Sodium hydroxide regeneration of trialkylamine extractant containing inhibitors from corn stover prehydrolyzate by liquid–liquid extraction

• NaOH was very suitable to back extraction regeneration of the extractant.
• NaOH could remove 100% acetic acid from the extractant.
• The regenerated extractant reused ten cycles had no problem.

Trialkylamine was an effective extractant for the removal of inhibitors from corn stover prehydrolyzate. Ethanol fermentability of the extracted prehydrolyzate was improved significantly. An approach for regeneration and valuable solutes (mainly acetic acid) recovery from such extractant was to back-extract the extractant containing inhibitors with sodium hydroxide. The influences of NaOH concentration, aqueous–organic phase ratio (A/O) on the extractant regeneration were investigated. The results indicated that 17.5 g/l NaOH could remove 100% acetic acid at A/O of 1:1. 175 g/l NaOH at A/O of 1:10 could also reach the same effect. Likewise, the results of 175 g/l NaOH at A/O of 1:1 repeatedly back-extracted the extractant for ten cycles were the same as before. The performance of regenerated extractant on extraction the corn stover prehydrolyzate showed almost no change after reused ten cycles. So NaOH was very suitable to regenerate the extractant containing inhibitors in bioethanol industry.