Surface Activation of PLA and PLA/CeO₂ Films by Atmospheric Plasma for Catalytic Water Treatment

The growing demand for clean water underscores the need for sustainable and efficient technologies to degrade dye pollutants in wastewater. This study evaluates recycled polylactic acid (PLA) films and CeO₂/PLA nanocomposites, both modified by atmospheric-pressure plasma, as catalytic supports for the plasma-assisted degradation of methylene blue (MB). The use of recycled PLA valorizes waste materials and aligns with circular economy principles for environmental remediation. Raman spectroscopy, X-ray diffraction (XRD), and atomic force microscopy (AFM) showed that plasma treatment induces surface chain scission, increases crystallinity by removing amorphous regions, and enhances surface roughness in PLA films. In CeO₂/PLA nanocomposites, plasma exposure increases nanoparticle accessibility while preserving polymer stability. Plasma activation also improves surface wettability in both materials by introducing polar functional groups. Plasma-treated PLA films achieved complete MB degradation (100 ± 2%) within 70 minutes, whereas plasma-treated CeO₂/PLA films displayed rapid initial degradation (~90% within minutes) and reached ~96% after 60 minutes. The high performance of PLA films is attributed to plasma-induced hydrolysis, defect formation, and localized microelectrolysis, which collectively promote heterogeneous redox reactions that accelerate dye oxidation. Remarkably, the plasma-treated PLA film alone showed catalytic efficiency comparable to that of CeO₂ nanoparticles. To the best of our knowledge, this is the first report demonstrating that a polymeric support can directly contribute to dye photodegradation in a plasma-based system. These findings position recycled PLA as a low-cost, environmentally friendly catalytic mediator for plasma-driven advanced oxidation processes, offering a promising route for sustainable wastewater treatment.