A sustainable synergistic strategy for photocatalytic and -mediated biodegradation of TiO₂-incorporated LDPE with agricultural valorization.

Plastic pollution, particularly from low-density polyethylene (LDPE), represents a major global environmental challenge due to its persistence and resistance to natural degradation. In this study, a novel synergistic strategy combining photocatalytic oxidation and microbial biodegradation was developed to enhance LDPE degradation. Rutile titanium dioxide (TiO₂) nanoparticles were synthesised via an eco-friendly sol - gel method and incorporated into LDPE at a concentration of 5 wt% to fabricate photocatalytically active composite films. Plastic-degrading bacteria isolated from plastic-contaminated soil were identified through 16S rRNA gene sequencing as Bacillus velezensis (NCBI Accession: PP499256). The LDPE-TiO₂ composite exhibited significantly enhanced degradation under visible light irradiation, achieving 85% weight loss within 21 days in the presence of B. velezensis, compared with 71% under ultraviolet irradiation and substantially lower degradation in untreated LDPE controls. Fourier Transform Infrared (FTIR) spectroscopy confirmed oxidative degradation through the formation of carbonyl functional groups, while Gas Chromatography-Mass Spectrometry (GC-MS) analysis identified degradation products including acetic acid, propanoic acid, octadecanoic acid, and erythritol, indicating progressive polymer oxidation and microbial metabolism. Furthermore, plant growth experiments using wheat, fenugreek, and green gram demonstrated enhanced germination, root elongation, and chlorophyll content without phytotoxicity. This integrated approach offers a sustainable strategy for plastic waste remediation and valorisation within a circular bioeconomy framework.