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The main purpose of this research is to theoretically investigate the adsorption of two pharmaceutical molecules, i.e. aspirin and paracetamol, using two composite adsorbents, i.e. N-CNT/β-CD and Fe/N-CNT/β-CD nanocomposite polymers.

Water contaminants due to industrial organic dyes are posing serious human health and environmental problems. Adsorption technology has been widely used in wastewater remediation because of its simplicity, low cost, high effectiveness, and potential to use eco-friendly, non-toxic materials. Herein, the work presents an experimental and theoretical study of the adsorption process of Methylene Blue (MB) dye onto new biogenic copper oxide nanoparticles (CuO NPs) from Ephedra Alata plant extract. The CuO NPs were synthesized via a green chemistry approach and characterized by FE-SEM, EDXS, TEM, XRD, UV–Visible, FTIR, and Raman spectroscopies. The biosynthesized CuO-NPs present a large surface area, nanosize, and a monoclinic structure with phenolic, flavonoid, and hydroxyl groups on the surface. Adsorption tests were carried out under optimal conditions such as pH (7), dye concentration (10 mg/L), and adsorbent dose (0.02 g) to remove the most methylene blue dye from the solution. Adsorption isotherms showed that the capacity of MB adsorbed onto the biosynthesized CuO-NPs increased to 110 and 133.75 mg/g by increasing the temperature to 293 and 323 K, respectively. These experimental data were modeled using statistical physics theory in order to describe the steric and energetic factors involved in the removal of dye, as well as the adsorption mechanism. The modeling analysis demonstrated that MB adsorbed on the CuO-NPs adsorbent surface in a non-parallel orientation. Additionally, the investigated showed the energies of adsorption less than 40 kJ mol− 1. According to adsorption energy values, this mechanism progresses by physical adsorption. In summary, green synthesized CuO-NPs are potential materials for organic chemical removal from wastewater treatment.

This work describes the modeling and analysis of methylene blue molecule on different adsorbents, namely, nickel alginate/graphene oxide (NA/GO) aerogel, nickel alginate/activated carbon (NA/AC) aerogel, and Trichosanthes kirilowii maxim shell activated carbon (TKAC). A multilayer statistical physics model was used to calculate the energetic and steric parameters of the adsorption of methylene blue on these adsorbents. Based on the modeling investigation, it was concluded that the formation of multiple dye adsorbed layers on these adsorbents could be feasible where physical adsorption interactions could be involved. Adsorption capacities at saturation of these adsorbents ranged from 542.97 to 470.03 mg/g, 790.66 to 684.47 mg/g, and 401.11 to 1236.24 mg/g for NA-GO aerogel, NA-AC aerogel, and TKAC, respectively. This research contributes with new findings for the understanding of dye adsorption on novel materials, which can be used in water pollution control.

An activated carbon (AC) deriving from sludge is used in this research for the adsorption of two water pollutants, namely Reactive Black 5 (RB5) and Green Alizarin (GA) dyes, at different temperatures. The adsorption capacities varied from 277.2 to 312.69 mg/g for GA and from 225.82 to 256.02 mg/g for RB5. Comparatively, this adsorbent presents good performances in removing these dyes from wastewater. The application of physical models to adsorption experiments is advantageous to provide new insights into the dyes' adsorption mechanism. A dedicated physical adsorption model suggests that RB5 and GA dyes are adsorbed in a monolayer. Moreover, the orientation of RB5 and GA dyes on AC resulted in an angled position, determining a multi-molecular process. In addition, both dyes are adsorbed by the occurrence of an aggregation process, forming a dimer. The impact of temperature can be also interpreted, allowing concluding that it plays a relevant role in removing these dyes. The calculation and interpretation of adsorption energies show that the dyes are removed via an endothermic process, and physical forces are involved.

