Spatial Confinement Nanoreactors Enable Synergistic Catalysis for Polyethylene Terephthalate-Derived Ethylene Glycol Oxidation

Abstract

The widespread use of polyethylene terephthalate (PET) in textiles and packaging has led to a significant amount of microplastic pollution in wastewater, posing serious threats to ecological security and human health. The effective remediation of PET microplastic pollutants has become an urgent task in the field of polymer environmental protection. Peroxymonosulfate (PMS)-based advanced oxidation processes have emerged as a promising technology for microplastic remediation due to their strong oxidation capacity. However, they still face the challenge of insufficient reactive oxygen species (ROS) catalytic efficiency, and Fe-based catalysts suffer from Fe leaching. Herein, we constructed Fe/Fe3C@C yolk–shell spatial confinement nanoreactors for multi-ROS synergistic catalytic reforming of PET microplastics. The unique nitrogen-doped carbon shell forms a physical encapsulation barrier that spatially isolates the Fe/Fe3C active core from the aqueous reaction environment, effectively alleviating the Fe leaching problem, thereby enhancing catalyst stability and minimizing secondary environmental pollution caused by metal ion loss. Meanwhile, the Fe/Fe3C active core serves as the primary site for efficiently activating PMS and generating singlet oxygen (1O2), sulfate radical (SO4•–) and hydroxyl radical (•OH). The synergistic effect of these ROS can not only achieve highly efficient decomposition of organic pollutants with the MO degradation efficiency of about 95% but also efficiently oxidize the ethylene glycol (EG)-derived from PET into formate (FA) with a yield of 21.35 mM. The spatial confinement effect of the nanoreactor optimizes the material transfer process and the local reaction microenvironment, reducing the recombination of ROS and improving mass transfer efficiency. Moreover, this effect concentrates reactants and ROS within the confined space, thereby further enhancing the synergistic catalytic performance for the reformation of PET microplastics. This work provides a reference for the development of high-performance spatial confinement nanoreactors for microplastics degradation and organic pollutant treatment, promoting the sustainable development of polymer environmental protection.