Screening ionic liquids for dissolving hemicellulose by COSMO-RS based on the selective model.

Area of Science:

• Biomass Valorization
• Computational Chemistry
• Green Chemistry

Background:

• Growing interest in renewable biomass resources due to depletion of non-renewable resources.
• Hemicellulose, a major biomass component, remains less studied compared to cellulose and lignin.
• Ionic liquids (ILs) show promise for lignocellulosic pretreatment, but efficient solvent screening is challenging.

Purpose of the Study:

• To develop accurate computational models for predicting ionic liquid (IL) solvent efficacy for hemicellulose dissolution.
• To screen a large library of ILs for their potential to dissolve hemicellulose.
• To elucidate the thermodynamic principles governing hemicellulose-IL interactions.

Main Methods:

• Construction and validation of six hemicellulose models, identifying the mid-dimer of the xylan chain hemicellulose (MDXC) model as most suitable.
• Screening of 1368 ILs using the Conductor-like Screening Model for Real Solvents (COSMO-RS) based on the MDXC model.
• Analysis of activity coefficient (γ), excess enthalpy (H^E), and σ-profile to understand solvent-IL interactions.

Main Results:

• The MDXC model demonstrated high accuracy in predicting hemicellulose dissolution behavior.
• COSMO-RS screening identified key interactions, highlighting the crucial role of hydrogen bonding in hemicellulose dissolution.
• Anions, particularly small ones with hydrogen-bond acceptor groups, were found to be more critical than cations in enhancing IL efficacy.

Conclusions:

• The study provides a thermodynamic understanding of hemicellulose-IL solvent systems.
• Accurate solute modeling is essential for reliable prediction of IL performance in biomass dissolution.
• This approach facilitates the discovery of efficient and sustainable ionic liquids for biomass processing.