Aromatics extraction from pyrolytic sugars using ionic liquid to enhance sugar fermentability.

Area of Science:

• Biotechnology and Biofuel Production
• Green Chemistry
• Biomass Valorization

Background:

• Pyrolytic sugars derived from lignocellulosic biomass are a promising feedstock for bioethanol production.
• Aromatic compounds present in pyrolytic sugars inhibit fermentation and reduce ethanol yield.
• Efficient methods for removing inhibitors are crucial for optimizing bioethanol production from biomass.

Purpose of the Study:

• To evaluate the effectiveness of liquid-liquid extraction using an ionic liquid (IL) and ethyl acetate (EA) for removing aromatic inhibitors from pyrolytic sugars.
• To assess the reusability of the ionic liquid for sustainable process design.
• To determine the impact of aromatics removal on fermentative bioethanol production yield.

Main Methods:

• Pyrolytic sugar solutions were prepared from untreated and acid-leached pinewood.
• Liquid-liquid extraction was performed using trihexyltetradecylphosphonium dicyanamide (P666,14[N(CN)2]) as the ionic liquid and ethyl acetate as a comparison solvent.
• The efficiency of aromatics removal and sugar recovery was quantified.
• The purified sugar fraction was hydrolyzed and fermented to produce bioethanol.
• Ionic liquid regeneration was achieved via vacuum evaporation.

Main Results:

• The ionic liquid P666,14[N(CN)2] removed 70% of aromatics, while ethyl acetate removed 50%, with no significant sugar loss.
• Regenerated ionic liquid demonstrated comparable aromatics extraction efficiency to fresh IL.
• Bioethanol fermentation of purified sugars from pretreated pinewood yielded 0.46g ethanol/(g glucose), approaching the theoretical maximum.

Conclusions:

• Liquid-liquid extraction with the ionic liquid P666,14[N(CN)2] is a highly effective method for removing inhibitors from pyrolytic sugars.
• The regenerability of the ionic liquid supports its application in sustainable and cost-effective bioethanol production.
• Improved feedstock purification significantly enhances fermentative bioethanol yields from biomass-derived sugars.