The accumulation of plastic waste has led to severe environmental concerns, highlighting the urgent need for sustainable recycling solutions. Among various plastics, polyethylene (PE) is the most prevalent but remains difficult to upcycle due to its chemical inertness, requiring energy-intensive processes. In this study, we introduce a hybrid approach that integrates chemical and biological processes to convert PE waste into the biodegradable polymer poly(3-hydroxybutyrate) (PHB). This method employs a heterogeneous CeO₂ catalyst to promote mild oxidative depolymerization under environmentally friendly conditions using oxygen and water, generating oxygenated intermediates suitable for microbial conversion. The heterogeneous catalyst minimizes metal contamination and enhances process efficiency by enabling easy separation of reaction products. The resulting oxidized PE derivatives were then used as a sole carbon source for Cupriavidus necator H16, which converted them into PHB. This integrated system achieved a maximum PHB yield of 0.28 g per gram of HDPE waste, marking a significant improvement over previous hybrid PE upcycling methods. The strategy aligns with green chemistry principles by reducing energy consumption and avoiding harsh reagents while offering a viable pathway for closed-loop plastic upcycling. Further optimization of catalyst selectivity and microbial metabolism could enhance yield and broaden the scope of biodegradable polymer production from plastic waste.
