Experimental study on a modified metal–organic framework catalyst for the removal of methylene blue

This study focuses on enhancing the catalytic properties of copper-modified MOF235 (Cu-MOF235) in wet oxidation for methylene blue (MB) removal from aqueous solutions and optimizing process conditions. The impact of variables such as catalyst dosage (0.005–0.02 g), pH (4–10), temperature (20–40 °C), reaction time (5–60 min), and catalyst type (MOF235 and Cu-MOF235) on dye removal is investigated. Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) techniques were used to investigate the structural and physical characteristics of the synthesized catalyst. The statistical approach of the Design of Experiments (DOE) systematically establishes the relationship between process factors and outcomes. Increasing catalyst dosage enhances the active sites for faster degradation of dye compounds; however, diminishing returns may occur. A quadratic model was used to analyze variance, and the optimum process conditions were calculated with 0.019 g of Cu-MOF235 catalyst, a pH of 8.05, a temperature of 37.03 °C, and a reaction time of 26.56 min. Confirmatory tests under these conditions achieved a maximum removal rate of 98.27%. Cu-MOF235 surpasses MOF235 due to its enhanced active sites, robust chemical interactions, surface modifications, potential synergies, catalytic degradation, and altered solution chemistry. This research underscores the significant impact of catalyst modification on dye removal and provides valuable insights for optimizing such processes.

Graphical abstract