Abstract: A fluorescence strategy was constructed based on the metallic organic framework Ce-UIO-66-(COOH)₂ was constructed to detect SO₃^2-. Firstly, under solvothermal conditions, the Ce-UIO-66-(COOH)₂ was synthesized using homophthallic acid and Ce⁴⁺ as the organic ligand and central ion. The structure was characterized by XRD, IR, XPS, SEM and EDS. Employing a reaction system using Ce-UIO-66-(COOH)₂, SO₃^2- and benzoic acid, under the catalysis of Ce-UIO-66- (COOH)₂, the SO₃^2- was conversed to sulfate radical SO₄^•−, and then induced benzoic acid to transform into fluorescent molecule 2-hydroxybenzoic acid (salicylic acid), which realizes the detection of SO₃^2-. The detection mechanism was confirmed by fluorescence spectrum and ESR. The influences of time, temperature, dosages of MOF and benzoic acid were explored. Under the optimal conditions, a linear detection range was obtained as 40~120 mM, and the detection limit was 8.3 ?M. The method possesses favourable anti-interference property for common inorganic anions. Meanwhile, it was applied to the determination of SO₃^2- in rainwater and tap water samples, the results are satisfactory.

Key words: UIO-66-(COOH)₂, Radical-Mediated Reaction, Sulfur Dioxide (SO₂), Sulfite Species (SO?2?)