Optimizing cellulose microfibrillation with NaOH pretreatments for unbleached Eucalyptus pulp

Abstract

Microfibrillated cellulose (MFC) is a form of biopolymer that stands out because of its versatile use. However, the process of obtaining MFC requires adjustments to provide the increase of microfibrillation in industrial scale. Thus, this study aimed to apply pretreatments with NaOH in unbleached Eucalyptus sp. fibers to optimize the microfibrilation process, in order to evaluate the effect of drying and not drying the fibers after pretreatments for reduction of energy consumption. Treatments of MFC with NaOH at 5% with 2 h of reaction and by 10 wt% were evaluated for the resulting morphology, chemical composition, and energy consumption. The length and width of the pulp fibers pretreated with NaOH decreased significantly, mainly with hasher pretreatments. Pretreating fibers with 5 wt% NaOH for 2 h increased the water retention value (WRV), in addition to presenting the lowest energy consumption for fibrillation, promoting energy savings of up to 48%. Pulps that were non-dried after the NaOH pretreatments resulted in easier microfibrillation and lower energy consumption when compared to dried pulp, which shows the negative impact of drying on the fibers to obtain MFC.