Core-shell superparamagnetic Fe3O4@β-CD composites for host-guest adsorption of polychlorinated biphenyls (PCBs)

The effective recognition and enrichment of trace polychlorinated biphenyls (PCBs) in the environment are currently challenging issues due to human health concerns. In this paper, a surface absorptive layer coating superparamagnetic Fe3O4 nanoparticles for PCBs enrichment were prepared. This protocol involved the synthesis of Fe3O4 particles through a solvothermal reaction and the covering of a silica layer bonded β-cyclodextrin (β-CD) over Fe3O4 via a sol-gel process to construct core-shell Fe3O4@β-CD composites. β-CD was linked covalently to Fe3O4 nanoparticles to generate the binding sites, enhancing the stability of Fe3O4 nanoparticles in water. Meanwhile, superparamagnetic Fe3O4 core could be rapidly separated from matrix to simplify time-consuming washing extraction. The adsorption capacity of Fe3O4@β-CD composites to PCB28 and PCB52 in aqueous solutions was investigated. To estimate the theoretical binding site number of Fe3O4@β-CD, the obtained binding data were replotted according to Scatchard equation. The host-guest interaction between β-CD and PCBs were further examined with density functional theory (DFT) calculations. It provides theoretical evidence of β-CD as host molecule has a higher binding amount towards PCB-28 than PCB-52 on the basis of their optimized geometries and calculated complexation energies. The nanomaterial reported herein is an ideal candidate for various applications, including the recognition and removal of environmentally deleterious substances.