High removal of methyl blue over copper mixed-triazolate MOF by both adsorption and photodegradation from aqueous solution

Abstract

Copper mixed-triazolate MOFs (CuMtz-3a and CuMtz-3b) containing mixed-ligands (3,5-diphenyl-1H-1,2,4-triazole and 1H-1,2,4-triazole) were prepared and showed enhanced adsorption property towards the adsorption of methyl blue (MB) in comparison with the mono-ligand MOF (CuTz-1). The adsorption capacity (152 mg g−1) of CuMtz-3b is 182% that of the parent MOF CuTz-1. Moreover, CuMtz-3b demonstrated remarkable photocatalytic rate constant (0.031 min−1) in comparison with other reported MOFs and inorganic materials on the degradation of MB. The improvement on the photocatalytic property can be attributed to the higher light absorption ability as well as the separation of charge carriers. Mechanism study shows that the ·O2− radical plays a key role in the reaction. More importantly, the high degradation efficiency of MB over CuMtz-3b can be maintained while preserving the crystallinity and morphology of the catalyst after four cycles of processes, indicating that CuMtz-3b is a reusable and stable material towards the photodegradation of MB.