Cellulose Extraction From Green Algae, Ulva Ohnoi, and Its Application to PVA-Based Antibacterial Composite Films Incorporated With Zinc Oxide Nanoparticles

Cellulose was successfully extracted from green algae (Ulva ohnoi) by chemical treatments. The contents of holocellulose and alpha-cellulose significantly increased from 37.6% and 3.3% to 82.5% and 63.3%, respectively, after whole extraction treatments. The extracted cellulose (EC) was mixed to polyvinyl alcohol (PVA) to prepare EC/PVA composite films with polyethylene glycol (PEG) or glycerol (GLY) as a plasticizer. The EC/3%PVA composite film showed the highest tensile strength of 54.42 MPa because of the high PVA content. Adding GLY steeply increased the elongation of the EC/3%PVA film from 3.12% to 126.76%, but adding PEG slightly decreased to 2.63%. The EC/1%PVA/PEG composite film showed the highest visible light transmittance of 84.47%, while the addition of zinc oxide nanoparticles (ZnO-NPs) significantly improved UV-blocking properties. In addition, the incorporation of ZnO-NPs on the EC/PVA-based composite films showed excellent antibacterial activity against six Gram-positive and Gram-negative bacteria.