Microfibrillated cellulose production based on a green solvent biorefinery pulp

GISELLE GONZÁLEZ; NANCI EHMAN; FERNANDO FELISSIA; MARÍA EVANGELINA VALLEJOS; MARÍA CRISTINA AREA

Buenos Aires

Congreso; 11th World Congress of Chemical Engineering; 2023

Green solvent utilization in biorefinery schemes is an alternative to traditional processes. Unlike those commonly used, these solvents adhere to green chemistry principles during their production, and whole life cycle. They can be recovered or disposed of with minimal environmental impact. γ-Valerolactone is one of the most researched green solvents given its recyclability, non-toxicity, high boiling point, solubility in water which contributes to biodegradation, among others.This study evaluated the production of microfibrillated cellulose (MFC) from a sugarcane bagasse pulp obtained by a biorefinery process using an acid-catalyzed organosolv treatment with γ-valerolactone (GVL): Liquid-to-solid ratio of 10, 43 wt% GVL, 0.005 M H2SO4, 155°C, and 90 min [1]. The GVL pulp was then microfibrillated using a recirculating simple disc refiner (disc gap: 0.025 mm). The control was a commercial bleached ECF sugarcane bagasse pulp. Properties of pulps were measured: ISO Brightness (IB), lignin content, and intrinsic viscosity (IV). Rheology behavior (dynamic viscosity), IV, and morphology (using optical microscopy, MO) were measured on MFC suspensions. Diameters in pulps/MFC were determined using Leica QWin software (n=500). GVL pulp achieved a delignification of 72.4%, IB: 36.3% and 12.5% of lignin content. GVL pulping is highly beneficial for the delignification of the material, showing a strategy to reduce steps in bleaching sequences and allow the approach of lignin fraction. Added to these benefits, the low acid load during treatment and the recovery of GVL reduce the environmental impact of the process. The required time to reach a complete microfibrillation was higher for GVL pulp (75 min, Control: 20 min). However, the MO images showed highly microfibrillated systems for both MFC suspensions. The diameter was reduced to 87.4% for GVL pulp and 85.0% for control pulp after passing through the simple disc refiner reaching final average diameter values of 2.37 µm and 2.82 µm respectively. The rheological behavior for both samples was similar and the loss of IV during the microfibrillation stage was minimized, reaching 860 mL/g (MFC GVL) and 733 mL/g (MFC Control). The MFC production from sugarcane bagasse using GVL treatment and simple disc refiner was carried out. The GVL treatment is a highly beneficial process to obtain high delignification pulps and recover the solvents. Adjustment of time during mechanical fibrillation will allow the system to become strategically beneficial for incorporation into biorefinery schemes based on green solvents.