Rheological characterization of ball-milled corn stover with different fragmentation scales at high-solids loading

A fundamental understanding of the rheology of high-solids lignocellulose slurry is essential for the design of efficient cellulosic ethanol production processes and bioreactors. Here we analyzed the rheological properties of high-solids corn stover slurries with particles size ranged from tissue scale to cellular scale. Results showed that the apparent viscosity/yield stress decreased with the increase of free water amount and the decrease of particle size, and the quantitative relationships among them were obtained. A 300-fold and 130-fold decrease in apparent viscosity and yield stress (30 % solids loading) were observed when the corn stover was reduced to cellular scale (<= 50 mu m). Further analysis revealed that size reduction to tissue scale reduces the viscosity and yield stress by alleviating the interactions between particles, while size reduction to cellular scale not only weakens the particle interactions, but also increases free water amount due to destruction of cell lumen, thus greatly enhances the rheological behaviors. And this improvement is undoubtedly of great significance for inter-unit operation and mixing energy saving.