A Novel Smart Microsphere with Magnetic Core and Ion-Recognizable Shell for Pb2+ Adsorption and Separation

Smart core shell microspheres for selective Pb2+ adsorption and separation have been developed. Each microsphere is composed of a Pb2+ recognizable poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (PNB) shell and a magnetic Fe3O4 core. The magnetic PNB core shell microspheres show excellent PP adsorption selectivity among the coexisting Cd2+, Co2+, Cr3+, Cu2+, Ni2+, Zn2+, K+, and Ca2+ ions by forming stable B18C6Am/Pb2+ host guest complexes and exhibit an interesting temperature-dependent Pb2+ adsorption. The inner independent magnetic Fe3O4 cores enable the Pb2+-adsorbed microspheres with a magnetically guided aggregation to be separated from the treated solution using a remotely controlled manner. The isothermal Pb2+ adsorption result fits well with the Freundlich isotherm. The magnetic PNB core shell microspheres show very fast adsorption of Pb2+, and the adsorption process of Pb2+ onto magnetic PNB core shell microspheres fits well with the pseudo-second-order model. Moreover, Pb2+-adsorbed microspheres can be regenerated by simply increasing the operation temperature and washing with deionized water. The proposed magnetic PNB core shell microspheres provide a promising candidate for Pb2+ adsorbents with selectively separable and efficiently reusable abilities.