화학공학소재연구정보센터
Journal of Colloid and Interface Science, Vol.556, 529-540, 2019
Spray-drying water-based assembly of hierarchical and ordered mesoporous silica microparticles with enhanced pore accessibility for efficient bio-adsorption
The fast and scalable spray-drying-assisted evaporation-induced self-assembly (EISA) synthesis of hierarchically porous SBA-15-type silica microparticles from a water-based system is demonstrated. The SBA-15-type silica microparticles has bowl-like shapes, uniform micro-sizes (similar to 90 mu m), large ordered mesopores (similar to 9.5 nm), hierarchical meso-/macropores (20-100 nm) and open surfaces. In the synthesis, soft- and hard-templating approaches are combined in a single rapid drying process with a non-ionic tri-block copolymer (F127) and a water-insoluble polymer colloid (Eudragit RS, 120 nm) as the co-templates. The RS polymer colloid plays three important roles. First, the RS nanoparticles can be partially dissolved by in-situ generated ethanol to form RS polymer chains. The RS chains swell and modulate the hydrophilic-hydrophobic balance of F127 micelles to allow the formation of an ordered mesostructure with large mesopore sizes. Without RS, only worm-like mesostructure with much smaller mesopore sizes can be formed. Second, part of the RS nanoparticles plays a role in templating the hierarchical pores distributed throughout the microparticles. Third, part of the RS polymer forms surface "skins" and "bumps", which can be removed by calcination to enable a more open surface structure to overcome the low pore accessibility issue of spray-dried porous microparticles. The obtained materials have high surface areas (315-510 m(2) g(-1)) and large pore volumes (0.64-1.0 cm(3) g(-1)), which are dependent on RS concentration, HCl concentration, silica precursor hydrolysis time and drying temperature, The representative materials are promising for the adsorption of lysozyme. The adsorption occurs at a >three-fold faster rate, in a fivefold larger capacity (an increase from 20 to 100 mg g(-1)) and without pore blockage compared with the adsorption of lysozyme onto spray-dried microparticles of similar physicochemical properties obtained without the use of RS. (C) 2019 Elsevier Inc. All rights reserved.