Metal-polyphenol network loaded ZIF-8 for efficient removal of fluoroquinolone antibiotics

Abstract

A metal-polyphenol network functionalized on surface of zeolitic imidazolate framework-8 (MPN@ZIF-8) were fabricated for efficient removal of fluoroquinolones (FQs) antibiotics. Polyphenol as one kind versatile molecular glue was employed as organic ligand as well as linkage for growth and deposition of metal-polyphenol network (MPN) on ZIF-8 supporter. The prepared MPN@ZIF-8 composite was characterized by various methods. The parameters including the dosage of adsorbents, pH value, adsorption time and salt concentration affecting the adsorption process were systematically investigated. FQs adsorption isotherms and kinetics best fitted the Langmuir isotherm (R2 > 0.980) and pseudo-second-order model (R2 > 0.987), respectively. Thermodynamic studies showed that adsorption process of norfloxacin (NOR), ciprofloxacin (CIP) and enrofloxacin (ENR) were all spontaneous. The adsorption capacity of MPN@ZIF-8 were 104.60, 86.23 and 66.21 mg g−1 for NOR, CIP and ENR, respectively, which were significantly higher than those of precursor ZIF-8. The potential adsorption mechanism was stated, most likely involved in π-π interaction, hydrogen-bond and electrostatic interaction between the FQs and the MPN@ZIF-8. In addition, the removal efficiency of the three FQs on MPN@ZIF-8 was still above 95 % after recycle for four times. The recoveries of the three FQs were in the range of 77.1–100.1 % with RSDs below 7.8 % in real sample analysis. Compared with the methods in preparation of MOF-based composite, the fabrication method mentioned in this study is versatile, very easy, environmental friendly and low cost, which has potential in large-scale production for application in environmental remediation.