Designing bimetallic zeolitic imidazolate frameworks (ZIFs) for aqueous catalysis: Co/Zn-ZIF-8 as a cyclic-durable catalyst for hydrogen peroxide oxidative decomposition of organic dyes in water.

ZIF-8 is well known hybrid material that is self-assembled from inorganic and organic moieties. It has several potential applications due to its unique structure. One of these potential applications is in advanced oxidation processes (AOP) a heterogeneous catalysis system. The use of modified ZIF-8/HO for the destruction of the azo dye methyl orange (MO) is presented in this work to explore its efficacy. This work presents the bimetallic Co/Zn-ZIF-8 as an efficient catalyst to promote HO oxidation of the MO dye. Co/Zn-ZIF-8 was synthesized through a hydrothermal process, and the pristine structure was confirmed using XRD, FTIR, and XPS. The Co/Zn-ZIF-8/HO system successfully decolorized MO at the selected pH 6.5. It was found that more than 90% of MO (10 ppm) was degraded within only about 50 minutes. Proposed radical and redox mechanisms are presented for HO decomposition where the redox mechanism is suggested to predominate a Co(ii)/Co(iii) redox consecutive cyclic process.