Visible-Light-Active Starch/Poly(vinyl alcohol)/Metalloporphyrin Films Enable Efficient Photocatalytic Degradation of Anti-Inflammatory Drugs in Water

High Resolution Image Download MS PowerPoint Slide The widespread occurrence of pharmaceutical residues in aquatic environments demands robust, reusable, and solar-activated photocatalytic materials that are capable of operating under mild conditions. In this work, we developed biobased Starch/PVA thin films incorporating meso -tetra(phenyl)porphyrin ( TPP ) and its Zn(II) complex ( ZnTPP ) as heterogeneous photocatalysts for the degradation of nonsteroidal anti-inflammatory drugs acetylsalicylic acid (ASA) and ibuprofen (IBU). The porphyrins were immobilized in situ within a citric acid cross-linked Starch/PVA network, yielding hybrid materials with well-defined structural, thermal, and photophysical properties. Comprehensive spectroscopic, thermal, and morphological analyses confirmed the successful incorporation of the porphyrins and revealed distinct polymer–porphyrin interactions, with ZnTPP promoting higher surface roughness and enhanced accessibility to catalytic domains. Under visible-light irradiation, the Starch/PVA/ ZnTPP films exhibited markedly superior photocatalytic activity, achieving up to 93% removal of pharmaceuticals under optimized conditions. Mechanistic studies employing EPR spectroscopy and radical scavengers demonstrated that superoxide radical anion (O 2 •– ) is the predominant reactive oxygen species driving degradation, while swelling, spectroscopic, and topographical analyses correlated catalyst performance with polymer-network hydration and the porphyrin microenvironment. Photocatalytic efficiency was strongly influenced by operational parameters, with optimal activity at neutral pH, intermediate pollutant concentrations, and low catalyst mass. Importantly, the films displayed exceptional operational stability, maintaining their photocatalytic performance over at least 15 consecutive reuse cycles under both artificial white-light and natural sunlight irradiation. Together, these results position the Starch/PVA/ ZnTPP films as a promising, low-cost, and environmentally compatible platform for the visible-light-driven degradation of pharmaceutical contaminants. The combination of renewable polymer matrices, tailored photophysical behavior, and outstanding reusability underscores the potential of this hybrid material as a practical and scalable technology for sustainable water remediation.