Abdelmottaleb Ben Lamine

Statistical Physics Studies of Multilayer Adsorption on Solid Surface: Adsorption of Basic Blue 41 Dye onto Functionalized Posidonia Biomass

In this article, finite multilayer adsorption modeling was presented. The grand canonical formalism was used to establish a novel finite multilayer with multisite occupancy model. Expression for the physico-chemical parameters involved in the adsorption phenomena were derived based on statistical physics treatment. This model has been applied to one of the most challenging adsorption in liquid phase, i.e., Basic Bleu 41 dye adsorption onto raw and modified Posidonia biomass. The parameters involved in the analytical expression of the multilayer model such as the number of adsorbed molecules per site, the density of occupied receptor sites, and the number of adsorbed layers were determined by fitting the experimental adsorption isotherms at temperatures ranging from 303 to 353 K. Fitting results show that the dye molecules are multimolecular adsorbed onto Posidonia surface. Furthermore, the new approach leads us to quantify the mean number of adsorbed layers. The magnitudes of the calculated adsorption energy indicate that BB41 dye is physisorbed onto Posidonia adsorbent.

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

The adsorption equilibriums of binary mixtures of the 4-tert-butyl-1-propylpyridinium bromide (referred to IL1) and 4-tert-butyl-1-(2 carboxyethyl) pyridinium bromide (referred to IL2) ionic liquids and ibuprofen (2-(4-(2-methylpropyl) phenyl) propanoic acid: IBP) on activated carbon cloth were investigated. The binary adsorption isotherms of the studied systems (IL1/IL2, IL1/IBP and IL2/IBP) have been studied in different conditions (different temperatures ranging from 286 to 313 K and at various concentration ratios 0.5, 1 and 2). The experimental isotherms have been simulated by some new statistical physics models established from the grand canonical ensemble. According to the most appropriate model, the adsorbed ILs and IBP molecules are assumed to be parallel to the activated cloth surface. An inhibition effect has been observed between the adsorbed molecules. The determination of the monolayer adsorbed uptake at saturation has shown an endothermic adsorption process of IBP and an exothermic one of IL1 and IL2. The estimated energy values demonstrate a physical adsorption whatever the adsorbate species. The microscopic adsorption process was interpreted from the point of view of molecular stereography and interaction energy. Moreover, a conductor-like screening model for real solvents (COSMO-RS) has been applied to calculate three specific interaction energies between the adsorbate molecules and a graphene layer modeling the activated carbon surface, i.e., the electrostatic misfit energy (EMF), the hydrogen-bonding energy (EHB) and the van der Waals energy (EvdW).

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

Knowledge of the ibuprofen (IBP) adsorption isotherms is important to understand and to improve its depollution process. In this work, the double layer model with two energies was applied to simulate the adsorption isotherms of ibuprofen on raw activated and two chemically modified granular activated carbons, obtained experimentally at pH = 7 and at different temperatures (298, 313 and 323 K). The chemically modified samples were obtained by treatment at 700 °C under nitrogen flow and ultrasonic treatment in H2O2 solution of the raw granulated activated carbon. The establishment of the model is based on a statistical physics approach, particularly on the grand canonical ensemble. The double layer model with two energies for each layer was found to be the best model to describe the adsorption process of ibuprofen. Using this model, the different adsorption isotherms of ibuprofen were described sterically and energetically through these parameters. The different parameters were interpreted as a function of temperature. In addition to this, the entropy, free enthalpy and the internal energy governing the adsorption process were calculated and interpreted.

Adsorption thermodynamics in the framework of the statistical physics formalism: basic blue 41 adsorption onto Posidonia biomass

AbstractAdsorption isotherms have important practical applications, including in interface chemistry where they have been used to model adsorbate/adsorbent interactions. Basing on the grand canonical formalism in statistical physics, a finite multilayer model with multisite occupancy was established. The main purpose of that work was to predict some adsorption thermodynamic parameters. Here, the model is developed further to obtain expressions for the configurational entropy, S, the Gibbs free enthalpy, G and the Helmholtz free energy, F. These calculated thermodynamic parameters are used to interpret the adsorption process and the interactions of adsorbate with each other, as well as, with the adsorbent surface. In this paper, we show how the grand canonical formalism will be emphasized for treating more advanced adsorption model with thermodynamic study.

New insights on energetic analysis of water adsorption isotherms of the Pelargonium graveolens: modeling, interpretations and pore sizes distribution based on statistical physics approach

A new model for the adsorption isotherm of the Pelargonium graveolens leaves was established. The establishment of this model is based on the statistical physics formalism and some working hypotheses. In this model, six parameters affecting the adsorption process were adjusted, namely the number of molecules per site, the density of receptor sites, the three energetic parameters and the number of layers, and the model applied to calculate the specific area. These were determined by fitting the experimental adsorption isotherms at temperatures ranging from 303 to 323 K, and they were discussed and interpreted for their temperature dependence. After that, our model is used to calculate the adsorption energy distribution which implies that it is a physisorption, the internal energy which confirms that that the system evolves spontaneously and the distribution of the pore sizes, which presents that the geranium leaves samples studied with in the present work are macropores.

