Impact of cationic polyelectrolyte on the nanoshear hybrid alkaline pretreatment of corn stover: Morphology and saccharification study

[Display omitted] ► The addition of polyelectrolyte in the pretreatment greatly modified the lignin in the biomass. ► It further induced the morphological changes of cell wall layers. ► Both glucose and xylose yields were enhanced in the enzymatic hydrolysis. ► Lignin migrated, redistributed, and formed globular complex. Cationic polyelectrolyte was first used as the additive in the nanoshear hybrid alkaline pretreatment of corn stover. The novel nanoshear hybrid pretreatment process was recently developed at MSU. The chemical compositions and morphologies were investigated by SEM, TEM, confocal CLSM, and XPS to elucidate the degradation mechanism of cellular structures. At room temperature and fast processing conditions (∼2min), lignin was found to redistribute on the inner and outer surfaces of the cell wall as lignin aggregate droplets instead of being extracted. Free microfibrils in the residues were also observed. The yields of enzymatic hydrolysis were enhanced for the pretreated corn stover with the aid of polyelectrolyte as an additive. We speculate that lignin was effectively modified which opened up the cell wall structure during the short pretreatment process and prevented non-productive binding of enzymes in the enzyme hydrolysis reaction.