Guanidinium-based 3D cationic covalent organic frameworks with different amino modifications for the efficient removal of hexafluorobisphenol A

As a typical endocrine disruptor, hexafluorobisphenol A (BPAF) in water bodies can cause great harm to human health and ecological environment. It is therefore important to remove BPAF from water. Three-dimensional ionic COFs (3D iCOFs) are very promising materials in the field of adsorption due to their advantages in surface area and adsorption sites. In this study, two different amino-modified 3D iCOFs (DG-TFS and TG-TFS) were prepared via a solvothermal method for the efficient removal of BPAF from water. According to Langmuir model, the theoretical adsorption capacities of BPAF by DG-TFS and TG-TFS were as high as 1250 mg g −1 and 1193 mg g −1 , respectively. The ultra-high adsorption capacity was attributed to the multiple interactions between 3D iCOFs and BPAF, including hydrogen bonding, hydrophobicity, π-π stacking, electrostatic interactions, and anion exchange. Despite its smaller specific surface area, DG-TFS exhibits a higher adsorption capacity, which can be attributed to its higher charge density. In addition, both DG-TFS and TG-TFS showed good stability and reusability. The removal of BPAF remained above 91 % and 89 % after six cycles, respectively. The excellent adsorption performance was maintained in real water and fruit samples, achieving over 90 % of that in pure water. This study explored the ability of three-dimensional iCOFs as solid adsorbents for BPAF adsorption in real environmental samples, providing a promising strategy for the adsorption of organic pollutants in environmental remediation.