A Green Approach Based on Reactive Extrusion to Produce Nanofibrillated Cellulose from Oat Hull

摘要

The objectives of this study were (1) to produce nanofibrillated cellulose (NFC) from oat hull by employing simple processes based on reactive extrusion combined or not combined with previous bleaching with peracetic acid, with both processes followed by an ultrasonication step; and (2) to characterize the obtained materials according to their composition, morphology, crystallinity and thermal stability. Oat hull was submitted to two different process: (1) extrusion in three sequential steps: first, with NaOH (10% w/w); then, twice with H_2SO_4 (2% w/w); and finally, an ultrasonication step, which resulted in nanofibers with diameters of 100 ± 25 nm and a yield of 60%; (2) bleaching with peracetic acid, and then one-step extrusion with H_2SO_4 (2% w/w) followed by an ultrasonication step, which resulted in fibers with diameters of 12±2 nm and a yield of 65%. Reactive extrusion and the combination of peracetic bleaching with reactive extrusion were effective in the production of NFC from oat hull, and the main advantages from the proposed methods were simplicity and generation of fewer effluents when compared with those of conventional methods that have been described in the literature.