Modeling and Thermodynamic Study of Water Vapor Desorption Isotherms of Orange Peel and Leaves using Statistical Physics Treatment

The shelf life and safety of food products is related to the water content, in particular to the water activity (aw). This is important to predict the physical, chemical and biological processes that take place during food storage. Analytical expression for modeling water desorption isotherms of food is developed using the grand canonical ensemble in statistical physics. The model is further applied to fit and interpret the desorption isotherms of water vapor on the orange peel and leaves at three different temperatures. In the developed model we introduce essentially six parameters such as the number of adsorbed water molecules per site, the number of adsorbed layers, the energy of desorption and receptor sites density. We interpret the results of fitting then we apply the model to calculate thermodynamic functions which govern the desorption mechanism such as internal energy and entropy

Contribution à l'étude de la gustation des molécules sucrées à travers un processus d'adsorption. Modélisation par la physique statistique

L'adsorption des molécules sucrées sur les sites récepteurs du goût est une étape déterminante dans le mécanisme de la perception de la saveur sucrée. Naturellement, l adsorption se situe à la périphérie dans ce mécanisme. Nous avons réalisé des courbes de réponse psychophysique à l'aide d'un dispositif approprié nommé SMURF pour quatre molécules sucrées: le saccharose, le fructose, le glucose et le maltitol. Par l'intermédiaire de l'ensemble grand canonique un traitement de physique statistique a été utilisé pour le développement des expressions analytiques de la réponse gustative en terme d'adsorption. La modélisation nous a permis d'adopter le modèle double couche pour l'interprétation du phénomène d'adsorption. Les valeurs du nombre de molécules par site trouvées nous ont permis de déterminer le type d'ancrage pour chaque molécule selon la géométrie: un ancrage parallèle et un ancrage perpendiculaire. Nous avons trouvé une corrélation entre le pouvoir sucrant d'une part et l'énergie d'adsorption, la réponse maximale, la solubilité et le taux d'occupation à la concentration seuil d'autre part. En parallèle nous avons réalisé des isothermes d'adsorption du saccharose à l'aide d'une microbalance à quartz (QCM) sur trois couches minces de porphyrine, de calixarène et d'or. La modélisation de ces isothermes par le modèle de BET modifié nous a permis de caractériser l'adsorption à l'aide des paramètres physicochimiques du modèle. Nous avons montré que les nombres de molécules par site et les énergies d'adsorption sont proches de celles de la gustation. Le saccharose présente donc le même comportement sur ces supports que dans le mécanisme de perception du goûtAdsorption of sweet molecules on gustatory receptor sites is a determining step in the mechanism of taste chemoreception. Obviously adsorption is a peripheral event. A SMURF device (Sensory Measuring Unit for Recording Flux) is used to obtain experimental psychophysical curves relative to four sweeteners: sucrose, fructose, glucose and maltitol. Through the grand canonical ensemble a treatment of statistical physics is used to develop analytic expressions of the gustatory response in terms of adsorption. The modeling allowed selecting of the double layer model which is used to interpret the adsorption phenomenon. The variation of the number of adsorbed molecules per site permitted proposing of two types of anchorage of a sweet molecule to the adsorbent surface: the first consists in a parallel anchorage and the second is a perpendicular anchorage. We found out a relationship between sweetness potency of molecules and the physical parameters of the model. Hence, a correlation was found between sweetness potency on the one hand and the maximum response, the solubility, and the occupation rate at threshold concentration on the other. In parallel we carried out using a Quartz Crystal Microbalance (QCM) adsorption isotherms of sucrose on three thin layers of porphyrin, calixarene and gold. The modeling of the isotherms by the modified BET model allowed characterization of the adsorption using physicochemical parameters of the model. We showed that the number of molecules per site and the adsorption energies are similar to those of taste. So the sucrose presents the same behavior on these supports as in taste chemoreceptionREIMS-BU Sciences (514542101) / SudocSudocFranceF

Equilibrium isotherm simulation of tetrachlorethylene on activated carbon using the double layer model with two energies: Steric and energetic interpretations

