Logical Optimization of Metal–Organic Frameworks for Photocatalytic Degradation of Organic Pollutants in Water via Box–Behnken Design

Cobalt/copper-based bimetallic metal–organic frameworks (Co/Cu-MOFs) are synthesized using two organic ligands in the presented research work. Subsequent incorporation of bismuth oxyiodide (BiOI) into the MOFs via a hydrothermal approach formed composite materials (Co/Cu-MOFs@BiOI) that exhibit an efficient photocatalytic activity. The synthesized materials were thoroughly characterized by using X-ray diffraction, Fourier transform infrared, and scanning electron microscopy techniques. Co/Cu-MOF @BiOI was employed as a novel photocatalyst for the degradation of cationic methylene blue (MB) dye in aqueous solution under visible light. The combination of Co/Cu-MOFs with BiOI significantly enhanced the photocatalytic degradation efficiency of MB relative to that of bimetallic MOFs (Co/Cu-MOFs) owing to increased visible light absorption and reduced charge-carrier recombination. A Box–Behnken design (BBD) statistical study is employed in conjunction with response surface methodology (RSM) to optimize the dye degradation process. The BBD-RSM methodology successfully identified the optimal dye degradation conditions, including an initial dye concentration of 6 ppm, irradiation time of 120 min, and catalyst dosage of 0.14 g L–1. Furthermore, the predicted coefficient of regression (R2) value under these optimal conditions using BBD-RSM was 99%, indicating a strong correlation between the prediction and experimental observation. These results demonstrate the strong potential of the Co/Cu-MOF @BiOI composites as efficient photocatalysts for the removal of organic dyes.