Extraction of cellulose nanofiber from bagasse and preparation of cellulose nanocomposites

The aim of this study was to isolate and characterize nanofibrillated cellulose (NFC) from depithed sugarcane bagasse (SCB) via a sulfur-free chemo-mechanical method. The chemical pretreatments were designed in three stages, initially extractives were removed from SCBs based on national renewable energy laboratory (NREL) method, then SCBs were subjected to a pulping process that involved prehydrolysis with deionized hot water and alkaline pretreatment with soda-anthraquinone (AQ) in the mini-batch reactor to produce dissolving pulp. Finally pulps were bleached by elemental chlorine free (ECF) sequences.The pulp was disintegrated by mechanical pretreatment using refining and high-intensity ultrasonication methods. Morphology, size, and molecular structure of obtained NFCs were studied by scanning electron microscopy (SEM). The image analysis showed that the considerable percentage of isolated CNFs had diameter less than 100 nm and their length was about micrometer range. The chemical compositions were investigated using NREL method and fourier transform infrared spectroscopy (FTIR). The alpha cellulose content, kappa number, and water swelling capacity of the bleached and unbleached pulps were estimated. The results showed that during the pulping process, hemicelluloses, and lignin were significantly removed and crystallinity of the pulp increased. Klason lignin was almost totally eliminated during the bleaching process. Prehydrolysed soda-AQ dissolving pulp had the high alpha cellulose content and low kappa number. Because of the dissolution of hemicelluloses and  lignin during pulping process the water swelling capacity of pulp was increased. The obtained CNFs will be used as reinforcement in nanocomposite production.

Keywords: Bagasse; Dissolving pulp; Nanofibrillated cellulose; Microstructure