Visible light active photocatalytic cellulose acetate/Co-ZnO nanofiber membranes for active food packaging S.D. Deshapriya, Dr. I. Munaweera Department of Chemistry, Faculty of Applied Sciences, University of Sri Jayewardenepura, Gangodawila, Nugegoda, Sri Lanka With the modern civilization’s population growing by the day, hunger and food insecurity have become major issues around the world fueled by food waste caused by deterioration and premature spoilage of food due to improper food transport and storage practices. Therefore, it is urged to design necessary food preservation protocols to enhance the shelf-life of food, inhibiting microbes to result in products absent of pathogenic microbes and controlling excessive metabolic activities of some chemical compounds available in food. Today, it is common practice to add significant amounts of chemical substances to food goods in order to preserve them, which has a variety of unexpected consequences on people. To ensure the continuity of preservation, it is desirable to use active food packaging materials. In this research, it was focused on developing a visible light active photocatalytic electrospun nanofiber membranes embedded with Co doped ZnO (Co-ZnO) to improve the shelf-life of easily perishable fruits, particularly strawberries. Since the ZnO is mainly activated under high energy UV range, to bring it to visible light (VL) range, it was doped with cobalt and the radical species generated by Co-ZnO photocatalyst may aid in the degradation of microbes and controlling the excessive activities of chemical compounds such as ethylene in strawberries to improve the shelf-life. In order to synthesize undoped ZnO nanoparticles (NPs) and Co-ZnO nanorods with Co: Zn atomic ratios of 5%, 10%, 15% and 20%, co- precipitation approach was utilized. Powder X-ray Diffraction (PXRD) and Raman spectroscopy proved the successful synthesis of wurtzite structure of prepared NPs. PXRD, X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDX) supported to ensure the successful incorporation of Co into ZnO lattice. Scanning Electron Microscopy (SEM) analysis conveyed the spherical shape of ZnO NPs and the change in the shape from spherical to rod- shaped upon doping Co. Diffuse Reflectance Spectroscopy (DRS) exhibited the shift of band gap energy from UV range to VL range which is a red shift from 3.26- 3.01 eV upon increasing Co concentration. The photocatalytic activity of NPs was examined, utilizing the degradation of methylene blue under sunlight and 50 W LED lamp. The most efficient photocatalyst was found to be 15% Co-ZnO and it is 40% degradation under sunlight and 24% degradation under lamp for one-hour period. 15% (w/w) Co-ZnO was incorporated into the cellulose acetate (CA) polymer matrix, utilizing the electrospinning process to develop nanofiber membranes. The created CA nanofiber mat with Co-ZnO was employed to extend the shelf life of strawberries, using control mats as well. It was discovered that the shelf life was increased up to 18 days in the optimized Co-ZnO nanofiber mat, along with the reduced pH increase and lower reduction of weight, firmness, and titratable acidity.
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