An effective method for the synthesis of yolk–shell magnetic mesoporous carbon-surface molecularly imprinted microspheres

This study aims to immobilise molecularly imprinted polymers (MIPs) on the surface of yolk–shell magnetic mesoporous carbon (Fe3O4@void@C) spheres for phthalate ester (PAE) recognition through an effective route. To link MIPs to Fe3O4@void@C spheres, carboxyl-modified yolk–shell magnetic mesoporous carbon (Fe3O4@void@C–COOH) was synthesised by first oxidising Fe3O4@void@C with H2O2, and MIPs were subsequently grafted on the surface of Fe3O4@void@C–COOH by a surface polymerisation method with diisononyl phthalate (DINP), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as template molecule, functional monomer and cross-linker, respectively. The structure and morphology of the synthesised materials were characterised by XRD, TEM, SEM, FT-IR, N2 sorption and magnetic susceptibility measurements. The synthesis conditions for the formation of Fe3O4@void@C–COOH were systematically investigated. It was observed that the chemical modification of Fe3O4@void@C is highly influenced by the type of oxidant, the concentration of H2O2, oxidation temperature and time. The adsorption isotherm and kinetics of Fe3O4@void@C-MIPs showed that Fe3O4@void@C-MIPs possessed good recognition, fast adsorption rates (approximately 20 min to reach equilibrium) and high adsorption capacities (569.2 mg g−1) toward PAEs, which were ascribed to their uniformity and monodispersity. In addition, Fe3O4@void@C-MIPs exhibited excellent reusability for the adsorption of PAEs over six adsorption–desorption cycles.