Extruded biodegradable PHBH/PBAT composites functionalized with walnut shell-derived carbon dots for sustainable antioxidant packaging

초록

Reducing agricultural by-products and upcycling them into high-value-added functional materials is a crucial strategy for achieving environmental sustainability in the food industry. Therefore, this study aims to engineer a sustainable, high-performance antioxidant packaging film based on a PHBH/PBAT blend reinforced with upcycled walnut shell-derived carbon dots (wCDs) via a scalable extrusion. We hypothesized that wCDs could serve as multifunctional nanofillers, enhancing the physicochemical barrier and antioxidant properties of the PHBH/PBAT matrix. wCDs were synthesized from walnut shell waste through a green hydrothermal method and exhibited zero-dimensional morphology with excellent radical-scavenging activity. wCDs were then incorporated into the PHBH/PBAT matrix using twin-screw extrusion, serving as multifunctional nanofillers. The resulting nanocomposites exhibited excellent UV-blocking capabilities, reducing UV transmittance to near-zero levels, and improved oxygen-barrier properties, increasing the oxygen-barrier property by approximately 21% relative to the neat blend. Furthermore, the wCDs imparted strong antioxidant activity to the films, with the 3.0 wt% loaded film scavenging 96.5% of ABTS radicals. The practical efficacy was confirmed through food application tests using extra-virgin olive oil, in which the nanocomposite pouches significantly suppressed lipid peroxidation during storage. These findings demonstrate that integrating biowaste-derived wCDs into biodegradable polymers via scalable extrusion offers a promising, eco-friendly strategy for oil packaging that extends the oxidative shelf life of oily food products.

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