Waste-to-sensor upcycling of polyethylene terephthalate over Ag/Zr-MOF photocatalyst for microplastic degradation and AI-assisted heavy metal detection

Abstract This study aims to develop an integrated waste to sensor platform that couples photocatalytic PET depolymerization with on stream quantification of coexisting heavy metals. We achieve this by preparing AIM-202 through surface coordination of Ag to a water stable Zr-aspartate MOF (MIP-202), creating Ag 0 /Ag δ+ electron sink sites that enhance charge separation and reactive oxygen species generation while preserving the parent framework. The material was characterized by FT-IR, XRD, XPS, photoluminescence, KPFM, and EPR, and its photocatalytic activity was evaluated under Xe lamp irradiation. AIM-202 (5 mg mL–1) oxidized PET with increased FT-IR oxidation indices and surface pitting, and generated soluble products that increased from 151.40 µmol (week 1) to 277.27 µmol (week 2), corresponding to 11.63% and 28.68% conversion to quantified byproducts. The PET derived fluorophore 2-hydroxyterephthalate enabled fluorescence quenching based Cu 2+ and Fe 3+ sensing, and physics guided models refined with lightweight machine learning provided robust concentration back calculation. The novelty lies in a closed loop design in which MOF mediated depolymerization simultaneously produces the sensing reporter and enables data assisted quantification, supporting scalable remediation and monitoring within a single integrated scheme.