A versatile strategy to fabricate magnetic dummy molecularly imprinted mesoporous silica particles for specific magnetic separation of bisphenol A

Novel magnetic dummy molecularly imprinted mesoporous silica particles (m-DMIMSP) were prepared using a hybrid dummy imprinting approach combined with magnetic nanoparticles to obtain a magnetic material highly selective towards bisphenol A (BPA). The structure and morphology of synthesized m-DMIMSP were characterized by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometry, X-ray diffraction and N-2 sorption analysis. The results showed that m-DMIMSP exhibited a mesoporous structure and favorable magnetic properties with saturation magnetization of 4.87 emu g(-1). More importantly, m-DMIMSP displayed fast binding kinetics, high rebinding capacity of 76.8 mg g(-1), excellent imprint factor of 4.9 and extremely high selectivity towards BPA over 4,4-biphenol, diethylstilbestrol and hydroquinone, with selectivity coefficients all above 3.80. Moreover, the adsorptive capacity of m-DMIMSP was 2.0, 4.6 and 4.9 times higher than those of controlled magnetic molecularly imprinted mesoporous silica particles, magnetic dummy non-imprinted mesoporous silica particles and magnetic non-imprinted mesoporous silica particles, respectively, thus indicating the superiority of dummy molecular imprinting. Theoretical analysis showed that the experimental data fitted well to the pseudo-second-order model and Langmuir adsorption isotherm, indicating that chemical adsorption might be the rate-limiting step. Furthermore, the high adsorptive capacity and selectivity of m-DMIMSP remained almost constant after 8 runs. Finally, water samples were successfully analyzed with m-DMIMSP and high recoveries in the range of 95.6-106.2% were obtained. Overall, these results demonstrate that m-DMIMSP possesses great potentials for rapid and highly effective extraction of BPA from water samples.