods were also characterized physicochemically to determine kinematic viscosity, density, refractive index, carbon distribution, wear scar diameter, % Conradson carbon residue, % ash, % chloride, pour point, etc. Results obtained show that many of the physico‐chemical properties of the recovered oils are in good agreement with those of virgin oils. The n.d.M analysis was also performed which shows that virgin oils have 73 ± 3% paraffinic carbon, 26 ± 3% naphthenic carbon and about 1% aromatic carbon. The recovered oils also showed nearly the same chemical composition. The UV‐Visible spectra of the recovered oils are all similar to those of virgin lubricants. The results suggest that the oils recovered by solvent treatments, particularly Dodecan‐alcohol and Toluene‐alcohol methods, may serve for lubrication purposes and can be rendered as excellent as virgin lubricants with the addition of certain additives. The proposed methods may be considered as alternative cost effective green techniques for acid reclamation processes and being the motivation of the present investigation.     

TEMPO-catalyzed aerobic oxidation of alcohols to aldehydes and ketones in ionic liquid [bmim][PF6

[reaction: see text]. A simple and mild TEMPO-CuCl catalyzed aerobic oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones in ionic liquid [bmim][PF6] with no trace of overoxidation to carboxylic acids has been developed. The product can be isolated by a simple extraction with organic solvent, and the ionic liquid can be recycled or reused.     

Field emission investigations of RuO2-doped SnO2 wires

Field emission studies of a bunch and a single isolated RuO₂:SnO₂ wire have been performed. A current density of 5.73 × 10⁴ A/cm² is drawn from the single wire emitter at an applied field of 8.46 × 10⁴ V/μm. Nonlinearity in the Fowler-Nordheim (F-N) plot has been observed and explained on the basis of electron emission from both the conduction and the valence bands of the semiconductor. The current stability recorded at the preset value of 1.5 μA is observed to be good. Overall the high emission current density, good stability and mechanically robust nature of the RuO₂:SnO₂ wires offer advantages as field emitters for many potential applications.     

Determination of lanthanides in uranium solutions by X-ray fluorescence spectrometry

An XRF-method for the determination of Sm, Gd, Dy, Er and Eu in uranium solution by use of simple polyethylene bottles has been established. Spectral interferences and matrix effects like absorption enhancement have been rectified using standards of similar composition in the absence of internal standard. Analytical application of the method used has been established on the basis of statistical evaluation.     

Extraction of group VIII elements with 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5

The extraction of group VIII elements with 1-phenyl-3-methyl-4-trifluoracetyl-pyrazolone-5 from aqueous solutions in chloroform has been studied as a function of pH. Fe(III), Ni(II), Pd(II) and Rh(III) show partial extraction whereas Co(II) is extracted quantitatively. The effect of citrate, cyanide, fluoride, iodide, thiosulphate and thiourea on the extraction of metal ions has been investigated. Back-extraction studies were carried out to strip metal ions from organic phase into appropriate aqueous solutions. Based on these findings some useful analytical separations have been proposed and a few of their possible applications have been discussed.     

Solvent extraction of gold(III) with 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5

A simple, rapid and selective separation procedure of gold based on its extraction with 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5 has been developed. The dependence of the distribution ratio of gold on the pH of aqueous solutions, concentration of hydrochloric, nitric and perchloric acids and the organic solvents has been investigated. Decontamination factors for a number of metal ions with respect to gold are reported. Excellent separation of gold is obtained from many elements including noble metals. Citrate, cyanide, iodide, thiosulfate and thiourea completely mask gold, whereas oxalate does not interfere. Solutions of 1 M HCl, 0.2 M KCN, and the buffer of pH 0.8 readily strip gold from the organic phase. Some useful analytical applications of this procedure are discussed.     

MHD flow of nanofluids over an exponentially stretching sheet in a porous medium with convective boundary conditions

This article concentrates on the steady magnetohydrodynamic(MHD) flow of viscous nanofluid. The flow is caused by a permeable exponentially stretching surface. An incompressible fluid fills the porous space. A comparative study is made for the nanoparticles namely Copper(Cu), Silver(Ag), Alumina(Al2O3) and Titanium Oxide(TiO2). Water is treated as a base fluid. Convective type boundary conditions are employed in modeling the heat transfer process. The non-linear partial differential equations governing the flow are reduced to an ordinary differential equation by similarity transformations. The obtained equations are then solved for the development of series solutions. Convergence of the obtained series solutions is explicitly discussed. The effects of different parameters on the velocity and temperature profiles are shown and analyzed through graphs.     

Longitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulenceLongitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulenceLongitudinal and transverse structure functions in decaying nearly homogeneous and isotropic turbulence

Streamwise evolution of longitudinal and transverse velocity structure functions in a decaying homogeneous and nearly isotropic turbulence is reported for Reynolds numbers Re;t up to 720. First, two theoretical relations between longitudinal and transverse structure functions are examined in the light of recently derived relations and the results show that the low-order transverse structure functions can be well approximated by longitudinal ones within the sub-inertial range. Reconstruction of fourth-order transverse structure functions with a recently proposed relation by Grauer et al. is comparatively less valid than the relation already proposed by Antonia et al. Secondly, extended self-similarity methods are used to measure the scaling exponents up to order eight and the streamwise evolution of scaling exponents is explored. The scaling exponents of longitudinal structure functions are, at first location, close to Zybin＇s model, and at the fourth location, close to She-Leveque model. No obvious wend is found for the streamwise evolution of longitudinal scaling exponents, whereas, on the contrary, transverse scaling exponents become slightly smaller with the development of a steamwise direction. Finally, the stremwise variation of the order-dependent isotropy ratio indicates the turbulence at the last location is closer to isotropic than the other three locations.