Understanding the Effect of the Complex of Lignosulfonate and Cetyltrimethylammonium Bromide on the Enzymatic Digestibility of Cellulose

Lignosulfonate (LS) had various influences on the enzymatic digestibility of lignocelluloses for the complicated structure of LS. The effect of the complex of LS and cationic surfactant cetyltrimethylammonium bromide (LS–CTAB) on the enzymatic digestibility of corn stover and Avicel was investigated in this study. The LS–CTAB catanionic surfactant could significantly improve the enzymatic digestibility of Avicel and corn stover from 42.1 and 24.3% to 62.3 and 56.2%, respectively. In addition, the effect of LS–CTAB with various molecular weights and sulfonation degrees of LS and varied alkyl chain lengths of CnTAB on the enzymatic digestibility of Avicel was further investigated to reveal that the mechanism of LS–CTAB enhanced the enzymatic digestibility of cellulose. LS adsorbed on cellulase aggregates and dispersed the aggregates to form the smaller and more hydrophilic LS–cellulase aggregates. CTAB neutralized the electronegative charge of LS–cellulase aggregates, improved the interaction between cellulase and cellulose, and enhanced the enzymatic digestibility of cellulose.