Nitroxoline Azo Dye Complexes as Effective Heterogeneous Catalysts for Color Removal and Degradation of Some Organic Textile Dyes

Abstract

A new azo dye ligand of sulfadiazine with 5-nitro-8-hydroxyquinoline (H2L) and its Cu(II), Mn(II), Co(II), and Ni(II) complexes have been synthesized and characterized using CHN, 1H NMR, EI-mass, inductive coupled plasma, molar conductance, IR, thermogravimetric analysis, magnetic moment measurements, and UV–vis spectra. On the basis of spectral studies and analytical data, the azo dye acts as a monobasic bidentate ligand coordinating to the metal ions via deprotonated OH and azo nitrogen atom. The spectral data showed that the synthesized complexes have octahedral geometry. The application of the obtained chelates in the oxidative decomposition of three different textile dyes (i.e., AB92, AB40, and AB129) in the presence of H2O2 as an oxidant has been studied. The obtained results indicated that the reactivity of catalysts toward the decolorization of AB40 showed the following order: Cu complex > Ni complex > Co complex > Mn complex; the reactions obey the first-order reaction mechanism, and the rate constants were determined.