Fabrication of dual-template molecularly imprinted mesoporous silica for simultaneous rapid and efficient detection of bisphenol A and diethylstilbestrol in environmental water samples

Abstract

Molecularly imprinted polymers (MIPs) are typically prepared using a single template molecule, which allows selective separation and enrichment of only one target analyte. They are not suitable for determination of complex real samples containing multiple analytes. In order to expand the practical application of MIPs, novel dual-template molecularly imprinted mesoporous silica (DMIMS) was prepared by a simple and facile hybrid dual-template imprinting strategy using bisphenol A (BPA) and diethylstilbestrol (DES) as templates for simultaneous selective recognition and extraction of the two endocrine disruptors in environmental water samples. The structure and morphology of the synthesized DMIMS were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis and N₂ sorption analysis. The results showed that DMIMS exhibited a spherical morphology, mesoporous structure and favorable thermal stability. More importantly, DMIMS was verified to exhibit fast kinetics, high rebinding capacity and excellent selectivity towards BPA and DES. DMIMS can reach equilibrium within 30 min and the saturated adsorption capacities of DMIMS for BPA and DES are 66.8 mg g⁻¹ and 43.9 mg g⁻¹, respectively. The selectivity coefficients of DMIMS are all far more than 1.0. Theoretical analysis showed that the experimental data fitted well to the pseudo-second-order model, indicating that chemical adsorption might be the rate-limiting step. Furthermore, the high adsorptive capability and selectivity of DMIMS were maintained almost constant after six runs. Finally, water samples were successfully analyzed with DMIMS and high recoveries (95.0–107.1%) and relative standard deviation (1.18–5.63%) were obtained. The limits of detection (3σ) of 3.4 × 10⁻⁴ mg L⁻¹ and 5.6 × 10⁻⁴ mg L⁻¹ were obtained for BPA and DES, respectively. Overall, these results demonstrated that DMIMS possesses great potential for simultaneous rapid and efficient detection of BPA and DES in environmental water samples.