An optimum combined hydrolysis factor enhances hybrid Pennisetum pretreatment in bio-conversion

Abstract

It is important to limit the formation of inhibitors when bio-refining lignocellulose for bioethanol production by steam explosion pretreatment. In this research, we found steam explosion with sulfite (SES) was an effective and efficient pretreatment for hybrid Pennisetum which was crossed by Pennisetum americanum and P.purpureum (Pennisetum americanum × P.purpureum) bio-conversion. The combined hydrolysis factor (CHF) derived from the kinetic models of hemicellulose hydrolysis and inhibitors formation was a useful indicator of pretreatment severity for a steam explosion with sulfite (SES) pretreatment. The apparent activation energy of hybrid Pennisetum pretreated by SES fitting with CHF (CHFses) was ~ 90 kJ/mol. CHFses can be used as predicting hemicellulose dissolution and substrate enzymatic digestion (SED), as well as balancing the trade-off between xylan remaining (XRses) and inhibitor formation. The correlation between CHFses and XRses was XRses = 0.78e−CHFses + 0.22e−0.282CHFses, and the relationship between XRses and SED was SED = $$28 + 221e^{{-X}_{R}ses/0.04}$$ . The xylan removal can reach up to 90% under mild conditions (temperature, pressure, and so on.) and was linearly related to enzymatic hydrolysis. CHFses determined in this study were effective in the experimental design of pretreatment for bioconversion of hybrid Pennisetum.