Abstract
The accumulation of microplastics in estuarine environments presents a severe ecological threat, demanding highly efficient, sustainable, and stable remediation strategies. In this study, we report the design and synthesis of a novel organic-inorganic hybrid photocatalyst consisting of a Keggin-type polyoxometalate, phosphotungstic acid (PTA), encapsulated within a highly crystalline imine-linked covalent organic framework (TpPa-1) via a template-assisted solvothermal method. The resulting hybrid material, denoted as PTA@TpPa-1, exhibits a well-defined porous structure, enhanced visible-light absorption, and a significant reduction in photogenerated charge carrier recombination due to the synergistic electron-accepting capability of the localized PTA clusters. Photocatalytic evaluations demonstrate that PTA@TpPa-1 achieves 92.4% weight loss of polystyrene (PS) and 78.5% of polyethylene (PE) microplastics (average size ~50 µm) within 48 hours of visible-light irradiation in simulated estuarine waters, outperforming pristine TpPa-1 by a factor of 2.7. Morphological and chemical characterizations confirm that the degradation proceeds via a radical-mediated pathway, transforming high-molecular-weight polymers into harmless low-molecular-weight oxygenated intermediates and, ultimately, carbon dioxide and water. Crucially, the hybrid catalyst shows outstanding chemical and structural stability, maintaining its catalytic efficiency and crystalline integrity across multiple cycles in high-salinity matrices. This work provides a promising, integrated chemical approach for engineering robust hybrid materials for environmental remediation in complex aquatic ecosystems.