Understanding olfaction process at a microscopic or molecular level needs more elucidation of the multiple stages involved in the olfaction mechanism. A worth full elucidation and a better understanding of this molecular mechanism, a necessary preamble should be achieved. The content of this work is a preamble for that. A study of the mouse and human olfactory receptors activation in response to two nitro musks stimuli, which are the musk xylol and the musk ketone, are considered here, first, for their wide expanded use in perfumery, but also to show some particular aspects of this process in the case of these two stimuli, which could help to deduce more details and more general aspects in the global olfactory mechanism. A statistical physics modeling using the monolayer model with two independent types of receptor binding sites of the response of the mouse olfactory receptor MOR215-1 and the human olfactory receptor OR5AN1, which are identified as specifically responding to musk compounds, is used to characterize the interaction between the two nitro musk molecules, the mouse and the human olfactory receptors and to determine the olfactory band of these two odorants through the determination of the molar adsorption energies and the adsorption energy distributions. The physico-chemical model parameters can be used for the steric characterization via the calculation of the receptor site size distributions. The docking computation between these two nitro musks and the human olfactory receptor OR5AN1 is performed demonstrating a large similarity in receptor-ligand detection process. Thus, docking finding results prove that the calculated binding affinities were belonging to the spectrum of adsorption energies.

In this work, two experimental dose-response curves of lyral molecules on the OR10J5 and the Olfr16 were employed in order to examine the evolution of physico-chemical parameters involved in the selected statistical physics model(s) to investigate the human and the mouse smelling of a floral scent. Indeed, one layer adsorption model on one type of sites with one energy (1LAM1T1E) and one layer adsorption model on two types of sites with two energies (1LAM2T2E), considered as appropriate models for the adsorption of lyral molecules on the OR10J5 and Olfr16, respectively, have been applied to fit the experimental data. Stereographic and energetic physico-chemical parameters, namely: the maximum response(s) at saturation, the number of docked molecules per olfactory receptor binding site and the concentration(s) at half saturation, were investigated to retrieve helpful information to describe the adsorption process putatively introduced in the olfaction perception. Thus, the advanced modeling results indicated that the studied molecules were docked with a non-parallel orientation (n 1). Furthermore, for the two olfactory systems, the molar adsorption energies estimated from curves modeling were inferior to 11 kJ/mol, which showed the physisorption process of the adsorption of lyral molecules on OR10J5 and Olfr16. The 1LAM2T2E and the 1LAM1T1E were applied to estimate the OR10J5 and the Olfr175 RSDs, respectively. Hence, lyral RSDs were spread out from 0.7 to 20 nm with maximums at about 4 nm for OR10J5 and at about 3.65 nm for Olfr16. In addition, by using the two advanced models, the olfactory responses of lyral on OR10J5 and Olfr16 can be used for the energetic characterization of the lyral-OR10J5/Olfr16 binding sites interactions and allowed access to the adsorption energy distributions (AEDs). Then, two approximate olfactory bands can be determined for lyral molecules docked on OR10J5 and Olfr16, which are defined between 3 and 15.5 kJ/mol and between 3.5 and 13.5 kJ/mol, respectively. Lastly, thanks to the proposed models the adsorption entropy of the studied systems can be calculated to describe the disorder and the order on OR10J5 and Olfr16 surfaces (disorder peak of the two olfactory systems was attained when the equilibrium concentration was equal to the concentration at half saturation). Furthermore, the Gibbs free enthalpy and the internal energy were estimated and their negative values indicated that the adsorption phenomenon involved in the olfactory perception was spontaneous and exothermic nature.

