Efficient pretreatment using dimethyl isosorbide as a biobased solvent for potential complete biomass valorization

An efficient and sustainable pretreatment, such as organosolv pretreatment that produces high-quality lignin and highly digestible carbohydrates, could enable the potential complete utilization of lignocellulosic biomass. Demand for bio-based solvents with a high boiling point, low viscosity, and negligible toxicity is increasing. Herein, we report the use of dimethyl isosorbide (DMI) as a solvent to fractionate lignocellulosic biomass into its main components for the first time. High lignin removal efficiency (91.2%) with good cellulose retention (around 80%) could be achieved during the pretreatment of Eucalyptus by DMI/H2O co-solvents under a mild conditions. A near-complete cellulose conversion to its monosaccharide could be realized at a relatively low enzyme loading of 20 FPU g(-1) glucan. The addition of water could suppress the condensation of lignin, yielding lignin with high purity (92.9%), a good fraction of beta-O-4 linkages reserved (24.8%) and homogeneous molecular weight (D < 2). Besides its highly digestible nature, the high quality of the cellulose-rich residue is also demonstrated from a material perspective. A more efficient fibrillation of obtained pulp to nanocellulose was developed, leading to a promising potential of energy saving compared to the traditional bleaching pathway. Overall, this work developed a mild pretreatment technology as a potential basis for a green and closed-loop biorefinery concept for converting lignocellulosic biomass to multiple products (high purity lignin, fermentable sugars, or functional materials).

Automated summary

This study reports the use of dimethyl isosorbide (DMI) as a solvent for fractionating lignocellulosic biomass into its main components. The pretreatment of Eucalyptus using DMI/H2O co-solvents achieves high lignin removal efficiency and good cellulose retention. The addition of water suppresses lignin condensation and produces lignin with high purity. Efficient fibrillation of obtained pulp leads to energy-saving potential.