Gamma Radiation Synthesized Carboxyl-Functionalized Covalent Organic Framework for Multiple Heavy Metal Adsorption

Abstract

Carboxyl groups exhibit great potential in the field of heavy metal adsorption due to their good coordination ability. In this work, acrylic acid was grafted onto covalent organic framework (COF) by a γ-ray radiation grafting approach to obtain a carboxyl-functionalized adsorbent, AA-TbDa-COF, with decent adsorption capacities for multiple heavy metal ions. Infrared spectroscopy and thermogravimetric analysis proved the successful modification of TbDa-COF with carboxyl groups. The porous nanofiber morphology and high accessibility of carboxyl functional groups enable the resultant AA-TbDa-COF fast adsorption of heavy metal within 1~5 min, with capacities for Pb2+, Cd2+ and Cu2+ attaining 127.9, 60.6 and 39.8 mg/g, respectively. The preparation of functional COFs by radiation method is extended to the field of heavy metal treatment, which proves the great potential of radiation-prepared materials in environmental governance.

Keywords: Covalent organic framework, Radiation grafting, Carboxyl functionalization, Heavy metal, Adsorption