Enhanced visible-light photo-fenton-like degradation of microplastics using nitrogen-doped TiO2 and cobalt Prussian blue analogue

Abstract

Microplastic pollution is a global concern infiltrating every aspect of our environment and food chain. Conventional wastewater treatment plants (WWTPs) are ineffective at removing microplastics (MPs), necessitating advanced degradation approaches. Among various techniques, Fenton and photo-Fenton processes emerge as promising solutions. Here, photo-Fenton-like degradation was studied using nitrogen-doped titania (N-TiO 2 ) nanorods decorated with cobalt Prussian blue analogue (N-TiO 2 /CoPBA) as a visible-light-active photocatalyst. The N-TiO 2 nanorods were hydrothermally grown on glass fiber, followed by CoPBA deposition through co-precipitation. The glass fiber serves the dual function of trapping plastic particles and supporting the photo-catalyst. FTIR was used to monitor the carbonyl index, indicating progressive oxidation. The observed changes are consistent with oxidative degradation and polymer-chain scission; however, the formation of soluble degradation intermediates and the extent of mineralization were not evaluated in the present study. Under visible-light irradiation in a flow-through reactor, photocatalytic and photo-Fenton-like degradation of poly-propylene (PP) MPS were compared, with photo-Fenton-like reactions showing substantial particle volume reduction. Optimizing H 2 O 2 concentration (15 mM, dosing every 24 h) led to a ~90% volume reduction within 48 h while it took several days when H 2 O 2 was not controlled. Post-experiment analysis of the catalyst confirmed its stability, highlighting its potential for long-term application in microplastic removal from water streams.