One of the important research fields is the efficient elimination of pollutants from wastewater due to its ecological and environmental importance. Metal organic frameworks (MOFs) have emerged as a significant class of porous crystalline materials that various studies have shown the promising applications of MOFs in catalytic and photocatalytic areas. In this work a mesoporous MOF known as TMU-16, [Zn2(BDC)2(4-bpdh)].3DMF (BDC= 1,4-benzendicarboxylate, 4-bpdh: 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene, DMF: N,N′-dimethylformamide), was employed as a heterogeneous catalyst to photodegradation of azo dyes from aqueous solution under sunlight. Complete degradation occurred just by 40 mg of TMU-16 for solution of each dyes with 20 ppm concentration without auxiliary oxidants such as H2O2. In the case of Congo red 96% degradation occurred after 1 h. Eriochrome Black T and Methyl orange after 3 h and 5 h show 97% and 82% degradation, respectively. The kinetic of dye degradation follows the first- and second-order models. For Eriochrome Black T, the rate is completely second-order, while for Congo red and methyl orange, as long as the dye concentration is high, it is a second-order, but with decreasing concentration, the rate model deviates from the second-order and fits by first-order model. Using 2-hydroxyterephthalic acid as a fluorescent probe confirmed the reaction mechanism is performed by mediated hydroxyl radicals. Excellent reusability and high degradation efficiency recommended that, TMU-16 could be efficient visible heterogeneous photocatalyst for degradation of other organic pollutants.
