Rheology of pumpable slurry of enzymatic hydrolysis lignin in fuel compatible solvent with high solid loading

Enzymatic hydrolysis lignin (EHL) is the main solid waste from the growing second-generation (2G) bioethanol production industry. The industrial valorization of EHL with large scale requires a highly efficient transportation method. Slurries composed of solid and liquid phases have been widely employed in the pipeline transportation of solid feedstocks. In this work, two types of EHL samples, i.e., corn cob EHL (CC EHL) and pine wood EHL (PW EHL), were utilized to prepare EHL-alkane and EHL-alcohol slurries. Among the slurries examined, the CC EHL-alkane slurry exhibits the highest flowable solid concentration, achieving 70 wt%. The CC EHL-alcohol slurry shows dilatant characteristics, while CC EHL-alkane, PW EHL-alcohol, and PW EHL-alkane slurries present pseudoplasticity. The increase of particle size results in the decrease of the viscosity of the CC EHL-heptane slurry. The CC EHL-alkane slurries and all PW EHL slurries with highest solid concentration display pumpability and possibility of pipeline transportation. The dispersants, i.e., Span 80 and oleic acid, significantly improve the stability of EHL-heptane slurry.