Preparation of Microfibrillated Cellulose/Chitosan–Benzalkonium Chloride Biocomposite for Enhancing Antibacterium and Strength of Sodium Alginate Films

The nonantibacterial and low strength properties of sodium alginate films negatively impact their application for food packaging. In order to improve these properties, a novel chitosan–benzalkonium chloride (C–BC) complex was prepared by ionic gelation using tripolyphosphate (TPP) as a coagulant, and a biocomposite obtained through the adsorption of C–BC complex on microfibrillated cellulose, MFC/C–BC, was then incorporated into a sodium alginate film. The TEM image showed that the C–BC nanoparticles were spherical in shape with a diameter of about 30 nm, and the adsorption equilibrium time of these nanoparticles on the surface of MFC was estimated to be 6 min under the driving forces of hydrogen bonds and electrostatic interactions. According to the disc diffusion method, the MFC/C–BC biocomposite-incorporated sodium alginate film exhibited remarkable antibacterial activity against Staphylococcus aureus and certain antibacterial activity against Escherichia coli. The strength tests indicated that the tensile strength of the composite sodium alginate film increased about 225% when the loading of MFC/C–BC biocomposite was 10 wt %. These results suggested that the MFC/C–BC biocomposite-incorporated sodium alginate film with excellent antibacterial and strength properties would be a promising material for food packaging, and the MFC/C–BC may also be a potential multifunctional biocomposite for other biodegradable materials.