Adsorption Of Ethanol Molecules Research Articles

Assignment of IR spectra of ethanol at Brønsted sites of H-ZSM-5 to monomer adsorption using a Fermi resonance model.

Understanding how alcohol molecules interact with the Brønsted acid sites (BAS) of zeolites is a prerequisite to the design of zeolite catalysts and catalytic processes. Here, we report IR spectra for the adsorption of ethanol on a highly crystalline sample of H-ZSM-5 zeolites exposed to ethanol gas at increasing pressure. We use density functional theory in combination with a FERMI resonance model to assign the measured spectra to a single adsorbed ethanol molecule per BAS. Specifically, we assign the bands at 2450 cm-1 and 1670 cm-1 to a FERMI resonance between the fundamental (Z)O-H stretching band of a single-ethanol-loaded BAS and the first overtone of the (Z)O-H out-of-plane bending. We conclude that adsorbed dimers do not contribute in a noticeable way up to a concentration of almost one ethanol molecule per BAS site. We further show that hybrid functionals (B3LYP) are required to get a close match between the predicted and experimental spectra, whereas commonly used generalized gradient type functionals such as PBE incorrectly describe the potential energy surface. They overestimate the redshift of the OH stretching band on hydrogen bond formation which results in an erroneous assignment of the IR bands.

Assessment of machine learning models trained by molecular dynamics simulations results for inferring ethanol adsorption on an aluminium surface

Molecular dynamics (MD) simulations can reduce our need for experimental tests and provide detailed insight into the chemical reactions and binding kinetics. There are two challenges while dealing with MD simulations: one is the time and length scale limitations, and the latter is efficiently processing the massive amount of data resulting from the MD simulations and generating the proper reaction rates. In this work, we evaluated the use of regression machine learning (ML) methods to solve these two challenges by developing a framework for ethanol adsorption on an Aluminium (Al) slab. This framework comprises three main stages: first, an all-atom molecular dynamics model; second, ML regression models; and third, validation and testing. In stage one, the adsorption of ethanol molecules on the Al surface for various temperatures, velocities and concentrations is simulated using the large-scale atomic/molecular massively parallel simulator (LAMMPS) and ReaxFF. The outcome of stage one is utilised for training, testing, and validating the predictive models in stages two and three. We developed and evaluated 28 different ML models for predicting the number of adsorbed molecules over time, including linear regression, support vector machine (SVM), decision trees, ensemble, Gaussian process regression (GPR), neural network (NN) and Bayesian hyper-parameter optimisation models. Based on the results, the Bayesian-based GPR showed the highest accuracy and the lowest training time. The developed model can predict the number of adsorbed molecules for new cases within seconds, while MD simulations take a few weeks. This adsorption rate can then be used in macroscale simulations to tackle the time and length scale limitations. The proposed numerical framework has the potential to be generalised and, therefore, contribute to future low-cost binding reaction estimations, providing a valuable tool for industry and experimentalists.

Exploring the Gas-Sensing Mechanism of a WO3 Nanowires-Based Sensor for Ethanol Detection by Near-Ambient Pressure XPS

The WO3 nanowires (NWs), fabricated on a commercial Al2O3-based sensor platform, underwent near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) analysis during ethanol detection. Our findings revealed challenges that may appear in utilizing NAP-XPS studies for studying a real gas sensor in operando conditions. Through NAP-XPS analysis, we explored the gas-sensing mechanisms of pristine and Pt-decorated WO3 NWs for ethanol sensing at different temperatures, demonstrating a combination of several mechanisms commonly observed in metal-oxide chemiresistors. For ethanol sensing, the primary driving force for the sensor's macroscopic electrical response at low temperatures was the adsorption of ethanol molecules. Conversely, at high temperatures, it involved the adsorption of ethoxy groups along with the reducing effect of ethanol on the WO3 surface. It is shown that the surface oxygen vacancies play a crucial role in the ethanol sensing mechanism of WO3 NWs-based gas sensors. Figure 1

NAP-XPS study of surface chemistry of CO and ethanol sensing with WO3 nanowires-based gas sensor

