Zn-based metal organic framework-covalent organic framework composites for trace lead extraction and fluorescence detection of TNP.

A novel dual functional composite (MOF-TpBD) was prepared through solvothermal methods, with excellent Pb ions separation and stable 2,4,6-Trinitrophenol (TNP) fluorescence detection performance. MOF-TpBD was characterized by FTIR, XRD, XPS, SEM and TGA et al. The prepared material was used to extract Pb ions, with an adsorption capacity of 21.74 mg g calculated by Langmuir isotherm model. The limit of detection was 0.32 μg L, along with a linear range from 0.7 to 12 μg L and a precision of 5.4% (1 μg L, n = 9), respectively, where MOF-TpBD was adopted as adsorbent for Pb ions preconcentration. The practical samples and reference water sample were measured by the provided method, with the satisfactory recoveries (91-110%) and reliable analytical results. MOF-TpBD was capable of fluorescent sensing of TNP, with a linear range from 0.01 to 1 mM and a limit of detection of 3.52 μM, respectively, and a precision of 3.29% was obtained (0.2 mM, n = 11). Meanwhile, the recoveries ranged from 91% to 108% in analysis of TNP for the practical samples. The designed material provided a potential candidate material for the detection of heavy metal ions and explosives in environmental water samples.