APTES functionalization in SBA-15: the effect on SO2 capture and detection applications.

The development of adsorbents for air pollutant remediation and effective monitoring is of interest. Then, the effect of the APTES functionalization ratio on the impact of the adsorption and detection of SO2 molecules was evaluated. The higher APTES functionalization material (SBA-15_6.1APTES) shows a high uptake of 1.15 mmol g-1 at 0.001 bar and 298 K. Fluorescence, time-resolved photoluminescence, and quantum yield experiments revealed a turn-on effect specifically for SO2 molecules, indicating high selectivity, suggesting host-to-guest energy transfer. Attractively, XPS measurement provided an understanding of the mechanism, suggesting hydrogen bonding and dipole-dipole interactions as the main interactions between SO2 molecules and SBA-15_6.1APTES. DFT calculations were performed to confirm these interactions. Furthermore, this study highlights the application of SBA-15 materials with different amino modifications for SO2 treatment and provides insight into the interaction mechanism using experimental techniques.

Influence of Pressure and Temperature on the Flexible Behavior of Iron-Based MIL-53 with the CO2 Host: A Comprehensive Experimental and DFT Study.

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 CO2 adsorption. Furthermore, a distinctive structural alteration (breathing effect) was observed in the CO2 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 CO2-filling mechanisms and elucidate the material respiration effect. This approach offers promising opportunities for sustainable materials with improved gas adsorption properties.

Development of ceramic honeycomb monolith from natural zeolite tested as adsorbent to remove methylene blue in aqueous media.

This work presents a ceramic monolith with a honeycomb structure obtained from a natural zeolite (clinoptilolite), bentonite, and alumina. The monolith obtained by extrusion had a cell density of 57 CPSI (cells per square inch), an open frontal area of 52% w/w, and a wall thickness of 0.9 mm. The raw materials and the natural zeolite ceramic monolith (NZCM) were characterized by X-ray diffraction, N2 adsorption-desorption at 77 K, CO2 adsorption at 273 K, mercury intrusion-extrusion, axial compression tests, resistance to leaching at acidic and basic pH, and point of zero charge. The NZCM presented an SBET = 31 m2∙g-1, a modal micropore size of 0.44 nm, a porosity of 39%, the compressive stress = 14 MPa, and a pHPZC = 7.5. The NZCM was used as an inexpensive and easy-to-handle adsorbent to remove methylene blue (MB) dye in batch studies of kinetics and adsorption isotherms. From modeling of adsorption kinetic data, the predominant phenomenon in this system was physisorption. The modeling of adsorption isotherm data shows that the material has homogeneous active sites. The adsorption occurs by monolayer formation, finding a maximum capacity removal rate of 27 mg MB per gram of NZCM. Compared to other structured materials, a high capacity for removing MB with the ceramic monolith was obtained along with good mechanical properties and resistance in acidic and alkaline environments.