Biorefinery Lignosulfonates from Sulfite-Pretreated Softwoods as Dispersant for Graphite

Two biorefinery lignosulfonates (LSs), Ca-LS-DF and Na-LS-LP, were, respectively, isolated from pilot-scale sulfite-pretreated spent liquor of lodgepole pine and fermentation residue of Douglas-fir harvest forest residue. The molecular weights of Na-LS-LP and Ca-LS-DF were approximately 9 000 and 11 000 Da, respectively. The two LSs were applied as dispersant for graphite in aqueous suspensions. The dispersion stability was evaluated by a scanning electron microscope and Turbiscan Lab Expert. LS performance in modifying graphite was better than that of a commercial dispersant Reax-85A as indicated by the Turbiscan TSI values, zeta potential of suspension particles, and SEM imaging. The practical importance of this study lies in the fact that the pilot scale sulfite pretreatments that produced the two LSs also produced excellent bioethanol yields at high titer without detoxification and washing, suggesting the LSs are a true value-added coproduct forhigh yield biofuel production.