Synthesis of mesoporous alumina with tunable structural properties

© 2015 Elsevier Inc. Mesoporous aluminas (MAs) with tunable structural properties including BET surface area, pore volume and pore size were successfully synthesized. The synthesis method was based on a sol-gel process via hydrolysis of aluminium isopropoxide associated with non-ionic block copolymer P123 as the structure-directing template in an acidic aqueous system. The MAs were characterized using thermogravimetry - differential thermal analysis (TG-DTA) for decomposition and mass loss characteristics during calcination, X-ray diffraction (XRD) for bulk crystallinity, transmission electron microscopy (TEM) for nano-scale morphology, selected area electron diffraction (SAED) for local crystallinity and N2 adsorption-desorption techniques for porous structural properties. By tailoring the amount of P123 and HNO3 addition, inorganic aluminium precursor Al(NO3)3 doping ratio and calcination temperature, MAs with controllable structural properties were obtained, leading to regular variations in the surface area (up to 409 m²g^-1), pore volume (0.4 cm³g^-1 ∼ 2.8 cm³g^-1) and pore size (5.0 nm ∼ 33.1 nm). Bovine serum albumin (BSA) was employed to evaluate the adsorption capability of the synthesized MAs. It was found that the structural properties of MA had a crucial effect on the BSA adsorption capability, increasing dramatically with increasing surface area, pore volume and pore size. For the sample MA4P15AlN (surface area 287 m²g^-1, pore volume 2.8 cm³g^-1 and pore size around 33.1 nm), the BSA adsorption amount reached 182.7 mgg^-1 in 2 h, higher than other MA samples as well as a silicon based reference sorbent material, SBA-15 (133.3 mgg^-1).