The Effect of Oxidation Time and Concentration on Physicochemical, Structural, and Thermal Properties of Bacterial Nano-Cellulose

In this study, the effects of oxidation time and concentration of hydrogen peroxide (H₂O₂) and potassium periodate (KIO₄) on the physicochemical (including FTIR, EDX, CHNO, water absorption-WA, water retention-WR, contact angle, and degree of polymerization), morphological (SEM), mechanical properties (tensile strength and elongation at break), and thermal stability (TGA) of bacterial cellulose (BC) were investigated. Oxidation was confirmed by observing the formation of hemiacetal bonds and carboxyl bonds in FTIR. CH₂ scissoring of the cellulose chain was strongly observed in OBC-H₂O₂-15h-20. Among different oxidized BCs, OBC-KIO₄-24h-0.01 had the higher mechanical properties and degree of polymerization compared with OBC-H₂O₂ samples. SEM observations showed that oxidation reduced tangling of the nanofibers created open structures, and increased water absorption and water retention values. The lowest contact angle was also obtained for OBC-KIO₄-24h-0.01. The onset degradation temperature of OBC-KIO₄-24h-0.01 samples was lower than the OBC-H₂O₂-30h-10 and neat BC samples. Periodate ions attack the cellulose molecules in a specific way producing aldehyde groups, without breaking the polymer chain. According to the characterized properties, OBC-KIO₄-24h-0.01 can be introduced as an optimum mild and selective oxidation treatment for functionalizing with other matters to produce high-value-added materials/composites.