Recycling of polyethylene terephthalate to bismuth-embedded bimetallic MOFs as photocatalysts toward removal of cationic dye in water

Our study presents a sustainable approach to fabricating efficient photocatalytic metal–organic frameworks (MOFs) by recycling polyethylene terephthalate (PET) waste from bottles. Through chemical depolymerization, recycled terephthalic acids (BDCs) obtained from PET waste were coordinated with copper (Cu) and nickel (Ni) to prepare a bimetallic Ni/Cu-MOF. After exploring various Ni:Cu ratios (1:3, 2:3, and 3:3), we determined that the 2:3 ratio represents the optimal metal combination (degradation efficiency 50–60% under direct sunlight). Subsequently, we integrated bismuth oxyiodide (BiOI) into the Ni/Cu-BDC MOF, yielding Ni/Cu-MOF@BiOI heterostructures. Thorough structural characterization via scanning electron microscopy and X-ray diffraction confirmed the morphology and composition of the prepared materials. Assessing the photocatalytic performance against MB degradation in water under solar irradiation, we systematically analyzed operational parameters such as pH, catalyst dosage, MB concentration, and irradiation time. Ni/Cu-MOF@BiOI heterostructures exhibited exceptional efficiency, degrading 99% of MB under sunlight in four hours. Our research presents a sustainable method for the synthesis of photocatalysts using recycled PET waste, along with optimized operational parameters for enhanced catalytic efficiency. This approach combines green synthesis, material hybridization, and thorough analysis, contributing significantly to sustainable materials for pollutant remediation.