Publications internationales
Résumé: An equation of state that predicts the critical thermodynamic behavior of n-butane isformulated. This equation takes into account the global behavior that includes the sin-gular thermodynamic behavior asymptotically close to the critical point and the crosso-ver to the regular thermodynamic behavior far away from the critical point. The formu-lated equation is based on the transformation of a truncated classical Landau expansionand represents the thermodynamic properties of n-butane in a wide range of tempera-tures and densities around the critical point. A comparison of the pressure P–ρ–T datameasured by Beattie and co-workers and those calculated with the crossover EOS ismade. Finally, the specific heat at constant volume, Cv, for n-butane along the criticaldensity within a restricted temperature interval around the critical point is presented (PDF) An Equation of State for the Thermodynamic Properties of Fluid n-Butane in the Critical Region. Available from: https://www.researchgate.net/publication/379694201_An_Equation_of_State_for_the_Thermodynamic_Properties_of_Fluid_n-Butane_in_the_Critical_Region#fullTextFileContent [accessed Apr 13 2024].
Résumé: Natural and fragrant compounds, essential oils (EOs) extracted from plants through hydrodistillation, are gaining popularity as eco-friendly and sustainable agents to protect metals and alloys from corrosion in acidic environments. This research focused on extracting and characterizing an EO obtained from the Cuminum cyminum (CC) plant native to India. The study aimed to evaluate the inhibitory properties of this EO on mild steel in a 0.5 M HCl solution at different concentrations. Various analytical techniques, including potentiodynamic polarization curves, electrochemical impedance spectroscopy, optical microscopy, infrared spectroscopy, and proton magnetic resonance, were employed to assess the effectiveness of this EO extract. Our findings indicate that the Cuminum cyminum L (CCL) extract effectively reduces the corrosion of mild steel in hydrochloric acid with an inhibition efficiency ranging from 79.69 to 98.76%. The optimal inhibition concentration was 2 g/L of EO, and surface analysis confirmed the formation of a protective layer. Furthermore, our results suggest that the inhibitor binds to the metal surface through a charge-transfer process, creating a protective film. Finally, we utilized theoretical calculations and molecular dynamics simulations to elucidate the inhibition mechanism on both a global and local scale.
Résumé: The study delves into the versatile applications of essential oils, natural aromatic compounds derived from plants through hydro-distillation or cold extraction, across industries such as cosmetics, fragrances, food processing, traditional medicine, and agriculture. Notably, these plant-derived compounds have gained prominence as corrosion inhibitors for metals and alloys in acidic environments. The research focuses on evaluating the inhibitory capacity of Suzygium aromaticuim on regular steel submerged in an acidic medium, employing various concentrations of essential oil (1.5 g/L to 6 g/L). The inhibitory effectiveness was evaluated using electrochemical techniques, including potentiodynamic polarization curves and electrochemical impedance spectroscopy. Electrochemical measurements and optical microscope analyses were used to examine the effect of cloves' essential oils on the corrosion resistance of mild steel in a 0.5 M HCl media. NMR and IR spectroscopy were used to learn about the two isolated chemicals (eugenol and β-caryophyllene). The corrosion-inhibiting properties of β-caryophyllene at 2 g/L in an acidic media were studied. Density functional theory (DFT) computations and molecular dynamics simulations were used to isolate the essential oil component of cloves responsible for the corrosion inhibition of mild steel. Inhibition effectiveness peaked at 94 % at 4 g/L, leading the researchers to infer that the natural substance is a mixed-type inhibitor. Optical microscope analysis confirmed the protection offered at the optimum concentration, while β-caryophyllene demonstrated noteworthy inhibitor efficiency, especially when compared to Eugenol. DFT analysis further supported the corrosion inhibition potential of β-caryophyllene in aggressive solutions.
Résumé: An equation of state that predicts the thermodynamic behavior of propane is formulated. This equation takes into account the global behavior that includes the singular thermodynamic behavior asymptotically close to the critical point and the crossover to the regular thermodynamic behavior far away from the critical point. The formulated equation based on the transformation of a truncated classical Landau expansion. This equation of state (EOS) can represent the thermodynamic properties of propane in a wide range of temperatures and densities around the critical point. Comparisons of the pressure P–ρ–T data measured by Mark Mclinden of NIST group calculated with crossover EOS and those computed by the EOS of Eric Lemmon and selected results of other experimentalists are presented, as well as the isochoric-specific heat data measured by Abdulagatov et al. of the Russian groups are presented. We also give the comparison with a set of isobaric-specific heat data of Yesavage et al. The description of the rectilinear diameter singularity near the critical point is also discussed.