Amine-Functionalized Natural Rubber/Mesostructured Silica Nanocomposites for Adsorptive Removal of Clofibric Acid in Aqueous Phase

This study is the first report on the synthesis, characterization and application of amine-functionalized mesoporous nanocomposites based on natural rubber (NR) and wormhole-like mesostructured silica (WMS). In comparison with amine-functionalized WMS (WMS-NH(2)), a series of NR/WMS-NH(2) composites were synthesized via an in situ sol-gel method in which the organo-amine group was grafted onto the nanocomposite surface via co-condensation with 3-aminopropyltrimethoxysilane (APS) as the amine-functional group precursor. The NR/WMS-NH(2) materials had a high specific surface area (115–492 m(2) g(−1)) and total pore volume (0.14–1.34 cm(3) g(−1)) with uniform wormhole-like mesoporous frameworks. The amine concentration of NR/WMS-NH(2) (0.43–1.84 mmol g(−1)) was increased with an increase in the APS concentration, corresponding to high levels of functionalization with the amine groups of 53–84%. The H(2)O adsorption–desorption measurement revealed that NR/WMS-NH(2) possessed higher hydrophobicity than WMS-NH(2). The removal of clofibric acid (CFA), a xenobiotic metabolite of the lipid-lowering drug clofibrate, from the aqueous solution using WMS-NH(2) and NR/WMS-NH(2) materials was investigated using a batch adsorption experiment. The adsorption was a chemical process in which the pseudo-second order kinetic model expressed the sorption kinetic data better than the pseudo first-order and Ritchie-second kinetic order model. In addition, the CFA adsorption sorption equilibrium data of the NR/WMS-NH(2) materials were fitted to the Langmuir isotherm model. The NR/WMS-NH(2) with 5% amine loading had the highest CFA adsorption capacity (6.29 mg g(−1)).