Exploring lignocellulosic citrus waste as a potential accelerator for the biodegradation of PLA bioplastic in environmental conditions

Plastic pollution is a critical environmental issue, and biodegradable alternatives such as polylactic acid (PLA) have emerged as promising solutions. However, PLA degrades slowly under natural conditions, limiting its environmental benefits. This study investigates the use of a by-product, obtained after pectin and essential oil extraction from orange peel waste, as a natural filler to potentially enhance the biodegradation of PLA under ambient conditions. PLA films with varying filler concentrations (10 %, 20 % and 30 %) were exposed to forest soil microorganisms at room temperature and 50 % humidity. Over 1, 2, and 3 months, the materials were analysed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), wettability measurements, and optical microscopy to assess degradation-induced changes in thermal and structural properties. The results obtained suggest that low filler contents (10–20 %) improve PLA’s environmental resistance, while a 30 % filler promotes its degradation through enhanced surface hydrophilicity and erosion. This dual outcome underlines the need to tailor filler concentrations to balance material performance and environmental disintegration. Overall, this study demonstrates the potential of orange peel-derived lignocellulosic residues to both enhance PLA biodegradability and valorise agro-industrial waste, contributing to the design of sustainable, circular bioplastics.