The nanowires prepared on a commercial Al2O3-based sensor platform were studied by near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) upon detecting CO and ethanol. Our findings indicated that the ex-situ prepared WO3 NWs-based gas sensor might not be suitable for NAP-XPS studies, as the surfaces tend to accumulate significant carbon contamination, which remains on the surface even after long-term annealing in mbar range oxygen atmosphere at 593 K. To address this challenge, we developed a methodology involving exposure of the sensor to NOx, which effectively cleans the surface and enables the detection of subtle chemical changes upon exposure to various carbon-containing analytes. Using NAP-XPS analysis, we investigated the gas sensing mechanisms of WO3 NWs for CO and ethanol at different temperatures, revealing that it might combine several mechanisms commonly observed in metal-oxide chemiresistors. It is shown that the response to CO rather arises from the quick interaction of CO molecules with the ionosorbed oxygen. In the case of ethanol sensing, the main driving force for the sensor macroscopic electrical response at low temperatures is the adsorption of ethanol molecules. In contrast, at high temperatures, it combines the adsorption of ethoxy groups with the strong reducing effect of EtOH on the WO3 surface.

Selective detection of ethanol at low concentration by ZnO@ZIF-8 porous nanosheets

Effectively improve the sensitivity of semiconductor gas sensors, reduce the working temperature and improve its detection ability at low concentrations are priority for practical applications. However, the design of appropriate sensing materials has become a great challenge. Herein, two-dimensional (2D) ZnO@ZIF-8 porous nanosheets (PNSs) heterostructures are prepared via a facile solvothermal method for ethanol detection. ZIF-8 can be used as a “breathable” support/filter layer to reduce self-accumulation of ZnO PNSs. ZnO@ZIF-8–24 exhibits an enhanced response (Ra/Rg=58) with high selectivity (SEthanol/SInterfering values ranged from 2.1 to 25.2) toward 50 ppm ethanol at 240 °C compared to ZnO. Meanwhile, ZnO@ZIF-8 (Ra/Rg=7.2) has better response than ZnO (Ra/Rg=2.8) at low concentration (5 ppm).The enhancement is ascribed to the increased exposure of active sites due to the inhibition of self-stacking of two-dimensional porous nanosheets by ZIF-8 nanoparticles. Furthermore, the heterostructures can strengthen the electron transfer and adsorption of ethanol molecules on ZIF-8. Thus, our research provides a new approach for the application of 2D heterostructures in gas sensing.

Carbon molecular sieve-functionalized graphene sensors for highly sensitive detection of ethanol

The surface functionalisation of graphene enables its application for the facile detection of low-concentration volatile organic compounds. Herein, we demonstrated that the carbon molecular sieve (CMS) functionalisation of graphene nanoribbons (GNRs) prepared using chemical vapour deposition (CVD) enhances their ethanol gas sensing performance by three orders of magnitude. The presence of the CMS layer on the GNRs was confirmed using helium ion microscopy and Raman spectroscopy. The porosity of the CMS functionalization of GNRs was confirmed using transmission electron microscopy. Unlike the CVD GNR field-effect transistor (FET), the CMS-functionalised GNR FET (CMSF-GFET) showed a sensitivity of 50 ppb, and the sensing performance improved with an increase in temperature. The high sensitivity of the CMSF-GFET can be attributed to the catalytic activity of the CMSs and the dipole interaction between the adsorbed ethanol molecules, which led to enhanced graphene-ethanol charge transfer and van der Waals interaction. The dependence of this charge transfer on the applied tuning voltage was investigated using the charge neutrality point disparity (CNPD) method. It was found that the CNPD value increased with an increase in the ethanol gas concentration, confirming that the CMS functionalisation induced the dipole interaction between the adsorbed ethanol molecules and the GNR surface.

