Preparation of dual-dummy-template molecularly imprinted polymers coated magnetic graphene oxide for separation and enrichment of phthalate esters in water

A novel molecularly imprinted polymers (MIPs) was prepared by the sol-gel imprinting method on the surface of magnetic graphene oxide (MGO) modified with mesoporous silica (mSiO2), with dipropyl phthalate (DPRP) and diisononyl phthalate (DINP) as the dual-dummy templates. The prepared MIPs, which was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), etc., was subsequently employed for simultaneous separation and enrichment of six typical phthalates esters (PAEs) in water. Moreover, the adsorption performance of MIPs was evaluated by means of adsorption isotherms, kinetics and selectivity experiments. Results demonstrated that the adsorption process followed the pseudo-second-order kinetic model, with an equilibrium time of about 120 min and the equilibrium adsorption capacities of MIPs for PAEs ranging from 2.3 to 4.8 mg g−1 at 298 K. Besides, the prepared MIPs exhibited favorable selectivity and reusability for PAEs. Furthermore, an analytical method was proposed for determining trace PAEs in water samples by gas chromatography/mass spectrometry (GC/MS) combined with solid-phase extraction (SPE) using MIPs as the adsorbent. Factors that affected the extraction efficiency of PAEs were also examined and optimized. It was found that the limits of detection (LODs) and the limits of quantity (LOQs) for PAEs were 0.01–0.05 μg L−1 and 0.05–0.2 μg L−1, respectively. The spiked recoveries for PAEs were >92.9%, with the relative standard deviations (RSDs) of <3.8%. Consequently, the synthesized MIPs can serve as a promising material for the selective detection and removal of PAEs from water.