The investigation of the adsorption process putatively involved in the olfactory perception of apocynin, guaiacylacetone, homovanillyl alcohol, 4-ethylguaiacol and homoguaiacol molecules on the mouse eugenol olfactory receptor mOR-EG was a very useful tool for comprising olfaction process at a molecular level. Indeed, the experimental data were correlated by using an advanced monolayer adsorption model with identical and independent binding sites. Thanks to the grand canonical ensemble in statistical physics formalism, the physico-chemical interpretations of modeling results indicated that the five odorants were adsorbed via a multi-molecular mechanism. Hence, the calculation of adsorption energies, that described the interaction between the odorant molecules and the olfactory receptor binding cavities, indicated that weak bonds were made between apocynin, guaiacylacetone, homovanillyl alcohol, 4-ethylguaiacol and homoguaiacol molecules and mOR-EG binding pockets amino acid residues. In addition, theoretical stereographic and energetic characterizations of mOR-EG were made via the determination of the olfactory receptor site size distributions (RSDs) and the adsorption energy distributions (AEDs) relative to apocynin, guaiacylacetone, homovanillyl alcohol, 4-ethylguaiacol, homoguaiacol molecules. The RSD provided the size of different binding cavities of mOR-EG. Indeed, the five RSDs spectrums situated between 0.5 and 10 nm were spread out around an average size each one. The mean values obtained from the peaks of the distributions were 2.14 nm, 2.20 nm, 2 nm, 2.10 nm and 1.83 nm for apocynin, guaiacylacetone, homovanillyl alcohol, 4-ethylguaiacol and homoguaiacol molecules, respectively. The AED gave a whole spectrum of adsorption energies that was activated by the odorant molecule. Thus, the apocynin, guaiacylacetone, homovanillyl alcohol, 4-ethylguaiacol and homoguaiacol AEDs were spread out from 5 to 27.5 kJ/mol, from 5 to 30 kJ/mol, from 5 to 35 kJ/mol, from 0 to 22.5 kJ/mol, 5 to 25 kJ/mol, respectively. The thermodynamic study, via the establishment of the adsorption entropy, indicated that the peak of the disorder was obtained when half of the binding sites were occupied. In addition, the Gibbs free enthalpy and the internal energy were determined and their negative values indicated that the adsorption phenomenon involved in the olfactory perception was spontaneous and exothermic physisorption phenomenon.

To obtain good economic and environmental benefits, LaMgNi3.6M0.4 (M = Al, Mn, Ni, Co, Cu) alloys are investigated for the hydrogen storage. The absorption data of hydrogen in the tested alloys are measured experimentally at 373 K. The hydrogen absorption isotherms are analyzed using three models derived from statistical physics formalism. The adequate model permits to discover significant details about the absorption phenomenon via determining the density of the interstitial sites (Dm), the number of hydrogen atoms per site (n) and the energetic parameter ΔE. The results indicate that multi-atomic (n > 1) and multi-linking (n

A theoretical physicochemical and thermodynamic investigation of the adsorption of heavy metals Zn2+, Cd2+, Ni2+, and Cu2+on carbon-based adsorbents was performed with statistical physics fundaments. Particularly, the experimental adsorption isotherms of heavy metal removal, at 30°C and pH 5, using adsorbents obtained from the pyrolysis of three biomasses (cauliflower cores, broccoli stalks, and coconut shell) were modelled and interpreted with a homogeneous statistical physics adsorption model. Calculations indicated that the heavy metal adsorption with these carbon-based materials was a multi-ionic process where several ions interact simultaneously with the same carboxylic functional group on the adsorbent surface. Adsorption capacities for these metal ions and adsorbents were correlated with electronegativity theory, which established that the adsorbate with the highest electronegativity was more readily adsorbed by the carboxylic functional groups available on the adsorbent surfaces. Also, the chemical compositions of biomass precursors explained achieved adsorption capacities for these metallic ions. The best adsorbent for heavy metal removal was obtained from CC biomass pyrolysis. Calculated adsorption energies for heavy metal removal could be associated with physisorption-type forces. Finally, the adsorption mechanism analysis was complemented with the determination of adsorption thermodynamic functions using the statistical physics.

Thermodynamic, energetic, and stereographic parameters controlling the acetylene adsorption on (0001) exfoliated graphite were determined. The results showed that statistical physics model 2 (monol...

The simultaneous adsorption of three pollutants cobalt (Co), methylene blue (MB) and nickel (Ni) on a modified chitin surface from ternary systems was investigated. Multicomponent experimental adsorption data were determined at 298–328 K and pH 6. These experimental studies indicated that Ni adsorption was higher than those obtained for Co and MB. The multicomponent adsorption mechanism of this ternary system was analyzed with statistical physics theory where a set of new models with different hypotheses was developed and tested. Results showed that an adsorption model assuming that the pollutants Co, MB and Ni were adsorbed on three different types of modified chitin receptor sites was the most appropriate. This model was also utilized to calculate the corresponding adsorption energies to describe the possible interactions between these adsorbates and the surface of modified chitin. A general analysis of trends and magnitude of the model parameters provided a deeper understanding of the ternary adsorption mechanism at molecular level. Macroscopically, the ternary adsorption mechanism was interpreted via a calculation of three thermodynamic functions.