Experimental and density functional theory computational studies on highly sensitive ethanol gas sensor based on Au-decorated ZnO nanoparticles

In this paper, a highly sensitive gas sensor based on zinc oxide nanoparticles decorated by gold nanoparticles is introduced. To achieve this purpose, the hydrothermal method was utilized to synthesize ZnO, which led to a highly porous surface with nanoparticles size less than 100 nm. Various effective parameters on the performance of a gas sensor, including the optimum annealing temperature from 500 °C to 800 °C and decorating different quantities of Au nanoparticle (0.5, 2, 4, and 7 wt%) on the ZnO surface were investigated. Results demonstrated that in the optimum annealing temperature (500 °C), 4 wt% Au-decorated ZnO sensor shows about five times better response than that of a ZnO sensor and improved response time from 36 seconds down to 3 seconds. Besides, repeatability, selectivity, and linearity of the responses were examined for increasing the reliability of the sensor. Also, experimental findings are supported by the theoretical calculations, using Density Functional Theory method. Results revealed that Au atoms on the surface lead to dehydrogenation of ethanol molecules, while this is not the case for the pure ZnO surface. Also, ethanol molecules adsorption on the Au decorated ZnO surface have optimum Au concentration, which is confirmed by theoretical and experimental results. Mulliken population and projected density of state analyses indicate that after adsorption of ethanol molecules on the surface, electrons migrate from ethanol toward the surface. As a consequence, the resistance of the slab decreases.

Ultrasonically modified P25-TiO2 /In2O3 heterostructured nanoparticles: An efficient dual- responsive photocatalyst for solution and gas phase reactions

BackgroundDesigning and fabricating an efficient heterostructured photocatalyst for degrading organic pollutants is a major concern for environmental remediation researchers. In that series we fabricated a P25-TiO2/In2O3 (PT/In) heterostructured nanocomposite via the facile ultrasonication and sol-gel synthesis method. MethodsIn both solution and gas-phase methods, the photocatalytic efficiency of the obtained PT/In nanocomposite was investigated. DRIFT-IR was measured at room temperature with the effect of adsorbed ethanol molecules, which would be used as a different approach to confirm the photocatalytic reaction mechanism. Significant FindingsUnder UV-Visible light illumination, the PT/In-4 nanocomposite was found to be an excellent photocatalyst for degrading Acid Blue (AB) dye. The calculated degradation rate constant (k) of PT/In-4 was 4.0 × 10−2 min−1, which was 13.3 and 5.7 times higher than that of PT-4 (0.3 × 10−2 min−1) and bare In2O3 (0.7 × 10−2 min−1) materials, respectively. The enhancement in photocatalytic performance is owing to the synergistic effect of the heterojunction between TiO2 and In2O3 and a reduction in the recombination rate. Furthermore, the PT/In-4 nanocomposite showed high stability even after five consecutive cycles. The photocatalytic mechanism was proposed based on experimental results obtained through the gas phase photocatalytic studies via DRIFT-IR technique.

Nanoporous Activated Carbon Functionalized Graphene Sensors for Selective Detection of Ethanol

Graphene surface functionalization enables the facile detection of low concentration volatile organic compounds (VOCs). Herein, activated carbon functionalization of chemical vapour deposition (CVD) graphene is shown to enhance ethanol gas sensing in CVD graphene by three orders of magnitude. The presence of activated carbon was confirmed via Helium Ion Microscopy, and Raman spectroscopy and porosity were confirmed via Transmission Electron Microscopy (TEM). Unlike CVD graphene, the activated carbon functionalized graphene field effect transistor (aCF-GFET) had a sensitivity of 50 ppb with performance improving with increase in temperature. The extreme activated carbon-induced sensitivity is attributed to the catalytic activity and oxidation of the adsorbed ethanol molecules, consequently inducing higher graphene-ethanol charge transfer and Van der Waals bonding. The dependence of this charge transfer on the applied tuning voltage was investigated using the charge neutrality point disparity (CNPD) method, which shows an increase in CNPD values with increasing concentration, confirming the activated carbon-induced oxidation of adsorbed ethanol molecules.

Dependence on co-adsorbed water in the reforming reaction of ethanol on a Rh(111) surface.

