Pretreatment of lignin-containing cellulose micro/nano-fibrils (LCMNF) from corncob residues

The explorations of valorizing crop wastes have drawn more and more attention in recent years. Among them, preparing lignin-containing cellulose micro/nano-fibrils (LCMNF) is an extremely promising strategy. In this study, LCMNF with a significant amount of lignin were prepared from corncob residues (CCR) left from xylose extraction. The focus of the work was to explore the influence of different pretreatment methods on the properties of LCMNF and the barrier properties of resulting films. The pretreatment methods included alkali-sulfite (AS), alkali-hydrogen peroxide (AP) and mediator-free laccase (ML), in which lignin was the pretreatment object. The results show that AS and AP increase the reactivity of lignin and cause the partial dissolution of lignin. In addition, the residual lignin does not affect the fibrillation of the CCR, but it reduces the water retention value of the resulting LCMNF, compared with lignin-free cellulose micro/nano-fibrils (DCMNF) from fully delignified CCR. As a result, the water contact angles of films from LCMNF are increased. Although different pretreatments have different effects on the barrier properties of films from LCMNF, the three preprocessing methods decrease the water vapor permeability (WVP) and oxygen permeability (OP). Especially for AS pretreatment, the film gives the lowest WVP (1.72 g mm/(m 2 day kPa), at 23 °C and 50%RH) and OP (0.85 (cm μm)/(m 2 ·24 h kpa), at 23 °C and 0% RH), which makes it promising for further application in packaging materials.