Synthesis of Cellulose Acetate from Banana Rachis Residues

Banana cultivation generates substantial amounts of lignocellulosic waste that can be used as a renewable source of value-added materials. Although several agricultural byproducts have been investigated as cellulose sources, banana rachis from Tabasco, Mexico, has received limited attention, particularly for cellulose acetate production. In this study, banana rachis was evaluated as a cellulose source through a two-step process comprising cellulose extraction and subsequent acetylation. Two chemical pretreatment methods were compared. Method 2 provided the highest cellulose extraction yield (33%); however, cellulose obtained by Method 1 produced a higher initial acetylation yield (38%) than that obtained by Method 2 (28%). Therefore, Method 1 was selected for process optimization. The isolated cellulose was characterized by Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The results were consistent with the removal of lignin and hemicellulose and showed the expected morphological changes after pretreatment. Cellulose acetate synthesis by iodine-catalyzed esterification was optimized using an experimental design. Acetic anhydride and iodine concentrations were identified as the main factors affecting reaction yield. The optimal conditions were 9 equivalents of acetic anhydride, 0.5 equivalents of iodine, 80 °C, and 1 h of reaction time, resulting in an average yield of 76%. Cellulose acetate formation was confirmed by FTIR and ¹H NMR spectroscopy, and a degree of substitution of 2.45 was determined, indicating a high level of acetylation. These results demonstrate the potential of banana rachis from Tabasco as a renewable raw material for cellulose acetate production.