We have studied the reforming reaction of ethanol co-adsorbed with atomic oxygen (O*, * denotes adspecies) and deuterated water (D2O*) on a Rh(111) surface, with varied surface probe techniques under UHV conditions and with density-functional-theory calculations. Adsorbed ethanol molecules were found to penetrate readily through pre-adsorbed water, even up to eight overlayers, to react at the Rh surface; they decomposed at a probability promoted by the water overlayers. The production probabilities of H2, CO, CH2CH2 and CH4 continued to increase with co-adsorbed D2O*, up to two D2O overlayers, despite separate increasing rates; above two D2O overlayers, those of H2, CO and CH2CH2 were approximately saturated while that of CH4 decreased. The increased (or saturated) production probabilities are rationalized with an increased (saturated) concentration of surface hydroxyl (OD*, formed by O* abstracting D from D2O*), whose intermolecular hydrogen bonding with adsorbed ethanol facilitates proton transfer from ethanol to OD* and thus enhances the reaction probability. The decreasing behavior of CH4 could also involve the competition for H* with the formation of H2 and HDO.

Molecular description of the coil-to-globule transition of Poly(N-isopropylacrylamide) in water/ethanol mixture at low alcohol concentration

Poly (N-isopropylacrylamide), PNIPAM, is a widely studied polymer, which serves as a key constituent of nanostructured soft materials with responsive properties. Upon increasing temperature the PNIPAM polymer chain undergoes a reversible coil-to-globule transition at T~305 K, which is reflected by a volume phase transition in cross-linked architectures, such as microgels, valuable for many practical applications. The addition of a cosolvent is a simple method to tune the transition temperature according to the specific purpose. In this study, we use atomistic molecular dynamics simulations to explore the solution behavior of a PNIPAM chain in a mixture of water and ethanol, acting as cosolvent, at low alcohol concentration. Our simulations reproduce the occurrence of the coil-to-globule transition of the polymer chain at 289 K, a temperature lower than that measured in water, in full agreement with experimental findings. By monitoring the temperature evolution of structural and dynamical properties of the PNIPAM-water-ethanol ternary system, we detect a localization of ethanol molecules at the polymer interface, mainly due to interactions between isopropyl and ethyl groups. We observe that the transition occurs without a release of adsorbed ethanol molecules, but with a loss of water molecules from the surrounding of PNIPAM hydrophobic moieties that favours the aggregation of ethanol molecules close to the polymer. Our results support the idea that both the decreased chemical potential of water in the bulk of the mixture and the competition between water and ethanol molecules in the interactions with the polymer play a driving role in the transition.

MoO3 nanoflakes coupled reduced graphene oxide with enhanced ethanol sensing performance and mechanism

In this paper, MoO3 nanoflakes coupled reduced graphene oxide (MoO3-rGO) composites were fabricated by annealing the MoS2-GO nanosheet, and the MoO3-rGO shows high sensitivity, fast response, and good selectivity to ethanol. The response towards 100, 200, 500, and 8000 ppm of ethanol is 53, 68.98, 117.0, and 702, respectively, which are 5.4, 4.83, 5.05, and 3.64 times higher than the MoO3 at the working temperature of 310 ºC. Besides, the response time of MoO3-rGO to 100 ppm of ethanol at 280, 310, and 350 ºC is 7 s, 6 s, and 4 s, respectively. In addition, the MoO3-rGO shows good selectivity to ethanol over n-propanol, methanol, isopropanol, xylene, acetone, and benzene. ESR and XPS spectra of samples before and after exposed in ethanol have been used to detect the vacancy oxygen and chemical state of the MoO3 in the responding process, and the possible sensing mechanism of the MoO3 to ethanol has also been discussed. Both the adsorbed oxygen and lattice oxygen participate in the reaction process, and the adsorbed ethanol molecules is catalytically oxidized into H2O and CO2 molecules, and in this process the resistance has changed. And the results indicate that the Mo5+ also plays an important role in the sensing process.

Statistical physics modeling of ethanol adsorption onto the phenol resin based adsorbents: Stereographic, energetic and thermodynamic investigations

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).

Adsorption of ethanol molecules on the Al (1 1 1) surface: a molecular dynamic study.

