Application of Lignin from Cellulose Isolation Process in The Fabrication of Chitosan/Lignin Film for UV-Light Blocking and Anti-oxidation

Black liquor released during the kraft pulping process is one of the main drawbacks in the paper and biorefinery industry due to its significant impact on the environment. Despite being employed for the recovery of lignin, a natural UV absorber, the production of high-purity lignin from black liquor required harsh conditions. Also, chitosan is an abundant polymer that can be applied in many industries due to its biodegradability and biocompatibility properties. Therefore, in this study, the production of a biodegradable film from the combination of chitosan and lignin as a UV absorber was investigated to explore its ability without any size modification. The results showed that lignin reduces the film transmittance to UV light to 0% in all samples. While the degradation temperature of chitosan/lignin film rose with the increase of lignin content, the water vapor permeability of the films containing lignin decreased due to the effect of lignin on the obtained films as a filler. The addition of lignin in the chitosan/lignin film sample further boosted the DPPH radical scavenging activity from 56.14% (LN0) to 91.31% (LN2). These materials exhibited considerable potential for preventing bacterial and fungal growth when the LN2 showed a great inhibition rate for E. Coli and C. Abicans of 80.39 and 99.77%, respectively. This study defined thoroughly the process of recycling lignin from harmful waste to create value-added material useful for application in the food industry, contributes to the advancement of converting biomass and waste into sustainable, value-added materials, enhancing resource efficiency from biomass waste, and promotes environmental preservation while reducing the reliance on plastics.