Core-shell molecularly imprinted polymers based on magnetic chitosan microspheres for chloramphenicol selective adsorption

Novel magnetic molecularly imprinted polymers (MMIPs) were prepared based on magnetic chitosan microspheres via a simple and effective method; the obtained MMIPs were used for selective recognition and fast separation of chloramphenicol from water. Fe₃O₄ nanoparticles were uniformly wrapped into the chitosan by emulsion cross-linking method. Imprinted polymerization directly occurred on the surface of microspheres, and core-shell imprinted polymers were developed via in situ precipitation polymerization. The properties of obtained MMIPs were characterized by scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, X-ray diffraction, FT-IR, thermogravimetric analysis, and so on. The adsorption equilibrium data were well described by Langmuir isotherm model. Kinetic studies of adsorption showed that the equilibrium was reached within 60 min, and the pseudo-second-order kinetic model was used to fit the adsorption data well. This work can be regarded as a perfect combination of selective adsorption and magnetic separation, and the obtained MMIPs showed specific recognition and selectivity for chloramphenicol in the presence of competitive antibiotics. The obtained MMIPs showed good stability and regeneration property, which could be one of the most promising candidates for environmental pollution application.