A statistical physics study of the interaction of [7]-helicene with alkali cations (K+ and Cs+): new insights on microscopic adsorption behavior

The adsorption of a metal ion to a polycyclic aromatic molecule such as helicene is the object of our study. The latter could function as a chiral molecular clamp for the cationic alkali metal. The main contribution of this work is to attribute new microscopic interpretations for the adsorption of potassium and cesium ions onto a thin layer of helicene achieved by the QCM technique. Throughout the grand canonical ensemble and some theoretical considerations, statistical physics processing has been used for modeling of experimental adsorption isotherms. A new model has been developed and chosen as an appropriate one to present a good correlation with experimental isotherms. Six physico-chemical parameters are obtained from the fitting of the experimental adsorption isotherms. Thanks to the steric parameters, we have found that an increase in temperature promotes a rise in the numbers of ions per site n1 and n2 and raises the adsorption capacities NM1 and NM2. The two energetic parameters c1 and c2 allow deduction of the adsorption energies at four temperatures. It is found from the calculated energies that physical adsorption takes place; the helicene can function as potassium and cesium captor and the K+–helicene complex is more stable than the Cs+–helicene complex.

Modeling of adsorption isotherms of reactive red RR-120 on spirulina platensis by statistical physics formalism involving interaction effect between adsorbate molecules

In this study, the formalism of statistical physics is used to describe and interpret the adsorption mechanism by applying the law of real gas which takes into account the interaction between the reactive red 120 dye (RR-120) molecules due to its very large size (approximately 2.11 nm). Modeling of the RR-120 dye adsorption isotherms on Spirulina platensis sp. is performed. Five models based on statistical physics formalism are developed: Hill model with one adsorbed site energy, Hill model with two energies, Hill model with three energies, double layer model with one energy and double layer model with two energies. These five models are treated alternatively with the ideal gas law (IG) and with the law of Ven Der Waals (VDW) real gas (RG). Fitting of six adsorption isotherms at different temperatures (298K, 303K,308K, 313K, 318K and 328K) is performed with, the pH fixed to 2. According to values of correlation coefficient, the Hill model with one energy and a VDW real gas interaction has been chosen as the adequate model to best fit the experimental data.

Stereochemical study of mouse muscone receptor MOR215-1 and vibrational theory based on statistical physics formalism

In the biosensor system, olfactory receptor sites could be activated by odorant molecules and then the biological interactions are converted into electrical signals by a signal transduction cascade that leads the toopening of ion channels, generating a current that leads into the cilia and depolarizes the membrane. The aim of this paper is to present a new investigation that allows determining the olfactory band using a monolayer adsorption with identical sites modeling which may also describe the static and the dynamic sensitivities through the expression of the olfactory response. Moreover, knowing the size of receptor site in olfactory sensory neurons provides valuable information about the relationship between molecular structure and biological activity. The determination of microreceptors and mesoreceptors is mostly carried out via physical adsorption and the radius is calculated using the Kelvin equation. The mean values of radius obtained from the maximum of the receptor size distributions peaks are 4 nm for ℓ-muscone and 6 nm for d-muscone.

Morphologic, Structural, Steric, Energetic and Thermodynamic Studies of the Mechanical Alloy Mg50Ni45Ti5 for Hydrogen Storage

The Mg50Ni45Ti5 alloy for the hydrogen storage is prepared by mechanical alloying. The structure and the morphology of the alloy are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). These techniques esteemed that this alloy is a good candidate for hydrogen storage, since it is both nanocristallin and dsuctile. This is confirmed by the modeling of the hydrogen equilibrium pressure-composition-temperature (PCT) relationships for this alloy. These isotherms were experimentally generated for three temperatures 313 K, 327 K and 340 K and modeled through the statistical physics using the monolayer model with two energies levels. Energetic, steric and thermodynamic studies were released thanks to this model which proved the efficiency and the security of this alloy to the storage of hydrogen.

Adsorption Energy and Pore-Size Distributions of Activated Carbons Calculated Using Hill's Model

An integral equation derived using a statistical physics treatment by considering the adsorption energy distribution (AED) was used to model the adsorption of ethylene and ethane on resorcinol–formaldehyde-based activated carbon xerogels. Hills model was taken as a local adsorption isotherm. This model was based on a grand canonical ensemble. Then a relationship between the energetic and the structural heterogeneities is used to determine the pore-size distribution (PSD) function. The AED and PSD obtained illustrate the greater affinity of activated carbon for adsorption of ethylene compared to ethane. In addition, this method was applied to determine the PSD of the British Drug House (BDH) activated carbon. The behaviour of the obtained PSDs at different temperatures was examined and related to the adsorption capacity of BDH activated carbon towards ethane, methane and nitrogen.