Zirconium involved platelet SBA-15: Synthesis and application to tannic acid adsorption

Mesoporous silica materials are designed to accommodate reactants of large molecular sizes in various applications. The tubular or platelet Santa Barbara amorphous-15 and SBA-15 were synthesized in this study at 90 °C or 120 °C with zirconyl oxychloride or zirconium chloride added for regulating the pore geometry. The tubular SBA-15 has monodispersed pores of length 800 nm and diameter of 5.7‒7.5 nm, yielding a surface area of 685‒737 m²/g. The platelet SBA-15 has monodispersed pores of length 200 nm and diameter of 6.4‒6.8 nm, producing surface area of 435‒752 m²/g. Amine modification reduces the pore diameter and surface area. The loadings of amine on 24 h amine-modified tubular SBA-15 ranged 116.7‒121.0 mg/g, while those on platelet SBA-15 ranged 93.7‒148 mg/g. The zirconium chloride induced platelet SBA-15 has higher amine loading than the zirconyl oxychloride induced ones. Based on kinetic data of amine modification, the effective diffusivity of (3-aminopropyl)triethoxysilane in toluene in platelet SBA-15 is estimated 4.8 times to the tubular counterparts. The so-synthesized platelet SBA-15 can favorably adsorb tannic acid at maximum capacity of 769 mg/g.