Fabrication and Evaluation of Magnetic/Hollow Double-Shelled Imprinted Sorbents Formed by Pickering Emulsion Polymerization

Magnetic/hollow double-shelled imprinted polymers (MH-MIPs) were synthesized by Pickering emulsion polymerization. In this method, attapulgite (ATP) particles were used as stabilizers to establish a stable oil-in-water emulsion, and a few hydrophilic Fe3O4 nanoparticles were allowed to be magnetic separation carriers. The imprinting system was fabricated by radical polymerization in the presence of the functional and polymeric monomers in the oil phase. The results of characterization indicated that MI-MIPs exhibited magnetic sensitivity (M-s = 4.76 emu g(-1)), thermal stability (especially below 200 degrees C), and hollow structure and were composed of exterior ATP shells and interior imprinted polymers shells. Then MH-MIPs were evaluated as sorbents for the selective binding of lambda-cyhalothrin as a result of their magnetism, enhanced mechanical strength, hydrophilic surface, and recognition ability. The kinetic properties of MH-IPs were well described by the pseudo-second-order equation, indicating that the chemical process could be the rate-limiting step in the adsorption process for lambda-cyhalothrin. The equilibrium adsorption capacity of MH-MIPs was 60.06 mu mol g(-1) at 25 degrees C, and the Langmuir isotherm model gave a better fit to the experimental data, indicating the monolayer molecular adsorption for lambda-cyhalothrin. The selective recognition experiments also demonstrated the high affinity and selectivity of MH-MIIPs toward lambda-cyhalothrin over fenvalerate and diethyl phthalate.