Comprehensive Review of SBA-15 Mesoporous Silica: Functionalization Strategies, Diffusion Mechanisms, and Emerging Applications

Mesoporous materials have attracted increasing attention due to their ordered pore systems; tunable surface chemistry; and versatile applications in catalysis, adsorption, and environmental technologies. Among them, SBA-15 stands out for its large surface area, uniform mesopores, and high hydrothermal stability, which make it a promising platform for gas adsorption and mass transport studies. This review examines the functionalization of SBA-15 through strategies such as post-synthesis grafting and co-condensation, focusing on the introduction of amines, thiols, and organometallic species that enhance selectivity, adsorption capacity, and thermal stability. The discussion integrates classical diffusion models, including Fickian and Knudsen transport, with more advanced approaches such as the Maxwell–Stefan formalism, to describe molecular transport within mesoporous networks and highlight the role of van der Waals interactions in gas capture processes. Special emphasis is placed on the relationship between structural features and diffusive behavior, supported by recent advances in computational modeling and spectroscopic validation. Applications in CO2 capture, heterogeneous catalysis, drug delivery, and environmental remediation are critically assessed to illustrate the versatility of functionalized SBA-15. This review concludes by outlining future perspectives on the rational design of hierarchical and multifunctional mesoporous materials for clean energy conversion, pollutant removal, and biomedical applications.