Plasma-modified polypropylene films coated with P-doped TiO2 for photocatalytic water purification: effect of plasma parameters on visible-light-driven activity

This study presents an environmentally friendly strategy to develop visible-light-active photocatalytic polypropylene (PP) films through a two-step process: plasma activation and immobilization of phosphorus-doped TiO₂ (PT). While plasma treatment is a well-established method for polymer surface modification, the novelty of this work lies in the use of low-pressure plasma to enable the strong and uniform immobilization of a PT photocatalyst, tailored for visible-light photocatalysis. This solvent-free, low-temperature approach offers a sustainable alternative to conventional chemical or thermal methods. Surface modification and photocatalyst immobilization were confirmed by SEM-EDX, XPS, and contact angle measurements. Plasma treatment in humidified air significantly improved surface hydrophilicity and photocatalyst dispersion, enhancing photocatalytic activity. The optimized sample achieved 58 % methylene blue degradation under visible light and maintained over 50 % efficiency across five cycles, demonstrating durability and reusability. Furthermore, the composite showed outstanding performance under solar light, achieving 99 % lindane degradation. These results underline the potential of this scalable, eco-friendly platform for developing polymer-supported photocatalysts for environmental remediation.