Biodegradable nano composite reinforced with cellulose nano fiber from coconut industry waste for replacing synthetic plastic food packaging

Environmental pollution due to the usage of non-biodegradable synthetic plastic and agro-waste disposal/burning are major issues nowadays. Hence, in the present study, agro-waste (coconut shells) was selected as raw material to synthesize cellulose nanofibers, and it was incorporated into a biodegradable packaging film to enhance its properties. Coconut shell cellulose nanofibers (CNF) were synthesized by a combination of mechanical (ball milling), chemical (acid hydrolysis), and physical (ultra-sonication) methods with an excellent yield of 41.67 ± 1.07%. After each treatment, the crystallinity index was improved, it was 74.38% for the untreated coconut shell powder, and 98.62% for the CNF obtained after ultra-sonication. After chemical treatments, FTIR analysis was done to confirm the removal of non-cellulosic material. The structure and morphology of the nanofiber were concluded from SEM, AFM, TEM, and the size obtained was up to 29 nm. The cellulose nanofibers were then incorporated into polyvinyl alcohol (PVA) polymer matrix with the linseed oil and lemon oil. The essential oil improved the antioxidant properties of PVA-CNF film, and free radicle scavenging activity was 31.52 ± 0.08% upon the addition of oils. Moreover, PVA-CNF-oil-based composite film showed good antimicrobial activity against food-borne pathogens. Hence, it can be used in the preparation of active packaging in the food industry. Similarly, the mechanical and thermal properties of bio nanocomposite film inferred superior quality than neat PVA film. The optical properties of the developed film were on par with polyethylene film. The film also exhibited excellent biodegradability; 87.34 ± 0.91% degradation was obtained on the 45th day. Another major objective of the study was to provide a hydrophobic nature to PVA-based film. It was improved by incorporating essential oil and coconut shell nanofibers; the contact angle measured was 91.3° ± 0.79°. Hence, the prepared bio nanocomposite film is suggested as an alternative material for non-biodegradable food packaging, thereby reducing plastic pollution.