Carboxyl-Functionalized Covalent Organic Polymer for Removal of Tobramycin and Ofloxacin from Water

The effective removal of hydrophilic pollutants is of vital significance for environmental protection mainly because of the low efficiency of traditional sewage treatment methods. In this work, the cyano-vinylene-linked covalent organic polymer was prepared using 2,2′,2′′-(benzene-1,3,5-triyl)triacetonitrile (BTNA) and 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT) as the Knoevenagel reaction monomers. The cyano group was then hydrolyzed to obtain a carboxyl-functionalized covalent organic polymer (COP-COOH). With good surface area (73.9 m2 g–1) and large channel (∼3.82 nm), TFPT-BTAN-COP-COOH showed fast adsorption equilibrium and high adsorption capacity for tobramycin and ofloxacin via multiple-functional binding sites. Specifically, the electrostatic interaction between the carboxyl group and basic groups (e.g., amino, piperazine, and dihydropyridine) plays a critical role for the selective removal of tobramycin and ofloxacin. The binding energies of TFPT-BTAN-COP-COOH adsorbed tobramycin and ofloxacin calculated using the density functional theory are −59.83 and −35.63 kcal/mol, respectively. For other aminoglycoside and quinolone antibiotics, such as enrofloxacin, norfloxacin, neomycin, and streptomycin, the removal rate can reach over 95% within 30 min using TFPT-BTAN-COP-COOH as the adsorbent. This work explored a promising strategy for the elimination of hydrophilic organic pollutants during environmental remediation.