Insights into the immobilization mechanism of tannic acid on bamboo cellulose fibers

Tannin acid (TA), as a natural water-soluble plant polyphenol, has been widely used to realize the functionalization of cellulose-based plant fibers, such as flame retardant, antibacterial and heavy metal adsorption. However, the interaction mechanism between TA and the main component of these fibers-cellulose, remains unclear. In this paper, bamboo cellulose fibers (BCFs) were used as the substrates to immobilize TA under different environmental conditions to investigate their interaction mechanisms. The results showed that the immobilization of TA on BCFs was multi-molecular layer reversible physical adsorption and the main driving force of this process was the hydrogen bonds in non-covalent bonds. In addition, the interaction between TA and BCFs was related to pH, and pH = 5 was the optimal immobilization condition where BCFs had a maximum TA adsorption capacity of 230 mg/g, considerably higher than other substrates. We believe that the elaboration of this immobilization mechanism can provide a theoretical basis for the preparation of multifunctional materials based on TA modified cellulose fibers in the future.