Sorption of diclofenac onto functionalized mesoporous silicas: Experimental and theoretical investigations

The aim of this paper was to evaluate the influence of surface chemistry on the structure and adsorption capacities of functionalized mesoporous SBA-15 organosilicas. The silica surface was decorated with a wide range of surface functional groups including amine, pyridine, urea, cyano, thiocyanate, thiol, and others. The synthesized materials were applied as sorbents of diclofenac, which is considered to be a priority hazardous pharmaceutical. For some of the samples there were observed very high adsorption uptakes reaching 925 mg per gram of the sorbent while for the others adsorption was negligible. The Density Functional Theory (DFT) calculations were made to investigate in detail interactions between diclofenac and the selected functional groups present on the silica surface. The calculations helped to establish links between the surface chemistry and the sorbent surface-diclofenac interactions responsible for adsorption properties.