Carbon dioxide (CO₂) is considered one of the most important greenhouse gases in the study of climate change. CO₂ adsorption was studied using the gas chromatography technique, while the Freundlich and Langmuir adsorption models were employed for processing isotherm data in the temperature range of 473–573 K. The isosteric heat of adsorption was calculated from the Clausius–Clapeyron equation. Moreover, the thermodynamic properties ΔG, ΔU, and ΔS were evaluated from the adsorption isotherms of Langmuir using the Van’t Hoff Equation. The four soil samples were recollected from San Juan Amecac, Puebla, Mexico, and their morphologies were investigated through X-ray diffraction (XRD) and N₂ adsorption at 77 K. The SJA4 soil has a crystalline Kaolinite phase, which is one of its non-metallic raw materials, and N₂ isotherms allowed for the determination of pore size distributions and specific surface areas of soil samples. The Barrett–Joyner–Halenda (BJH) distribution of pore diameters was bimodal with peaks at 1.04 and 3.7 nm, respectively. CO₂ adsorption showed that the SJA1 soil afforded a higher amount of adsorbed CO₂ in the temperature range from 453 to 573 K followed by SJA4 and finally SJA2, classifying this process as exothermic physisorption.

This text reports the morphological and textural behavior of the synthesis stages of a CMK-3 carbon type using a silicon matrix of the SBA-15 type calcined at 823 K as a template. During the synthesis, three intermediate materials were obtained because of (i) the addition of sucrose to the SBA-15 template (CCMK3-1st), (ii) the addition of sucrose to the CCMK3-1st material (CCMK3-2nd), and (iii) the carbonization by pyrolysis of the by-product CCMK3-2nd (CCMK3-F). The texture of the above materials was found by analyzing the N₂ adsorption isotherms, applying the classical adsorption theories to obtain the BET-specific surface and the meso- and micropore distributions by the BJH and Dubinin–Astakhov (DA) methods, respectively, in addition to the non-localized density functional theory (NLDFT). Similarly, with high resolution, the samples were analyzed morphologically by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Finally, the adsorption isotherms of CO₂ and CH₄ of the CMK-3 sample were obtained at six different temperatures in the interval of 243 to 303 K to evaluate the behavior of the isosteric enthalpy of adsorption (q_st) and its CO₂:CH₄ ideal selectivity. The final CMK-3 carbon presented two families of micro- and mesopores of 1.5 and 3.2 nm, nanopipe diameters of 3.5 nm, and a specific surface area of 1350 m²/g. It also presented values of 6.0 and 2.4 mmol/g adsorbed CO₂ and CH₄ at 243 K, respectively, and strong intermolecular interactions, with q_st values higher than 22 kJ/mol reflected in high selectivity values for an ideal mixture of CO₂:CH₄ (30:70%).

The nanoporosity in zeolite ZSM-5 was analyzed as a function of SiO2/Al2O3 molar ratio (MR). The internal pore structure was studied by high-resolution adsorption. Surface areas, microporous volume, characteristic energy of sorption, and pore-size distributions were calculated from N2 sorption isotherms by the BET, Langmuir, t-method of de Boer, αS-plot of Sing, direct comparative plots of Lee, Newnham, Dubinin-Astakhov, differential adsorption curves, and nonlocal density functional theory methods. The results indicated that MR dependence in these zeolites caused structural defects through micropore opening and widening as well as the emergence of further slit-like mesopores.

Our research group has developed a group of hybrid biomedical materials potentially useful in the healing of diabetic foot ulcerations. The organic part of this type of hybrid materials consists of nanometric deposits, proceeding from the Mexican medicinal plantTournefortia hirsutissimaL., while the inorganic part is composed of a zeolite mixture that includes LTA, ZSM-5, clinoptilolite, and montmorillonite (PZX) as well as a composite material, made of CaCO₃and montmorillonite (NABE). The organic part has been analyzed by GC-MS to detect the most abundant components present therein. In turn, the inorganic supports were characterized by XRD, SEM, and High Resolution Adsorption (HRADS) of N₂at 76 K. Through this latter methodology, the external surface area of the hybrid materials was evaluated; besides, the most representative textural properties of each substrate such as total pore volume, pore size distribution, and, in some cases, the volume of micropores were calculated. The formation and stabilization of nanodeposits on the inorganic segments of the hybrid supports led to a partial blockage of the microporosity of the LTA and ZSM5 zeolites; this same effect occurred with the NABE and PZX substrates.

Due to the nanoporous nature of zeolitic materials, they can be used as gas adsorbents. This paper describes the effect of critical admission temperature through narrow pores of natural ERI zeolites at low levels of coverage. This phenomenon occurs by adsorption of CH₄ and H₂ on pores in natural erionite. The zeolite was exchanged with aqueous solutions of Na⁺, Mg²⁺, and Ca²⁺ salts at different concentrations, times, and temperatures of treatment. Experimental data of CH₄ and H₂ adsorption were treated by the Langmuir equation. Complementarily, the degree of interaction of these gases with these zeolites was evaluated by the evolution of isosteric heats of adsorption. The Ca²⁺ and Mg²⁺ cations favor the adsorption phenomena of H₂ and CH₄. These cations occupy sites in strategic positions Ca1, Ca2, and Ca3, which are located in the nanocavities of erionite zeolites and K2 in the center of 8MR. Following the conditions of temperature and the exchange treatment, ERICa2 and ERINa3 samples showed the best behavior for CH₄ and H₂ adsorption.

Emissions of carbon dioxide (CO₂) and nitrogen dioxide (NO₂) in recent years has been increased considerably. One way to reduce the concentration of these greenhouse gases in the atmosphere is adsorptive capture. This paper describes the main results of adsorption of N₂, NO₂, and CO₂ on epistilbite, both natural and on samples that were chemically treated at various concentrations of HCl. Data on the adsorption of CO₂ and NO₂ were evaluated by the Freundlich and Langmuir equations. Additionally, the thermodynamic parameters of adsorption were calculated, including the degree of interaction of the zeolite samples with gases by gradually changing the isosteric heat capacities of adsorption. The acid treatment improves the adsorption capacity of epistilbite with respect to NO₂ and CO₂, due the replacement of large extra-framework cation by small H⁺ ions. The improvement in the distribution of pore sizes in epistilbite samples was calculated by the method of Barrett-Joyner-Halenda. The sample H1 that was prepared in a moderately concentrated acid showed the best behavior in the CO₂ adsorption processes, while the natural EPIN material preferably adsorbs NO₂.