Facile synthesis of recyclable magnetic covalent organic frameworks for adsorption of bisphenol A from aqueous solution

Bisphenol A (BPA), as a common endocrine disruptor, is widely present in water environment. It can migrate into food and gradually accumulate in organisms, posing potential health threats to humans. Herein, covalent organic frameworks (COFs) with different pore sizes (15.56 Å for TpPa-2, 21.95 Å for TpBD, and 30.29 Å for TFPB-BD) were synthesized by solvothermal reaction. The corresponding magnetic COFs (MCOFs) were conveniently prepared by co-precipitation method and were used for adsorption of BPA. The adsorption capacity of Fe 3 O 4 /TpPa-2, Fe 3 O 4 /TpBD, Fe 3 O 4 /TFPB-BD reached 44.85, 24.14 and 2.61 mg g −1 respectively, that is Fe 3 O 4 /TpPa-2>Fe 3 O 4 /TpBD>Fe 3 O 4 /TFPB-BD. The adsorption kinetic fitted the pseudo-second-order kinetic model and the adsorption isotherm fitted the Freundlich isothermal model. Both models demonstrated that the adsorption of BPA is based on heterogeneous surface. In addition, recycling experiments indicated that after five cycles of adsorption/desorption, the adsorption capacity can still reach 76.39% of the first use, indicating that recyclable Fe 3 O 4 /TpPa-2 is a potential adsorbent and can be further applied to the adsorption of environmental pollutants.