Porous three-component hybrid hydrogen-bonded covalent organic polymers: Design, synthesis and ciprofloxacin adsorption

Since the great risks posed by fluoroquinolones arise much concerns, it is required a prompt action to establish efficient adsorbents with excellent behaviors for adsorptive removal in remediation management. Herein, three porous three-component hybrid hydrogen-bonded covalent organic polymers were reasonably designed and successfully prepared via orthogonal reactions based on Schiff-base chemistry and hydrogen-bonding. The resulting polymers were used to remove a model fluoroquinolone antibiotic, ciprofloxacin (CIP), from wastewater. The benzene-1,3,5-tricarbohydrazide (BTCH) and 1,3-di(4-pyridyl)propane (BPP) reacted with 4,4'-biphenyldicarboxaldehyde (BPDA) (JLUE-HCOP-7) and exhibited the profound highest adsorption capacity for CIP as 84.03 mg/g, followed by the reaction of BTCH, BPP and terephthalaldehyde (TPA) (JLUE-HCOP-6), and the reaction of BTCH, 4,4'-bipyridine (BPY) and TPA (JLUE-HCOP-5). The adsorption processes were systematically investigated through batch adsorption experiments. Most of the CIP were removed within 12 h; moreover, the kinetic data and isothermal data were well fit with the pseudo 2nd order model and Langmuir model, respectively. In addition, the high adsorption affinity may be attributed to porousness advantage, electrostatic interactions, hydrophobic effect, electron donor-acceptor (EDA) interactions and hydrogen bonding.