Investigation of Congo Red Photodegradation Catalyzed by MOFs ZIF-67@SiO2 Composite Under Sunlight

Metal-organic frameworks (MOFs) ZIF-67 and ZIF-67@SiO2 composites were synthesized using a solvothermal method combined with in situ impregnation at varying SiO2 concentrations (4%, 8%, and 12% by weight). Phase identification, crystal structure, morphology, particle size, texture properties, and microporosity of the materials were analyzed using XRD, FTIR, Raman spectroscopy, SEM-EDS, and BET techniques. The photodegradation performance of Congo red in an aqueous solution was evaluated by measuring adsorption capacity and degradation percentages for ZIF-67 and ZIF-67@SiO2 composites with different SiO2 concentrations and contact times. Phase and crystal structure analyses confirmed the formation of the crystalline ZIF-67 phase, with variations in crystallinity. FTIR and Raman spectroscopy indicated that the addition of silica did not damage the ZIF-67 structure. Surface morphology analysis revealed that ZIF-67 and its composite particles exhibited a rhombic dodecahedron shape, with particle size increasing as silica content increased. The ZIF-67@SiO2 (8%) composite demonstrated the highest photodegradation performance for Congo red under sunlight, achieving a degradation percentage of 72.79% and following pseudo-second-order adsorption kinetics.