A sensitive and selective fluorescent sensor for 2,4,6-trinitrophenol detection based on the composite material of magnetic covalent organic frameworks, molecularly imprinted polymers and carbon dots

Abstract

An efficient and rapid fluorescent sensor was developed for the sensitive and selective detection of an environmental pollutant, 2,4,6-trinitrophenol (TNP). The fluorescent sensor based composite material was composed of magnetic covalent organic frameworks (MCOFs), molecularly imprinted polymers (MIPs) and carbon dots (CDs). MCOFs, MIPs and CDs were applied as supporting materials and sorbents, selective sorbents and fluorescent sensor element, respectively. Further, the composite material (MCOFs@MIPs@CDs) was characterized by SEM, TEM, EDS, FT-IR, Zeta potentiometric analysis, XRD, TGA, VSM and the nitrogen adsorption-desorption isotherms. The MCOFs@MIPs@CDs demonstrate good fluorescence properties and stability. When applied for the sensitive detection of TNP, the composite material exhibits good sensitivity for TNP with a LOD of 100 pM, a high imprinting factor of 8.4 (in comparison with MCOFs@NIPs@CDs) and shorter detection time (within 1 min). Moreover, the results of selective experiment further proof that MCOFs@MIPs@CDs have high selectivity to TNP. Finally, the MCOFs@MIPs@CDs based fluorescent method was used to detect TNP in real water samples, and the recoveries (range from 88.7% to 103.4%) demonstrate that the method has the great potential application in the environmental monitoring and evaluation fields.