The adsorption process of ethanol molecules on Al slabs was investigated by molecular dynamic simulations with a ReaxFF force field. The force field used in this paper has been validated by comparing adsorption energy results with quantum mechanical (QM) calculations. All simulations were performed under the canonical (NVT) ensemble. The single-molecule adsorption simulation shows that the hydroxyl group plays a more important role in the whole progress than the ethyl group. Besides, decomposition of hydroxyl groups was also observed during multimolecule adsorption processes. Simulations of adsorption processes of Al slab by ethanol molecules at different temperatures and pressures (controlled by the number of ethanol molecules) was also performed. System energy and radial distribution function (RDF) plots were invoked to describe adsorption processes and centro-symmetry parameter (CSP) analysis was adopted to study the surface properties with coating layers. Our results indicate that the whole adsorption process can be divided into two periods and the greater the pressure, the more ethanol molecules diffuse into the Al slab. How raising the temperature helps the adsorption processes is related to the initial number of molecules. The crystal structure of the Al surface will become amorphous under the constant impact of ethanol molecules.

Localized Surface Plasmon Resonance of Reduced Graphene Oxide/Ag Hybrid for Gas Sensing Application

Localized surface plasmon resonance of metallic nanoparticles has been widely employed for gas sensing applications. Since the response of bare nanoparticles is usually weak, it is possible to improve their responses by utilizing the high gas adsorption capability of 2-D materials. In this paper, we developed an optical gas sensor by decorating reduced graphene oxide (rGO) sheets with Ag nanoparticles for the detection of ethanol vapor at the room temperature. We showed that the gas sensitivity of bare Ag nanoparticles can be enhanced by utilizing rGO sheets. We observed improved responses for structures in which rGO was fabricated above the nanoparticles (rGOup/Ag) compared with the structures with rGO below the nanoparticles (Ag/rGOdown). Gas sensitivity was improved 1.47 and 2.75 times, respectively, in the Ag/rGOdown and rGOup/Ag structures compared with the bare Ag nanoparticles. Our results demonstrate that the adsorption of ethanol molecules on the Ag nanoparticles/rGO hybrids leads to not only a plasmonic shift occurring in bare Ag nanoparticles but also an intensity change in the extinction spectrum. In other words, alteration of rGO conductivity due to the gas adsorption leads to an intensity variation in optical spectrum, which can be utilized for improving gas sensing. Finally, we performed a finite-element analysis by assuming the electron exchange between Ag nanoparticles/rGO hybrids and target gas through redox reactions to assess the validity of observed experimental results. Our numerical results confirmed the observed experimental results.

Molecular dynamics simulations of aluminum nanoparticles adsorbed by ethanol molecules using the ReaxFF reactive force field

The adsorption of ethanol molecules on annealed aluminum nanoparticles was investigated by ReaxFF molecular dynamics simulations. The force field used in this paper has been validated by comparing the obtained adsorption process results with the results of quantum mechanical (QM) calculations. First, the case of single molecule adsorption was investigated and was shown to be a kind of chemisorption. We also simulated the processes of coating the aluminum nanoparticles with ethanol molecules at different temperatures and pressures. The results indicate that two zones were formed around the surface of aluminum nanoparticles by different interactions during the adsorption processes. The radial distribution function plots and isothermal adsorption curves were used to describe the behaviors. The results show that hydrogen-bonding formed by the ethanol molecules in the solution is a constituent of the coating layer and that the adsorption rate is proportional to the pressure. The cycle-coating method is adopted to produce a fully coated particle, and the oxidation resistance test shows that at 300 K, the organic layer can adsorb the oxygen atom rather than decompose by oxidation. Our simulation results are in good agreement with the results of experimental observations.

Effect of ethanol on the crystallization and phase transformation of MgCO3·3H2O in a MgCl2–CO2–NH3·H2O system

