Reusable molecularly imprinted polymeric nanospheres for diclofenac removal from water samples

The preparation of efficient molecularly imprinted polymers materials (MIPs) for pharmaceutical residue removal is still a challenging task. Herein, we design uniformly molecularly imprinted polymer nanospheres via a precipitation polymerization method using methacrylic acid (MAA) as functional monomer andN,N-methylenebis(acrylamide) (MBAA) as a crosslinker for removal of diclofenac (DFC) as a model for pharmaceutical pollutants. Nanospheres with average size 200 nm were prepared with MAA:MBAA at a ratio of 1:7 and acetonitrile/toluene (1:1) as a porogenic solvent. The successful synthesis is evidenced by Fourier transform infrared spectroscopy, scanning electron microscopy, and with a particle size analyzer. The rebinding experiments confirmed that the more introduction of the carboxyl groups from MAA could remarkably improve the imprinting effect with a significantly increased imprinting factor and specific rebinding capacity reached 450 mg/g after 15 min. Furthermore, the adsorption capacity of the molecularly imprinted polymers is maintained above 85% after seven regeneration cycles, indicating that the molecularly imprinted polymers can be used multiple times. Moreover, the developed molecularly imprinted polymers show promising DFC removal efficiency from real water samples, which suggests that the prepared molecularly imprinted polymer nanospheres are promising in DFC separation.