Facile synthesis of Fe3O4@COF covalent organic frameworks for the adsorption of bisphenols from aqueous solution

Magnetic covalent organic framework modified by Fe3O4 nanoparticles (Fe3O4@COF) were facile synthesized and used as adsorbent for the adsorption of bisphenols from aqueous solutions. The Fe3O4@COF is synthesized by catalyst-free Schiff base reaction of melamine and terephthalaldehyde, and synthesis strategy is flexible and controllable. The as prepared Fe3O4@COF was characterized by TEM, PXRD, TGA and BET analysis. The Fe3O4@COF possessed large specific surface area (335.2 m2/g), high chemical and thermal stability, and high saturation magnetization (49.6 emu/g), which in favor of rapid magnetic separation and efficient adsorption in the adsorption process. The effects of temperature, adsorbent dosage, pH and salt concentration on the adsorption of bisphenols (BPA and BPAF) were studied. The as-prepared adsorbent showed an excellent adsorption ability for BPA and BPAF, and the max adsorption capacity of BPA and BPAF could reach 140 and 290.4 mg/g. The adsorption kinetic fitted the pseudo-second-order kinetic model and the adsorption isotherm followed the Freundlich isotherm equation. Moreover, the Fe3O4@COF presented favorable re-use performance, which kept over 81.4% removal efficiency of bisphenols after five consecutive recycles. The high adsorption performance and reusability make the Fe3O4@COF a promising adsorbent for the removal of bisphenols.