A highly water-stable dual-emission fluorescent probe based on Eu3+-loaded MOF for the simultaneous detection and quantification of Fe3+ and Al3+ in swine wastewater

Abstract

A novel dual-emissive Eu³⁺-loaded metal-organic framework (MOF) is designed and successfully fabricated by introducing 2-hydroxyterephthalic acid (H₂BDC-OH) and Eu³⁺ ions into an UiO-66-type MOF material. The obtained MOF, here referred to as EuUCH, exhibits dual emission at 450 and 614 nm, and both emissions are quite stable in aqueous media in the pH range of 4-11. EuUCH is characterized by a high selectivity and sensitivity toward Fe³⁺ and Al³⁺, which yield different responsive modes. The two emissions of EuUCH are quenched by Fe³⁺; by contrast, only the emission at 450 nm is quenched by Al³⁺ showing a ratiometric fluorescence signal. More importantly, as there is no clear interference between the signals of Fe³⁺ and Al³⁺, EuUCH is successfully utilized for the simultaneous detection of Fe³⁺ and Al³⁺ in their mixtures. In addition, the simultaneous quantification of Fe³⁺ and Al³⁺ is achieved in more complicated swine wastewater with good recoveries. This work provides a water-stable dual-emissive probe and the possibility to achieve the simultaneous quantification of Fe³⁺ and Al³⁺ in complicated environment wastewater.

Keywords: Al(3+); Eu(3+); Fe(3+); Fluorescent probe; Metal–organic framework; Simultaneous quantification.