In this paper, the adsorption isotherms of tetrachlorethylene (PCE) on activated carbon at different temperature were simulated and interpreted using the double layer model with two energies. The formulation of this model was based on statistical physics formalism. Steric and energetic parameters related to the adsorption process were introduced in this model, such as the number of molecules per site (n), the receptor sites density N-M and the concentrations at half saturation c(1) and c(2). These parameters were deduced by numerical simulation of the adsorption isotherms and interpreted at different temperatures. Thermodynamic functions of adsorption process, i.e., entropy, free enthalpy and internal energy were computed and their negative values indicate that the adsorption is exothermic and spontaneous

Application of statistical physics formalism to the modeling of adsorption isotherms of ibuprofen on activated carbon

International audienc

Binary adsorption isotherms of two ionic liquids and ibuprofen on an activated carbon cloth: simulation and interpretations using statistical and COSMO-RS models

International audienc

Experimental and theoretical studies of adsorption of ibuprofen on raw and two chemically modified activated carbons: new physicochemical interpretations

International audienc

Advanced green peel utilization for efficient methylene blue removal: Integrated analysis and predictive modeling

International audienceThis study explores the adsorption of Methylene Blue (MB) onto Green Peel (GP) material, utilizing advanced analytical techniques and modeling approaches. Fourier-transform infrared spectroscopy (FT-IR) confirms GP’s effectiveness as an adsorbent. The study systematically examines the influence of key factors such as adsorbent dose, pH, MB concentration, and temperature on adsorption efficiency. Among the isotherm models analyzed, the monolayer with double energy (M2) model is identified as the most accurate for describing MB adsorption onto GP. Steric parameters provide insights into the adsorption mechanism, revealing temperature-dependent changes. Thermodynamic analysis indicates an exothermic adsorption process, with a decrease in adsorption capacity at elevated temperatures. Density Function Theory (DFT) analysis highlights the potential for electron transfer during adsorption, contributing to a deeper understanding of the process. Molecular Dynamic Simulation (MDS) uncovers stable adsorption configurations and reveals the significance of chemical interactions and Van der Waals forces. Gaussian Process Regression with Lévy Flight Distribution (GPR_LFD) demonstrates exceptional predictive accuracy, closely aligning experimental and predicted MB uptake values. Optimal adsorption conditions (30 min contact time, 0.6 g adsorbent dose, 400 mg/L initial MB concentration, pH 6.6, and 10 °C) yield an adsorption capacity of 207.90 mg/g. The integration of LFD optimization and GPR prediction through a MATLAB interface further enhances the practical application of these findings. This comprehensive investigation not only advances the understanding of MB adsorption onto GP but also highlights GP’s potential as an efficient, reusable adsorbent

Mechanistic insights and steric interpretations through statistical physics modelling and density functional theory calculations for the adsorption of the pesticides atrazine and diuron by Hovenia dulcis biochar

International audienceAtrazine and diuron are two pesticide compounds with very low surface interaction capacity, whose adsorption efficiency remains a challenge in environmental remediation applications. In this work, statistical physics (sta-phy) modelling and density functional theory (DFT) calculations have explored several still unveiled mechanisms involved. A model activated carbon (AC) sample was produced with Hovenia dulcis fruit residues, a local invasive tree species. The adsorption process was spontaneous and endothermic, and the adsorption capacities () increased as the temperature increased. The number of adsorbate molecules per site (n) decreased as the density of the receptor site (Nm) increased, revealing that the temperature influences the geometry of the molecules during the surface interaction. According to the electrostatic mapping provided by the DFT calculations, it was possible to infer that the obtained Qm values for atrazine, between 42.54 and 73.20 mg g−1, can be a response caused by its own self-repulsion. For diuron, due to its increased neutrality, the potential balance of the electrostatic charges between adsorbate-adsorbent tends to be more effective, resulting in higher Qm values, ranging from 97.91 to 119.7 mg g−1. Therefore, the combination of sta-phy modelling with quantum mechanics calculations is a powerful tool for mechanism interpretation, capable of providing complementary insights into the adsorption process from both adsorbent and adsorbate perspectives

Steric and energetic interpretations of the equilibrium adsorption of two new pyridinium ionic liquids and ibuprofen on a microporous activated carbon cloth: Statistical and COSMO-RS models

International audienc