Effect of severity factor on the hydrothermal pretreatment of sugarcane straw

TLDR

Sugarcane straw’s recalcitrant lignocellulosic structure necessitates pretreatment, but energy use and inhibitor formation demand optimization. The study used a 2² factorial design with a central point to assess how severity factor (SF) influences hydrothermal (liquid hot water) pretreatment. Low SF (<3.39) produced little structural change, whereas high SF (>4.70) caused sugar loss, furfural and pseudo‑lignin formation despite ~97 % hemicellulose removal; residence time had little effect, and the optimal condition was 10 min at 195 °C, yielding 9.8 % cellulose solubilization and 85.45 % hemicellulose removal.

Abstract

The recalcitrant structures of sugarcane straw and related lignocellulosic biomasses require a pretreatment step to enable a better enzymatic attack during the hydrolysis. Factors like the energy consumption and the formation of inhibitors require the optimization of the pretreatment step. Thus, the influence of different severity factors (SF) on hydrothermal (also called liquid hot water, LHW) pretreatment was evaluated using a factorial design 22 with central point. The obtained results showed that low values of SF (<3.39) did not promote reasonable alteration in the sugarcane straw structures, whereas high SF values (>4.70) resulted in loss of hydrolyzed sugars, generation of inhibitors such as furfural, and formation of pseudo-lignin structures, despite high hemicellulose removal (∼97%). The residence time exhibited low influence on LHW. An optimum condition was found for the process (10 min and 195 °C) with low cellulose solubilization (9.80%) and a reasonable hemicellulose removal (85.45%).