The MOF-on-MOF hybrids of MIL-101(Fe)@CoZn-ZIFs as efficient catalyst for the removal of deys from wastewater

In this study, MOF-on-MOF hybrids were successfully synthesized by interfacial growth method using CoZn-ZIF as guest MOF and MIL-101(Fe) as host MOF, and then employed as heterogeneous catalysts to activate peroxymonosulfate (PMS) in the degradation of dyes. The hybrids exhibited different morphologies depending on the Co/Zn ratios (10/0, 10/2, 10/10, and 2/10), all of which displayed exceptional catalytic performance. Notably, the hybrid with a Co/Zn ratio of 10/2 showed the highest degradation rate of MB, reaching 100 % removal within 3 min with a k obs value of 452.75 Lg −1  min −1 based on the pseudo-second-order kinetic model. Through EPR characterization and scavenging experiments, it was determined that the degradation of dyes occurred through a combination of radical (SO 4 •-, •OH)and non-radical ( 1 O 2 ) pathways, with 1 O 2 and SO 4 •- playing prominent roles. Various factors such as Co/Zn ratio, catalyst dosage, PMS concentration, initial pH, temperature, and MB solution concentration were systematically investigated to understand their influence on the catalytic performance. Furthermore, the influence of inorganic ions, humic acid (HA), and the reusability and stability of the catalyst was evaluated, demonstrating its potential for practical applications. Overall, this research provides valuable insights into the design and application of MOF-based catalysts for environmental remediation processes.