In this paper, we consider two different polyethylene filter plates coated with multi-walled carbon nanotubes (MWCNTs) and synthesized by surface molecularly imprinted technique, namely plate@MWCNTs@MIPs (PMIPs) and plate@MWCNTs@NIPs (PNIPs). They were used as effective adsorbents for selective adsorption and detection of prednisone (PS) in cosmetics. As a first assessment to investigate the performance of these adsorbents, the PS adsorption isotherms were analyzed using an advanced multilayer statistical physics model at three different temperatures ( 293, 303 and 313 K) and over a wide PS concentration range (0.09–1.5 mg/mL). The obtained analyzing results from the best fitting model showed that the PMIPs adsorbent displayed a high adsorption capacity (27.4 mg/g) due to the contribution of the number of PS molecules per site (nm) combined with the receptor sites density (Dm), which displayed a high recognition ability due to the adsorption energy. Modeling analysis process indicated that the PS molecules could be anchored on the PMIPs and PNIPs surfaces via a non-parallel orientation where the adsorption is a multi-molecular process. The calculated adsorption energies globally varied from 4.51 to 7.62 kJ/mol, confirming the physical nature of the adsorption process for the studied systems, which is beneficial in cosmetics. Finally, three thermodynamic potentials (entropy, internal energy and free enthalpy) were evaluated for a better understanding of the physico-chemical behavior of the adsorption process.

The adsorption isotherms of Reactive Red 120 (RR-120) on Brazilian pine-fruit shell activated carbon, at six temperatures (298, 303, 308, 313, 318 and 323 K) and pH = 6, were determined and interpreted using a double layer model with one energy. A statistical physics treatment established the formulation of this model. Steric and energetic parameters related to the adsorption process, such as the number of adsorbed molecules per site, the receptor sites density and the concentration at half-saturation, have been considered. Thermodynamic potential functions such as entropy, internal energy and Gibbs free enthalpy are analyzed, and the choice of the models is based on assumptions in correlation with experimental conditions. By numerical fitting, the investigated parameters were deduced. The theoretical expressions provide a good understanding and interpretation of the adsorption isotherms at the microscopic level. We believe that our work contributes to new theoretical insights on the dye adsorption in order to know the physical nature of the adsorption process.

This study reported the combination of advanced statistical physics modeling and density functional theory (DFT) investigation for the interpretation of the adsorption of Paprika dye on TiO2 surface for dye sensitized solar cells. By using a statistical physics modeling method, an adequate monolayer model with four energies was successfully used to interpret the adsorption process at a macroscopic level. The DFT simulation has been used to study the interaction of the Paprika dye on TiO2 surface to understand some of the atomistic details that are crucial to the dye/semiconductor interaction. We pay particular attention to the adsorption modes, geometries and energies between the paprika dye and TiO2. The DFT simulation determined different binding modes which participated in the adsorption of Paprika dye on TiO2 surface: monodentate coordination via hydrogen atom bond, monodentate coordination via oxygen atom bond and bidentate coordination via two oxygen atoms bond. In particular, calculations showed that the interaction between the paprika dye and TiO2 is strengthened with the bidentate coordination mode via the two hydroxyl and ether functionalities groups involved in the adsorption process. Keywords: Paprika oleoresin dye, Statistical physics modeling, DFT simulation, Adsorption isotherms, Dye sensitized solar cells

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The paper describes a theoretical analysis of the adsorption of nicotinamide and propranolol onto a magnetic-activated carbon (MAC). For a better evaluation of the adsorption mechanism, adsorption isotherms expressing the variation of the adsorption capacity as function of adsorbate concentration were determined at different temperatures ranging from 20 to 45 °C. For both the analytes, experimental tests reveal that adsorption capacity increases with temperature. An advanced multi-layer model derived from the statistical physics is set for the interpretation of the entire adsorption data set. The modelling results show that the propranolol molecules change their adsorption orientation from a mixed (parallel and non-parallel) orientation to a multimolecular process. For nicotinamide, the aggregation of molecules is practically absent, except for the data at lower temperatures. The model allows stating that the adsorption of both the pharmaceutical compounds occurs via the formation of one or two layers on MAC adsorbent, the propranolol showing a higher tendency to form multiple layers. Finally, adsorption energy is estimated suggesting that the adsorption is endothermic and physical interactions are the responsible of the adsorption of both the compounds onto MAC adsorbent.

