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Novel ceramic foams were obtained by the replica method, using bentonite as alternative raw material and polyurethane sponge as template, where the latter also controls the distribution of the pore size of these ceramics. The synthesis of the ceramics was carried out using slurries of bentonite clay with different percentages of sodium carboxymethyl cellulose as a binder, and evaluating different calcination temperatures. The effect of these factors on the textural and morphological properties of the ceramic foams was studied. The porosity measured by mercury intrusion showed that the total porosity of the ceramic foams decreases as the calcination temperature increases. Furthermore, a small quantity of porosity is generated after the burnout of the binder during the calcination step. This porosity is given by pore sizes from 0.05 to 3 µm and it was increased with the amount of the binder that was increased, which was also confirmed by scanning electron micrographs. The characterization of bentonite clay, polyurethane, coated polyurethane sponge and ceramic foams was also complemented with thermogravimetric analysis, nitrogen adsorption at 77 K, and mechanical strength measurements. [ABSTRACT FROM AUTHOR]

The equilibrium adsorption and kinetics of CO 2 on several microporous materials has been studied at 273, 283 and 293 K and gas pressures of up to 100 kPa. The porous materials used in this work were two zeolites (5A and 13X), two metal–organic frameworks (Basolite A100 and Basolite Z1200), an activated carbon and two pillared clays (Al-PILC and Zr-PILC). The isothermal and non-isothermal diffusion models were applied to calculate the diffusion time constants ( D 0 / r c 2 ) from the uptake curves. The non-isothermal model was found to fit the experimental data well over the whole range of adsorption rates. The values found for the zeolites, which ranged from 0.020 to 0.043 s −1 , were lower than those for the metal–organic frameworks and pillared clays, which ranged from 0.036 to 0.081 s −1 , in the same interval of temperatures. Furthermore, the values of the diffusion time constants were found to depend on gas pressure. The pressure-dependence of the diffusion time constants was studied using the Darken equation. Finally, activation energy values were estimated from the temperature-dependence for all materials and it was found to increase in the order: Z1200 < Al-PILC < 13X < AC < Zr-PILC < 5A; A100. [ABSTRACT FROM AUTHOR]

In this study, we conducted experimental and Monte Carlo simulation studies in the grand canonical ensemble (GCMC) to investigate the role of molecular orientation and surface heterogeneity on the adsorption of N 2 at 77 K. Our research focused on a series of ordered nanoporous materials (SBA-15) with varying degrees of oxygen functionalities. Specifically, we examined the effects of surface heterogeneity on the calculation of pore size distribution (PSD) and the Brunauer-Emmett-Teller (BET) area of porous materials. To provide a comprehensive perspective, we compared our results with three levels of surface oxidation, including a pristine case without any surface oxidation. The results from both our experimental and simulation data reveal the importance of chemical heterogeneity in determining equilibrium properties such as molecular packing within the pores, differential enthalpies of adsorption, and N 2 orientation distribution. Our findings suggest that accurate characterization of surface heterogeneity is crucial for understanding gas adsorption in nanoporous materials and for developing better models for predicting their performance in various applications. Moreover, our simulations revealed substantial changes in the molecular orientation of adsorbate particles with increasing surface heterogeneity. This insight provides valuable information about the behavior of molecules within the nanoporous materials, further enhancing our understanding of the complex adsorption processes in these systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This research focuses on developing MIL-53-type compounds with Fe obtained with ligands derived from PET waste, followed by the controlled addition of hydrofluoric acid (HF). Incorporating HF into the MOF structure induced substantial changes in the material textural properties, resulting in a significant change in CO 2 adsorption. Furthermore, a distinctive structural alteration (breathing effect) was observed in the CO 2 isotherms at different temperatures; these structural changes have not been observed by X-ray diffraction (XRD) because this characterization has been performed at room temperature, whereas the adsorption experiments were conducted at 260, 273, and 303 K and different pressures. Subsequently, DFT studies were performed to investigate the CO 2 -filling mechanisms and elucidate the material respiration effect. This approach offers promising opportunities for sustainable materials with improved gas adsorption properties., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Herein, ordered mesoporous materials like SBA-15 and Al/SBA-15 were prepared using the pH adjustment method. Thus, these materials were developed in different pH of synthesis, from the pH adjustment method using a KCl/HCl solution and varying the Si/Al molar ratio (5, 25, and 75). All the ordered mesoporous materials were characterized by FRX, 27 Al NMR, SEM, XRD, N 2 adsorption/desorption, and CO 2 adsorption. From the applied method, it was possible to obtain SBA-15 and Al/SBA-15 with high mesoscopic ordering based on the XRD patterns, independent of the pH employed. From the chemical composition, the insertion of higher amounts of Al into the synthesis caused a progressive improvement in the structural and textural properties of the ordered mesoporous materials. Thus, the chosen synthesis conditions can lead to different aluminum coordination (tetrahedral and octahedral), which gives these materials a greater potential to be applied. The presence of Al in high amounts provides material with the ability to form micropores. Finally, the proposed method proved to be innovative; low-cost; less aggressive to the environment, with efficient insertion of aluminum in the framework of SBA-15 mesoporous material; and practical, based on only one step.

