Use of inverse gas chromatography to account for the pervaporation performance in the microemulsion breakdown

Mass transfer phenomenon that occurs in the pervaporation process when applied to the microemulsion breakdown, was confirmed by the results of inverse gas chromatography. The stationary phase for this study was polydimethylsiloxane (PDMS), a hydrophobic polymer employed as a membrane in the pervaporation technique. The retention times of the different molecule probes (toluene, cyclohexane, and n-butanol) gave an insight into the extent of the interactions between each of these molecules and the stationary phase; these molecules were the components of the two microemulsions in study. The infinite dilution conditions allowed to determine the thermodynamic and the chromatographic parameters γ∞ (the infinite dilution activity coefficient), the Flory-Huggins parameter interactions χ∞12, and V0g (the specific retention volume), respectively. The magnitudes of the latter parameters threw some light on the permselectivity of the membrane in the pervaporation operation

Microemulsion breakdown by pervaporation technique: Effect of the alkyl chain length of n-alkanol, a cosurfactant of the microemulsion

Two sets of microemulsions, cyclohexane- and water-rich ones, were prepared with the following n-alkanols as cosurfactants: n-propanol, n-butanol, n-pentanol, and n-hexanol. The results showed the influence of the alkyl chain length of the n-alkanol on the permselectivity properties of the pervaporation technique in the breakdown of the microemulsions. The variations of the total flux rate J and the enrichment factor β were in parallel with the effect of the cosurfactant on the swelling extent of the PDMS membrane

Instances of mixed buckling and post-buckling of steel RHS beams

Simply supported steel beams with rectangular hollow section (RHS) are investigated, taking into account large twist and cross-sections distortions. A closed-form expression for the critical value of the external couple inducing lateral torsional buckling is found; homotopy perturbation method (HPM) is used to investigate the post-buckling non-linear path. The linear and non-linear paths given by HPM are compared to those of: i) a Newton–Raphson algorithm with arc length; and ii) the commercial FEM code Abaqus. Some numerical examples are presented

Ozone generation in a wire-to-cylinder corona discharge ozonizer fed with mixtures of O2 and N2

The generation of ozone in a coaxial wire-cylinder corona discharge reactor has been experimentally investigated using variable proportions (5% to 90%) of oxygen in nitrogen. The experiments have been carried out under negative polarity and using different gas flow rates (50 cm3/min to 200 cm3/min). The obtained results show that the corona current exhibits a certain dependence with the percentage of oxygen in the gas mixture, which may influence the rate of ozone production. Moreover, the evaluation of the ozone yield has revealed a non-linear dependence of this magnitude with the concentration of oxygen. The maximum ozone yield was obtained when the percentage of oxygen in the gas mixture was about 70%

Regeneration of transformer insulating fluids using membrane separation technology

Oxidation of oil/paper insulation initiates premature aging and introduces carboxylic acids with eventual increase in oil acidity, which hampers the properties of the oil. In this paper, a membrane separation technology-based purification process for aged insulation oil has been evaluated and reported. The intent of the present study is to eliminate carboxylic acids, dissolved decay contents and other colloidal contamination present in aged oil and enhance the useful life of oil. The potential of the membrane treatment process has been demonstrated using Ultraviolet Visible Infrared Spectroscopy and Fourier Transform Infrared Spectroscopy diagnostic measurements for oil and membrane. Additionally, membrane retention properties like membrane flux, retention coefficient, sorption time and membrane mass have been analyzed to understand the treatment process. To further evaluate the performance of the membrane and effectiveness of the treatment process, acidity, dielectric dissipation factor, relative permittivity, and resistivity measurements of the oil before and after filtration have been also reported. The proposed membrane purification method has been tested for Algerian utility in-service oil samples. It is inferred that, membrane filtration method is a simple and effective method for treatment of aged oils and aids in extending the remnant life of the oil. The procedure is economically attractive because of increasing prices for transformer liquids, cost effective and environmentally sounds

Influence of the hydrocarbon chain length of imidazolium-based ionic liquid on the dispersion and stabilization of double-walled carbon nanotubes in water

Imidazolium-based ionic liquids with a long hydrocarbon chain 1-methyl-1-ethanol-2-alkyl-imidazolium iodide ([M-E-Cn-Im] I, n = 13, 15 and 17) were used for the dispersion of DWCNTs in water.DWCNTs suspensions obtained were stable for more than a month, and no sedimentation was observed.The stability of the suspensions was investigated (measurement of optical density, zeta potential, parti-cle size, viscosity, and TEM images). Monitoring of the absorbance by UV/vis spectrophotometry for 20days showed that at low concentration (1 mM), the best suspension was obtained with the ionic liquid([M-E-C15-Im] I). At higher concentration (10 mM), the dispersion efficiency increased with the length ofthe hydrocarbon chain. This could be explained by the hydrophobic interaction between the hydrophobicmoieties of the ionic liquid and the CNTs. Therefore, we were able to stabilize DWCNTs using a low con-centration (1 mM) of imidazolium-based ionic liquids synthesized from natural compounds. This workhighlights the potential of imidazolium-based ionic liquids for the preparation of aqueous suspensionsof DWCNTs at high concentration with a limited amount of added surfactant (50 mg/L of DWCNTs with50 mg/L of ionic liquid)

Comprehensive Analysis of Phytochemical Composition, Antioxidant Potential, and Antibacterial Activity of <em>T. polium</em>

\ua9 2024 by the authors.This study aims to thoroughly examine the chemicals and effects of the ethanol extract from T. polium’s upper parts. We used the Soxhlet method for extraction, resulting in an extract with a significant yield of 20.6%. Qualitative analysis identified a variety of compounds, such as tannins, saponins, reducing compounds, terpenoids, quinones, and alkaloids. In quantitative analysis using the colorimetric method, we found the extract was rich in total flavonoids (20.78 mg equivalent QE/g DW extract) and total polyphenols (227.43 mg equivalent GAE/g DW extract). To assess antioxidant potential, we used the ferric reducing antioxidant power (FRAP) method, with ascorbic acid and butylated hydroxytoluene (BHT) as standards. The extract showed moderate activity in both the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and FRAP methods at concentrations of 65 \ub5g/mL and 21 mg/mL, respectively. Additionally, we tested the ethanolic extract against various bacteria using the disk diffusion technique on agar medium. The results indicated that the T. polium extract had moderate effectiveness against Gram-negative bacteria like Pseudomonas aeruginosa ATCC 9027 and Escherichia coli ATCC 8739, as well as Gram-positive bacteria like Staphylococcus aureus ATCC 6538 and Bacillus subtilis ATCC 6633. We further investigated the composition of the ethanolic extract through LC-MS/MS analysis, establishing a detailed profile of phenolic compounds, with six flavonoids identified as the main polyphenolic constituents. This thorough evaluation provides insights into the potential therapeutic uses of T. polium

Formulation and Optimization by Experimental Design of Low-Fat Mayonnaise Based on Soy Lecithin and Whey

The main objective of this study is to develop a new formula for a diet mayonnaise-like sauce without cholesterol. Emulsifying power is provided by the use of soy lecithin and the total fat content was limited to 16%. Droplet size measurement of employed mayonnaise samples at different times show that the largest diameter of fat does not exceed 18.5 µm with a yield stress of 56.1 Pa. Results of stability to centrifugation reveal that the absence of the supernatant oily layer ensures the stability of the emulsion. Using the experimental design method, the number of trials can be limited to a number of 16 experiments, and best formulation of the mayonnaise (without cholesterol) was obtained