A novel covalent organic framework with abundant N-O-O and N-N-O sites for detection and removal of Zn2+, Cd2+, Pb2+, Cu2+, and Hg2

Here, tripolycyanamide (TPA) and 2,5-dihydroxyterephthalic acid (DDTA) were used to synthesize crystalline covalent organic framework (COF DDTA-TPA ) which was employed to detect and remove heavy metal ions (HMIs). COF DDTA-TPA has abundant N-O-O and N-N-O sites and large specific surface area, which can be used as an excellent adsorbent for HMIs. The detection limits for Zn 2+ , Cd 2+ , Pb 2+ , Cu 2+ , and Hg 2+ were 0.85 nM, 0.096 nM, 0.14 nM, 0.072 nM, and 0.084 nM, respectively. The COF DDTA-TPA was controllably grown on both melamine foam (MF) and macroporous carbon to remove Cd 2+ , Pb 2+ , Cu 2+ , and Hg 2+ effectively, which avoided some defects of traditional COFs powder such as random orientation, easy accumulation, and poor reproducibility. The COF DDTA-TPA /MF was further prepared as a water filter device for the removal of HMIs. In addition, the proposed material can detect and remove HMIs in sewage, soil, and blood serum real samples and showed great potential in environmental remediation.