The work reports a modeling analysis of single-compound and binary adsorption of Pb2+ and Cd2+ ions from polluted water onto the activated carbon at room temperature. The homogeneous model for single adsorption (HM) and the exclusive extended monolayer model for binary adsorption (EEMM) are applied for the interpretation of the experimental data set. The adopted models correlate the entire set of adsorption data, allowing a thorough description of the occurring phenomena. The overall objective of the study is to determine the adsorption mechanisms, also through a comparative analysis between the single-compound and binary modeling data. The parameters of both models are used for to retrieve useful indications about the adsorption of these two ions. In particular, the number of ions adsorbed per single functional groups changed from single-compound to binary adsorption, allowing to explain the competitive behavior of the investigated system. The adsorption energy values vary between 21.39 (Pb2+) and 24.06 kJ/mol (Cd2+), and 27.17 (Pb2+) and 32.59 kJ/mol (Cd2+) in single-compound and binary systems, respectively, indicating that adsorption is a physisorption process.

A heterogeneous monolayer model with two types of binding site was utilized to analyze and interpret the adsorption mechanism of Fe3+, Al3+ and Cu2+ ions on chitosan films at 25–55 °C and pH 6. Theoretical results of statistical physics calculations indicated that the adsorption of Fe3+, Al3+ and Cu2+ ions was multi-ionic where two adsorption sites (i.e., amino and hydroxyl groups) were involved but with a different contribution degree. Adsorption capacities at saturation ranged from 125.99 to 512.27 mg/g for tested operating conditions. The removal mechanism of Al3+ and Cu2+ ions was exothermic, whereas the adsorption of Fe3+ ions was endothermic.

This research work is a contribution to understand the olfaction mechanism at a molecular level of vanillin, ethyl vanillin, coumarin and quinoline molecules using a modeling of a putative adsorption process by analytical model established by statistical physics formalism. A statistical physics modeling using the monolayer model with identical and independent binding sites of the responses of the two human olfactory receptors OR10G4 and OR2B11 showed that vanillin and quinoline were adsorbed with a mixed non-parallel and parallel orientation on OR10G4 and on OR2B11, respectively. However, ethyl vanillin and coumarin were anchored with a total non-parallel orientation. The adsorption energy values collected from data analysis, which were ranged from 12.51 to 20.91 kJ/mol, confirmed that the adsorption of vanillin and ethyl vanillin on OR10G4 and the adsorption of coumarin and quinoline on OR2B11were exothermic and were based on physical interactions. Furthermore, the dose-olfactory response curves of vanillin, ethyl vanillin, coumarin and quinoline provided access to OR10G4 and OR2B11 steric characterization via the calculation of the studied olfactory receptors site size distributions (RSDs). Indeed, vanillin, ethyl vanillin, coumarin and quinoline RSDs are spread from 0.3 to 12 nm, from 0.5 to 12 nm, from 0.40 to 12 nm and from 0.14 to 12 nm, respectively, with a maximum at 1.55 nm, 2.11 nm, 2.50 and 1.13 nm, respectively. Lastly, the physico-chemical model parameters can be used for the energetic characterization to confirm the physical nature of the vanillin/ethyl vanillin-OR10G4 and the coumarin/quinoline-OR2B11 interactions and to determine an olfactory band of order of 12 kJ/mol [11–23 kJ/mol], 10 kJ/mol [14–24 kJ/mol], 7 kJ/mol [9–16 kJ/mol], 15 kJ/mol [13–28 kJ/mol] for vanillin, ethyl vanillin, coumarin and quinoline, respectively, through the determination of the adsorption energy distributions (AEDs).

Statistical physics formalism is used for modeling and interpreting the adsorption isotherms of the ions Cu(II) and Ni(II)-Spirulina system. Numerical modeling is performed at three temperatures (298, 318 and 338 K) and pH = 6. Cu and Ni adsorption isotherms were fitted by multilayer model and Hill model with two energies, respectively. The interpretations were based on the numbers of ions per site (n, n1, n2), the densities of receptor sites (Sm, S1m, S2m), the number of adsorbed layers N2 and the energetic parameters (C1, C2). The thermodynamic study indicated that the adsorption was spontaneous, exothermic for Cu and endothermic for Ni.

