Surfactant-accelerated alkaline hydrolysis of waste PET for upcycling into MIL-53Fe catalysts toward enhanced catalytic ozonation

Quaternary ammonium cationic surfactants accelerate the hydrolysis of PET under mild conditions. • Surfactant-accelerated alkaline hydrolysis of waste PET substantially reduces NREU and GWP. • The recovered high-purity TPA could be directly reutilized for the synthesis of MIL-53Fe. • The PET-derived MIL-53Fe/O 3 system exhibits markedly enhanced catalytic ozonation performance. The rapid accumulation of plastic waste has become a major environmental challenge, driving growing interest in upcycling strategies that transform waste polymers into high-value products within a circular economy framework. Among waste plastics, polyethylene terephthalate (PET) is one of the most abundant and widely discarded materials, yet its sustainable valorization remains constrained by the energy-intensive and chemically demanding nature of conventional recycling processes. In this study, a surfactant-accelerated alkaline hydrolysis strategy using dodecyl dimethyl benzyl ammonium chloride (DDBAC, known as surfactant-1227) is developed to enable efficient PET depolymerization under mild conditions, achieving a terephthalic acid (TPA) yield of 99.6% with a purity of 99%. The recovered TPA is directly reutilized as an organic linker for the synthesis of MIL-53Fe via a solvothermal process, yielding an ozonation catalyst denoted as TS-MIL-53Fe. The TS-MIL-53Fe/O 3 system exhibits markedly enhanced catalytic ozonation performance toward the degradation of acid orange 7 (AO-7), with an observed pseudo-first-order rate constant ( k obs ) of 1.11 min −1 , 1.8 times higher than that of the conventional MIL-53Fe/O 3 system. Mechanistic investigations indicate that improved electron transfer characteristics of TS-MIL-53Fe promote ozone activation at Fe sites, leading to significantly increased reactive oxygen species (ROS) generation, particularly singlet oxygen ( 1 O 2 ). The catalyst also demonstrates robust stability and broad applicability for the removal of diverse organic contaminants and the treatment of complex industrial wastewater. This work presents a low-carbon and resource-efficient approach for converting waste PET into high-performance water treatment catalysts, simultaneously contributing to plastic waste valorization and advanced wastewater remediation. Download: Download high-res image (286KB) Download: Download full-size image