Hybrid zinc oxide catalysis for photocatalytic degradation of polystyrene microplastics—performance assessment and characterization

Microplastic Polystyrene (PS) poses a significant environmental threat due to their persistent and recalcitrant nature, yet their detection and degradation remain challenging. This study, presents an integrated approach for detecting and degrading PS in water using surface-enhanced Raman spectroscopy (SERS) and Zinc oxide/Hydroxyapatite (ZnO/HAP) based photocatalysts. Silver nanoparticles (Ag NPs) and potassium iodide (KI) were utilized to enhance Raman signals, achieving a strong quantitative analytical performance (R² > 0.95). For degradation, a ZnO/HAP composite was synthesized via co-precipitation and activated under visible LED light, resulting in over 95% PS degradation and 90% chemical oxygen demand (COD) reduction within 72 h. Characterization using SEM, XRD, FTIR, and UV–Vis-DRS confirmed the composite’s structural integrity, bandgap narrowing (~ 2.53 eV), and enhanced photocatalytic performance. Post-degradation analysis showed no significant catalyst deterioration, with reusability over five cycles retaining over 81% PS removal efficiency. The synergistic roles of ZnO and HAP contributed to improved charge separation and surface adsorption. This dual-functional strategy offers a sustainable, cost-effective solution for microplastic remediation in aquatic environments and surpasses conventional UV-dependent catalysts in terms of efficiency, reusability, and operation under visible light.