Magnetic molecularly imprinted microspheres via yeast stabilized Pickering emulsion polymerization for selective recognition of λ-cyhalothrin

In our study, magnetic molecularly imprinted microspheres (MMIMs) were prepared via Pickering emulsion polymerization. The template λ-cyhalothrin (LC), functional monomers and hydrophobic Fe3O4 nanoparticles, served as magnetic carrier, were contained in oil phase. Modified yeast dispersed in water phase was employed as stabilizer to establish stable oil-in-water Pickering emulsion, and the imprinting process was conducted by thermally initiated radical polymerization of functional and cross-linked monomers. Characterization results indicated that the Pickering emulsion and MMIMs were successfully produced. The MMIMs possessed thermal stability (below 200 °C), magnetic sensitivity (Ms = 0.73 emu g−1) and magnetic stability (over the pH range of 2.0–8.0). Then, the MMIMs were used as sorbents for the selective recognition of LC. The Langmuir isotherm model gave a better fit to the experimental data, indicating the monolayer molecular adsorption for LC. The adsorption kinetic data was well described by the pseudo-second-order kinetics model, suggesting that the chemical process could be the rate-limiting step in the adsorption of LC. The selectivity study displayed the excellent selective recognition for LC compared to structural analog and non-analog in unitary and binary solutions. Furthermore, the satisfying regeneration capability of the sorbents was proved by at least three repeated adsorption–desorption cycles.