A fluorescent sensor utilizing quinoline-functionalized UiO-66 for the detection and removal of zinc ions from aqueous solutions

Abstract

Herein, a quinoline-functionalized metal–organic framework fluorescent nanohybrid, UiO-66-AQ, was prepared and thoroughly characterized using a range of analytical techniques. As a representative small-molecule fluorescent sensing group, the quinoline chromophore endows the UiO-66 material with the unique ability to selectively detect and adsorb Zn(II). When excited at 330 nm, the fluorescence intensity of UiO-66-AQ at 423 nm increased by nearly 3.0-fold, demonstrating its notable sensitivity to Zn(II) in an aqueous solution at pH 6.0. The fluorescence detection method exhibited a linear range of 0 to 5.5 mg L⁻¹, and it was capable of detecting concentrations as low as 3.5 μmol L⁻¹. Notably, the presence of other cations did not affect the detection selectivity of the nanoprobe. Moreover, adsorption studies revealed that Zn(II) uptake by UiO-66-AQ was found to follow the pseudo-second-order kinetic and the Langmuir isotherm models, achieving a maximum theoretical adsorption capacity of 49.8 mg g⁻¹. Additionally, the material showed exceptional adsorption and optical responsive repeatability. In summary, the UiO-66-AQ nanohybird represents a novel and effective approach for the simultaneous detection and removal of Zn(II) in aqueous systems.