The effect of ethanol on the crystallization and phase transformation of MgCO3·3H2O in a MgCl2–CO2–NH3·H2O system was investigated at 40 °C. The obtained crystals were characterized by X-ray diffraction and scanning electron microscopy, and the phase transformation behaviors of the MgCO3·3H2O crystals were studied quantitatively using an established thermal analysis method. The results showed that ethanol played a key role in inhibiting the aggregation of MgCO3·3H2O crystals because the adsorption of ethanol molecules on nuclei surfaces was preferential to that of water molecules. Active Mg2+ ions could be separated from the nuclei surfaces when <30% ethanol was added, preventing secondary nucleation during the crystallization of MgCO3·3H2O. As a result, highly dispersed and stable MgCO3·3H2O rod crystals with smooth surfaces and uniform sizes (length of 25–30 μm and diameter of 2–3 μm) were successfully prepared with 30% ethanol at 40 °C. However, the rod-like MgCO3·3H2O crystals started to dissolve with >40% ethanol in solution, leading to the formation of more stable, flower-like crystals of 4MgCO3·Mg(OH)2·4H2O. The results of this study could contribute to the development of methods for controllable crystallization of MgCO3·3H2O.

Influence of an Al2O3 surface coating on the response of polymeric waveguide sensors.

The responses of a polymer ridge waveguide Young interferometer with and without a bilayer of Al2O3/TiO2, fabricated by atomic layer deposition, are studied and compared when applied as an aqueous chemical sensor. The phase shift of the guided mode, as a result of the change in refractive index of the cover medium, is monitored. The results indicate that the over-coating affects the linearity of the sensor response. The effect of concentration on the linearity of the sensor response is investigated by applying different concentrations of water-ethanol solution. Although the performance of the sensor is improved by the additional layers, the study reveals a non-monotonic behavior of the device. We show that it comes mainly from the adsorption of ethanol molecules on the surface of the films. Such an understanding of the platform is crucial for sensing of analytes involving polar molecules.

The effect of Cu[sbnd]Mg[sbnd]Fe layered double hydroxide on the electrocatalytic activity of gold nanoparticles towards ethanol electrooxidation

In this work, a CuMgFe layered double hydroxide-gold nanoparticles composite on a glassy carbon electrode (LDH/AuNPs/GCE) was used as a novel electrocatalyst for ethanol oxidation in alkaline media. The LDH/AuNPs/GCE was fabricated by electrodeposition of AuNPs on a GCE, and followed by the deposition of the CuMgFe LDH synthesized using a hydrothermal method. The surface morphology of the prepared electrode was characterized using field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX), demonstrating the successful formation of the proposed catalyst. FE-SEM images showed that the electrodeposited AuNPs in the size of 50–100 nm are covered uniformly by the CuMgFe LDH film consisting of fine nanoparticles and macropores. This morphology of the LDH increased the real surface area of the catalyst. In the next step, the catalytic performance of the LDH/AuNPs/GCE towards ethanol was compared with the AuNPs/GCE and AuNPs/LDH/GCE. The results showed the catalytic performance of the LDH/AuNPs/GCE is higher than the other electrodes. It was found that the adsorption of ethanol molecules on the CuMgFe LDH, that increases their concentration around the active sites of AuNPs, plays a significant role in the enhancement of the catalytic activity of the LDH/AuNPs/GCE. Moreover, cyclic voltammetry and chronoamperomety tests indicated that CuMgFe LDH results in an increase in the long-term stability of the LDH/AuNPs catalyst against the poisoning species, as compared with the AuNPs catalyst. Therefore, the CuMgFe LDH/AuNPs composite is proposed as an efficient anodic electrode for use in direct ethanol fuel cells in alkaline media.

Physicochemical parameters interpretation for adsorption equilibrium of ethanol on metal organic framework: Application of the multilayer model with saturation

This work is a theoretical investigation of the ethanol adsorption on metal organic framework. The main objective of this work is to explain the adsorption isotherms at different temperatures in order to relate this process by physicochemical parameters. A proposed statistical physics model called ‘multilayer model with saturation’ was selected and applied to interpret the adsorption data. Five physicochemical parameters in relation with the adsorption process were included, such as the number of ethanol molecules per site (n), the receptor site density (NM), the number of adsorbed layers (N2) and the adsorption energies (−ΔE1) and (−ΔE2). The equilibrium data were interpreted through these parameters. Simulation results showed that the adsorption of ethanol molecules is multi-molecular process. The study of the total saturation adsorbed quantity indicates that the adsorption process is exothermic. The magnitudes of the calculated adsorption energy indicate that the ethanol molecules are physisorbed on metal organic framework. Van der Waals interactions are implicated in the adsorption process.