Pyridine-, thiol- and amine-functionalized mesoporous silicas for adsorptive removal of pharmaceuticals

Pyridine-, thiol- and amine-functionalized mesoporous silica sorbents have been synthesized by co-condensation of tetraethoxysilane (TEOS) with the proper organosilica monomers. The resulting structural and morphological features were controlled not only by the arrangement of the polymeric template but also by the type of the functional group. Amine- and thiol-functionalized silicas were composed of aggregated nanopomus rings/tubes while pyridine-functionalized silica formed meso-cellular foam (MCF). Studies on adsorptive removal of pharmaceuticals showed that the fabricated amine- and pyridine-functionalized silicas adsorbed high amounts of pharmaceuticals within minutes. A gradual dissolution of loosely aggregated silica nanorings of aminated and thiolated silicas was observed, while the compact MCF structure of pyridine-functionalized sorbent was more resistant to water-driven degradation. As a result, the latter material could be reused without significant deterioration of its adsorption efficiency, which shows its usefulness for the removal of hazardous pollutants including pharmaceutical from waters and wastewaters.