Preparation of fluorinated covalent organic polymers at room temperature for removal and detection of perfluorinated compounds

Abstract

Covalent organic polymers (COPs) are promising adsorbents for the removal and detection of various types of pollutants. However, the preparation of COPs that exhibit uniform dispersion and good appearance at room temperature is challenging. Herein, fluorinated covalent organic polymers (F-COPs) with different morphologies were synthesized through the Schiff base reaction of 4,4-diamino-p-terphenyl (DT) and 2,3,5,6-tetrafluoroterephthalaldehyde (TFA). The as-prepared F-COPs could selectively adsorb perfluorinated compounds (PFCs) owing to their fluoro-affinity, hydrophobicity, hydrogen bonding, and electrostatic attraction. The adsorption kinetics and isotherm simulation results showed that the adsorption process conformed to the second-order kinetics and the Langmuir model. The saturated adsorption capacity calculated by the Langmuir model was found to be 323-667 mg/g. The F-COPs were applied to the treatment of simulated fluorine industrial wastewater, and the PFC removal efficiencies of 92.3-100.0% were achieved. Moreover, ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS) was conducted for the detection of trace-level PFCs using F-COPs as dispersive solid-phase extraction (DSPE) adsorbents. The limits of detection were 0.05-0.13 ng/L and the limits of quantification were 0.17-0.43 ng/L. This study facilitates the synthesis of COPs at room temperature and extends the application of COPs as pretreated materials for environmental remediation and detection.

Keywords: Adsorption; Covalent organic polymers; Environmental detection; Fluoro-affinity; Ultra-high-performance liquid chromatography–mass spectrometry.