Functionalization of SBA-15 mesoporous silica for highly efficient adsorption of glutathione: Characterization and modeling studies

Background: Pristine SBA-15 and amine or thiol-functionalized SBA-15 materials were synthesized, characterized, and highlighted by studying the glutathione (GSH) adsorption process in aqueous solutions. Methods: In this study, SBA-15 mesoporous materials were functionalized with 3-aminopropyltriethoxysilane (APTS) and (3-mercaptopropyl)triethoxysilane (MPTES) in order to introduce amine and thiol groups onto the surface by using a post-grafting method, respectively. For comparison, the SBA-15-based materials were used as adsorbents to further investigate the adsorption behaviour of GSH under various experimental conditions. Significant findings: To examine the underlying mechanism of the adsorption process, the kinetics of the GSH adsorption onto SBA-15-based adsorbents were fitted using pseudo-first order, pseudo-second order, Elovich, and Aharoni models. Adsorption isotherms showed that the Freundlich isotherm model was the most appropriate to simulate the adsorption of GSH molecules onto SBA-15-NH2 adsorbent and the Langmuir isotherm model for the two other substrates. In addition, the adsorption thermodynamics confirmed the exothermic behaviour of GSH adsorption process onto the SBA-15-SH adsorbent. In contrast, the capture of GSH molecules by the SBA-15-OH and SBA-15-NH2 adsorbents follows an endothermic reaction process. Finally, the adsorption nature of GSH onto SBA-15 adsorbents is classified as physisorption.