Tissue fractionation of corn stover through steam explosion-assisted mechanical carding: Its effect on enzymatic hydrolysis and pulping

The complication of bioconversion starts from corn stover's structural inhomogeneity resulting in low enzymatic hydrolysis and pulping efficiency. Contrarily, higher efficacy necessitates the homogeneity of raw material, which demands a better understanding of tissue and cell modules. The proposal "Tissue Fractionation through Steam Explosion-Assisted Mechanical Carding (SEME)" can effectively fractionate corn stover into vascular and parenchyma tissues without adding chemical and water, resulting in low pollution. The result showed that the enzymatic hydrolysis yield of parenchyma tissue fraction (PTF) was 1.33 and 1.16 times higher than that of vascular tissue fraction (VTF) and the whole steam-exploded corn stover, respectively. It also revealed that each part of corn stover, namely, pith, rind, and leaf, showed higher enzymatic hydrolysis performance 1.09, 1.77, and 1.37 times, respectively, in the case of PTF than that of VTF. By characterizing with Brunauer-Emmett-Teller low-field nuclear magnetic resonance and analyzing with multiple-factor regression, it was found that the higher yield of enzymatic hydrolysis was attributed to the homogeneity improvement of interface properties instead of cellulose content. Furthermore, with the ethanol self-catalyzed pulping method, VTF was used to prepare unbleached pulp whose strength properties fulfilled the indexes of grade A corrugated medium, and the yield reached up to 57.6%, which is 1.26 times higher than that of cornstalk. This study provides a new method of tissue fractionation to improve the degree of usability of total corn stover for enzymatic hydrolysis and pulping considering the cost competitiveness in the economical stage.