Mordenite is a well-known zeolite widely used for industrial processes. However, its pore architecture can be inconvenient due to diffusional issues. A study of the synthesis parameters from an organic-free dense gel was carried out to control the crystal morphology, which resulted in finned mordenite zeolite particles. The obtained materials were characterized by XRD, FTIR, 29 Si and 27 Al MAS-NMR, elemental analysis, nitrogen physisorption, SEM, and TEM. We found that careful manipulation of the hydrothermal parameters directly affected the sizes and morphologies of the crystallites and particles, as well as the textural properties of the final products. Additionally, it was found that mordenite could exhibit a fin morphology with additional mesoporosity, which is a promising means to reduce the diffusional problems of one-dimensional-channel zeolites.

The mixture containing alloy and oxide with iron-based phases has shown interesting properties compared to the isolated species and the synergy between the phases has shown positive effect on dye adsorption. This paper describes the synthesis of Fe 2 SiO 4 -Fe 7 Co 3 -based nanocomposite dispersed in Santa Barbara Amorphous (SBA)-15 and its application in dye adsorption followed by magnetic separation. Thus, it was studied the variation of reduction temperature and amount of hydrogen used in synthesis and the effect of these parameters on the physicochemical properties of the iron and cobalt based oxide/alloy mixture, as well as the methylene blue adsorption capacity. The XRD and Mössbauer results, along with the temperature-programmed reduction (TPR) profiles, confirmed the formation of Fe 2 SiO 4 -Fe 7 Co 3 -based nanocomposites. Low-angle XRD, N 2 isotherms, and TEM images show the formation of the SBA-15 based mesoporous support with a high surface area (640 m 2 /g). Adsorption tests confirmed that the material reduced at 700 °C using 2% of H 2 presented the highest adsorption capacity (49 mg/g). The nanocomposites can be easily separated from the dispersion by applying an external magnetic field. The interaction between the dye and the nanocomposite occurs mainly by π-π interactions and the mixture of the Fe 2 SiO 4 and Fe 7 Co 3 leads to a synergistic effect, which favor the adsorption.

The need for greener procedures is a fact to reduce residues, to decrease industrial costs, and to accomplish the environmental agreements. In an attempt to address this question, we propose the addition of a natural resource, Brazilian diatomite, to an MFI zeolite traditional synthesis. We have characterized the resulting product with different techniques, such as X-ray diffraction, microscopy, and gas sorption, and, afterwards, we evaluate the greenness of the process by the Green Star method. The results were promising: We obtained the desired topology in the form of small crystallites aggregated and a pore diameter of 0.8 nm. In conclusion, the product has the necessary characteristics for an adsorption or catalytic future tests and escalation to industrial production.

The chemistry between layered MWW zeolite and carbon black pearls (BP 2000) as an inexpensive hard template was investigated to develop a rational one-pot synthesis of MCM-22 microspheres. The characterization results showed that the insertion of BP 2000 in the gel synthesis did not substantially compromise the crystallinity and microporosity, and the microscopic analyses showed that BP 2000 played a key role in controlling the final morphology of the MCM-22 zeolite, creating beautiful dandelion-like microspherical particles. The morphology obtained is due to the tortuous shape of the hard template, the particular MWW particle crystals, the interaction with the external surface of the MWW zeolitic precursor, and the synthesis conditions. The stacking of MWW crystals with edge-to-face orientations generates meso-/macrovoids, allowing access to the interiors of the microspheres. The microspheres were homogeneous with sizes ranging from 6 to 8 μm with an increase of the external surface and a macroporous size distribution centered at 200 nm, which is two times that of the traditional MCM-22 zeolite., Competing Interests: The authors declare no competing financial interest.