Amine-modified SBA-15 and MCF mesoporous molecular sieves as promising sorbents for natural antioxidant. Modeling of caffeic acid adsorption

Abstract

This work presents a detailed study of caffeic acid adsorption on mesoporous SBA-15 and MCF silicas functionalized with (3-aminopropyl)triethoxysilane (APTES) and 3-[2-(aminoethylamino)propyl]trimethoxysilane (AEAPTMS). Synthesized mesoporous adsorbents were characterized using different analytical techniques such as N2 sorption, XRD, TEM, SEM and FT-IR. The adsorption studies of caffeic acid were conducted in various organic solvents. Moreover, the effect of water content in 2-propanol–water mixture on adsorption efficiency was investigated. The experimental data were best fitted to the Langmuir equation, followed by the Temkin, Dubinin–Radushkevich and Freundlich models. The maximum adsorption capacity values calculated from the Langmuir model demonstrated that SBA-15 and MCF silicas modified with AEAPTMS revealed better adsorption properties toward caffeic acid (192.3 and 161.3mg/g, respectively) as compared to the materials modified with APTES (125.0 and 113.6mg/g, respectively). The obtained results indicate that both SBA-15 and MCF silicas functionalized with AEAPTMS and APTES are promising materials for the entrapment of caffeic acid.