Studies on petroleum sulphonates: Correlation between their chemical structure and the oil—Water emulsion stability characteristics

The average molecular weight distribution, emulsion stability of oil—water emulsion, the chemical structure of the hydrocarbon portions of petroleum sulphonates, and surface active properties have been determined with a view to establishing a correlation between the chemical structure of petroleum sulphonates and their emulsion stability characteristics. It has been found that the emulsion stability of oil—water emulsions imparted by sodium petroleum sulphonates depends on: (i) average molecular weight of sodium petroleum sulphonates; (ii) their molecular weight distribution; (iii) oil—water interfacial tension; (iv) hydrophile—lipophile balance values. The structural parameters which predominantly effect the emulsion stability are the ratio of the percentage distribution of carbon atoms in paraffin side chains to the percentage distribution of carbon atoms, the aromatic rings (C_P/C_A), the relative proportions of long chain mono-aromatics and the orientation of the sulphonate group relative to the paraffin alkyl chains in the molecules.     

Synthesis of copper nanoparticles by electrolysis of DNA utilizing copper as sacrificial anode

Copper nanoparticles have been synthesized by anodic oxidation through a simple electrolysis process employing de-oxy ribonucleic acid (DNA) as electrolyte. Platinum was taken as cathode and copper as anode. The applied voltage was 4 V and the electrolysis was performed for duration of 1 h. The copper nanoparticles were prepared in situ from the electron beam irradiation on residues of electrolyte consisting of DNA and copper particles: DNA (Cu) complexes. The size of the nanoparticles ranges between 5-50 nm. A tentative explanation has been given for the formation of copper nanoparticles.     

Palm fatty acid biodiesel: process optimization and study of reaction kinetics

The relatively high cost of refined oils render the resulting fuels unable to compete with petroleum derived fuel. In this study, biodiesel is prepared from palm fatty acid (PFA) which is a by-product of palm oil refinery. The process conditions were optimized for production of palm fatty acid methyl esters. A maximum conversion of 94.4% was obtained using two step trans-esterification with 1:10 molar ratio of oil to methanol at 65°C. Sulfuric acid and Sodium hydroxide were used as acid and base catalyst respectively. The composition of fatty acid methyl esters (FAME) obtained was similar to that of palm oil. The biodiesel produced met the established specifications of biodiesel of American Society for Testing and Materials (ASTM). The kinetics of the trans-esterification reaction was also studied and the data reveals that the reaction is of first order in fatty acid and methanol (MeOH) and over all the reaction is of second order.     

Purification of tetrahydrofuran from its aqueous azeotrope by extractive distillation: Validation of model and simulation

Tetrahydrofuran (THF) purification by distillation is difficult due to the existence of its homogeneous, minimum boiling azeotrope with water. Previously conducted extractive distillation runs were used in this work to validate a rigorous model.

The validated model was then used to arrive at a feasible range of operating parameters by performing sensitivity analysis. It is shown through simulations that with the correct operating parameters, use of dimethyl sulfoxide can help obtain almost pure THF.     

Liquid Exfoliation of Icosahedral Quasicrystals

The realization of quasicrystals has attracted a considerable attention due to their unusual structures and properties. The concept of quasicrystals in the atomically thin materials is even more appealing due to the in‐plane covalent bonds and weak interlayer interactions. Here, it is demonstrated that 2D quasicrystals can be created/isolated from bulk phases because of long‐range interlayer ordered aperiodic arrangements. An ultrasonication‐assisted exfoliation of polygrained icosahedral Al–Pd–Mn quasicrystals at room temperature shows the formation of a large area of mono‐ and few layers in threefold quasicrystalline plane. The formation of these layers from random grain orientation consistently indicates that the threefold plane is most stable in comparison to the twofold and fivefold planes in icosahedral clusters. The above experimental observations are further supported with help of theoretical simulations. The mono‐ and few‐layered aperiodic planes render plentiful active sites for the catalysis of hydrogen evolution reaction. The threefold 2D quasicrystalline plane exhibits a hydrogen evolution reaction overpotential of ≈100 mV (160 times less than bulk counterpart) and long‐term durability. These systems constitute the first demonstration of quasicrystalline monolayer ordering in a free‐standing thin layer without requiring the support of periodic or aperiodic substrate.     

Unsupervised hyperspectral band selection using ranking based on a denoising error matching approach

In this paper, we focus on utilizing the image denoising method for ranking of significant bands in hyperspectral imagery. We make use of the fact that the denoising error of bands varies with the significant information content of the bands in hyperspectral imagery. The denoising error is computed for each band individually and compared using a matching parameter with the denoising error of a reference image. The reference image is selected to be the first principal component corresponding to the maximum information. Three matching parameters including mutual information (MI), correlation coefficient (r) and the structural similarity index (SSIM) were used for ranking the bands based on the match with the denoising error of the reference image. The proposed algorithm is tested using three datasets, namely, Indian Pines, Salinas and Dhundi. The Indian Pines and Salinas datasets were acquired from the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) sensor and comprised rural and agricultural area. The Dhundi dataset of Hyperion comprises mostly of features corresponding to snow-covered mountainous regions. To assess the accuracy of the proposed method, a supervised classification was carried out using a random forest classifier with 20% training pixels selected randomly from the ground reference. The proposed method yielded significantly better results determined by the kappa coefficient (κ) of 0.756, 0.910 and 0.996 for the Indian Pines, Salinas and Dhundi datasets, respectively, over several other state of the art methods. The classification results of the proposed method also yielded better results than those obtained by the state-of-the-art methods for hyperspectral band selection.     

Theoretical study of temperature induced transition and hyper stability of collagen mimics

Collagen a polymer, is the nature's most abundant protein. It has an immense tensile strength and is the main constituent of ligaments, tendons, etc. The present communication interprets the experimental data of thermally induced transition in collagen mimics as reported by Steven K. Holmgren and co-workers. The theoretical transition curves as obtained by the modified Zimm and Bragg model are found to be in good agreement with the experimental data. The order of the values of nucleation parameter and enthalpy changes obtained theoretically, attributes the increase in the degree of the stability of collagen mimics [(Pro-Pro-Gly)₁₀〈(Pro-Hyp-Gly)₁₀〈(Pro-Flp-Gly)₁₀].     

Designing Absorption Processes with Aqueous Diglycolamine

2‐(2‐Aminoexthoxy)ethanol or diglycolamine (DGA) is a CO₂ absorption solvent that is suitable to treat natural gas, flue gas, and biogas or landfill gas. Equilibrium CO₂ solubility in concentrated aqueous DGA solvents with varying molality was measured under absorption and desorption conditions at different temperatures. Viscosity and surface tension of the solvent before absorption, after absorption, and after desorption were determined. With increasing DGA molality, CO₂ loading remained constant until the number of moles of DGA exceeded the number of moles of water. For a given DGA molality, with higher CO₂ loading, viscosity increased exponentially and surface tension rose with a power of two.