The adsorption of indium (III) on raw, supercritical- and ultrasound-modified chitin was experimentally and theoretically studied. Experimental adsorption data demonstrated that the profile of all adsorption isotherms was different from a system to another. Indeed, the adsorption behavior of the systems indium (III) – chitin and indium (III) – supercritical-modified chitin tended to a saturation process at high concentration thus suggesting that the adsorption can be occurred by the formation of a fixed number of adsorbate layers. Contrary to this finding, the adsorption of indium (III) on an ultrasound-modified chitin can be associated to a variable number of layers involving two adsorption energies. Statistical physics models were selected to understand the adsorption data and they demonstrated that the adsorption of indium (III) – chitin and indium (III) – supercritical-modified chitin was achieved by the formation of one layer; while the adsorption of this adsorbate on an ultrasound-modified chitin was performed with a variable number of layers. Based on the modeling analysis, it was demonstrated that the ultrasonic treatment improved the properties of chitin to remove this pollutant: Qesat of ultrasound-modified chitin > Qesat of supercritical-modified chitin > Qesat of raw chitin. The interpretation of parameter n, which is defined as a number of bonded ions of indium (III) per responsible site of the adsorbent, was higher than 1 at high temperature. This result suggested that the indium adsorption was a multi-ionic mechanism. All adsorption systems were characterized by an estimation of the adsorption energy reflecting that the removal of this pollutant involved physical interactions. A general analysis of all model parameters indicated that the receptor site density and the adsorption energy controlled the indium adsorption.

In this paper, the adsorption of phenol and 2-nitrophenol on a biopolymer-based biochar in single and binary systems was investigated at 298–328 K and pH 5. Experimental results indicated that the adsorption capacities of phenol were significantly reduced from single to binary systems compared to those obtained for 2-nitrophenol. This experimental evidence suggested an antagonistic effect between both adsorbates generating an inhibitive adsorption. In terms of modeling analysis, the single and binary adsorption isotherms were well reproduced by monolayer and competitive monolayer statistical physics models, respectively. These two models showed that phenol and 2-nitrophenol molecules have been mainly docked with an inclined and horizontal positions in single and binary systems, respectively. A detailed analysis of the number of captured phenol (n1) and 2-nitrophenol (n2) molecules per site in the binary systems demonstrated that its corresponding evolution varied with a completely inverse way thus corroborating the inhibition effect between phenol and 2-nitrophenol molecules. The monolayer and competitive monolayer models were used to estimate two adsorption energies to characterize the single and binary adsorption mechanisms. The analysis of the energetic parameters suggested that the adsorption process was a physisorption. The interpretation of all monolayer and competitive monolayer model parameters provided new insights that contributed to understand the single and binary adsorption mechanisms of phenol and 2-nitrophenol molecules on tested adsorbent.

Herein, a chitosan/polyamide nanofibers (CPN)-based adsorbent is employed to interpret the adsorption mechanism of two dyes, namely Reactive Black 5 (RB5) and Ponceau 4R (P4R), at different temperatures. Based on experimental results, the adsorption isotherms of RB5 and P4R dyes indicate that the separation process tends to a saturation plateau at high concentration, also suggesting that the dyes adsorption process occurs with the formation of a finite number of layers. To provide a reasonable explanation of the dyes adsorption mechanisms, three statistical physics models are used and discussed. The advanced modelling analysis reveals that the adsorption of both dyes occurs by the formation of two different adsorbed layers on CPN surface. Based on the application of the best statistical physics adsorption model, it was deduced that both dyes were anchored with horizontal and non-horizontal positions on CPN surface depending on temperature, which was concluded by investigation the captured number of dye molecules per CPN adsorbent site during the adsorption process. Based on these theoretical results, it was noted that the adsorption capacities at saturation followed this sequence: Q (P4R) > Q (RB5) for all investigated temperatures (i.e., 222.4, 261.3, 352.8, 482.2 mg/g for P4R and 198.6, 267.7, 288.2, 352.5 mg/g for RB5), indicating that CPN adsorbent was more effective for the P4R dye removal. The adsorption energies are studied to explain the difference in the interactions between dyes and adsorbent surface (P4R-CPN, RB5-CPN), and between these dyes (P4R-P4R, RB5-RB5), indicating that the removal of these adsorbates was based on a physisorption mechanism where a desorption process is possible. Comparing the estimated parameters of the best statistical physics model, it was concluded that both steric and energetic factors are mainly responsible for the adsorption of P4R and RB5 dyes on CPN.

