pH pre-corrected liquid hot water pretreatment on corn stover with high hemicellulose recovery and low inhibitors formation

• An effective pH pre-corrected liquid hot water pretreatment process was developed.
• This pretreatment reduced the hemicellulose degradation by 35.3–92.3%.
• This pretreatment decreased furfural formation by 90.5–99.8%.
• The reserved hemicellulose did not hinder cellulose enzymatic hydrolysis.
• The pretreated and components reserved biomass make a good biorefinery feedstock.

A challenge for lignocellulosic pretreatment is how to retain hemicellulose as much as possible. To reduce the degradation of hemicellulose and increase the recovery of sugars, an effective pH pre-corrected liquid hot water pretreatment (LHWP) was developed by employing a small amount of NaOH (⩽5/100 g substrate) to accelerate the hemicellulose deacetylation and simultaneously pre-correct the acid hydrolyzate in situ. The results showed that the pH pre-correction can control the hydrolyzate pH. Under the pretreatment severity (PS) of 4.0, the pH pre-corrected LHWP reduced the hemicellulose degradation by 35.3–92.3%, decreased furfural formation by 90.5–99.8%. The highest hemicellulose recovery of 96.38% was obtained with pH pre-corrected by 2 g NaOH/100 g substrate. Enzymatic hydrolysis (EH) and simultaneous saccharification and fermentation (SSF) on the whole slurry from the pH pre-corrected LHWP showed that the hemicellulose retained in the solid residue did not bring significant resistance to cellulose EH (p = 0.837).