Alkaline Pretreatment Facilitate Mechanical Fibrillation of Unbleached Cellulose Pulps for Obtaining of Cellulose micro/nanofibrils (MFC)

Energy expenditure is a limiting factor for the production of cellulose micro/nanofibrils in mechanical processing. This study evaluated the effect of novel alkaline pretreatments on unbleached <i>Eucalyptus</i> sp. pulps (hardwood) and <i>Pinus</i> sp. cellulose (softwood) to facilitate the production of cellulose nanofibrils by mechanical fibrillation and reduce the energy consumed by the mill. Pretreatments with NaOH in concentrations of 5% for 2 h and 10% for 1 h and 2 h and a hybrid pretreatment with 5%/16% NaOH/ H₂O₂ for 2 h were evaluated. The 10% pre-treatment was done at 1 h and 2 h to evaluate the effect of the less aggressive treatment (1 h). The morphology, chemical composition, turbidity of the fibers/suspensions, mechanical properties, fibrillation quality index and energy expended during the fibrillation were evaluated for each pretreatment. The less aggressive pretreatments produced micro/nanofibrils with fewer passes of the pulp through the fibrillator, which effectively facilitated extraction with lower energy consumption. The hybrid pretreatment did not show satisfactory results in reducing energy consumption, and the quality of the nanofibrils produced by this pre-treatment was inferior to the others. This study showed innovation in performing novel and efficient NaOH and hybrid (NaOH/H₂0₂) pretreatments on commercial unbleached pulps to obtain pulp micro/nanofibrils.