This study reports the combination of new statistical physics models and density functional theory (DFT) for the analysis and understanding of the adsorption of heavy metals on a flamboyant biomass-based adsorbent. Single and ternary isotherms of the adsorption of Pb2+, Hg2+ and Zn2+ ions on an adsorbent obtained from the pyrolysis of flamboyant biomass were determined experimentally at pH 5 and 298–313 K. Experimental studies showed that the adsorption of Hg2+ on flamboyant char was higher than those of Zn2+ and Pb2+ in both single and ternary solutions. A strong antagonistic effect for the multicomponent adsorption of Zn2+ was identified due to the presence of other competitive metal ions in the ternary solution. The endothermic adsorption mechanism involved in both mono- and multi-metallic solutions was explained via the integration of the results from the adsorbent physicochemical characterization and calculations using statistical physics models and density functional theory. Theoretical studies showed that the single-compound adsorption of heavy metals correlated with the calculated DFT binding energies of oxygen-containing functionalities of flamboyant surface. On the other hand, the electronegativity and the thermodynamic stability of the metal – active site complexes determined the adsorbent selectivity and adsorption capacities in the simultaneous removal of these heavy metals. In particular, the carboxylic functional groups of flamboyant char were the main active sites involved in the adsorption of these heavy metals in both mono- and multi-component aqueous solutions. These new findings contribute to a deeper understanding of the mechanisms involved in the multicomponent adsorption of relevant water pollutants such as heavy metals using carbon-based adsorbents.

Statistical physics treatment has been used to study the adsorption of ethanol on two types of phenol resin-based adsorbents (KOH4-PR and KOH6-PR). In this work, we have used the adsorption isotherms of the two proposed systems (ethanol/KOH4-PR and ethanol/KOH6-PR) at different temperatures, in order to interpret the evolution of physicochemical parameters involved in the proposed model. For this reason, we have applied a multilayer model with saturation which is established through the grand canonical ensemble of statistical physics. This model has been selected from others by the determination coefficient R2 and applied to discuss the adsorption process. Five physicochemical parameters characterizing the adsorption process have been investigated namely the number of adsorbed ethanol molecules per site (n), the density of receptor sites (NM), the number of adsorbed layers (N2) and the energetic parameters (−ΔE1) and (−ΔE2). The equilibrium data were interpreted through these parameters in relation with their temperature dependence. Through this selection of the best fitting model and through fitted values of these parameters, we showed that the adsorption of ethanol molecules is not only a multilayer process but also a multimolecular process. The energetic parameters fitted values of the adsorption process showed that the adsorption process is exothermic and that the ethanol molecules are physisorbed on the phenol resin adsorbent. Van der Waals or the hydrogen interactions are implicated in the adsorption process. Thermodynamic potential functions such as the configurational entropy, Gibbs free energy and, internal energy are calculated. They indicate the macroscopic evolution of these potentials with pressure in relation with system temperature. The adsorption of ethanol onto phenol resin (KOH4-PR and KOH6-PR) is a spontaneous and globally exothermic in nature. Lastly, the adsorption isotherm of ethanol onto the types of phenol resin provides access to the pore sizes distribution (PSD), and also the adsorption energy distribution (AED).

In this paper, the advanced statistical physics models (ASPM) were used to provide reasonable interpretations of the adsorption of pharmaceuticals Ketoprofen (KTP) and Ibuprofen (IBP) on raw and ultrasound activated carbons. Monolayer and multilayer models were selected to explain the adsorption mechanisms of these pharmaceuticals. Based on the values of the captured pharmaceutical molecules (n), it was concluded that multi-molecular (n > 1) and multi-docking (n

A monolayer model extended to two energy levels (monolayer model 2) has been developed to fit the adsorption isotherms of acid blue 9 on Spirulina platensis (Sp LEB-52). These isotherms were obtain...