Purification process coupling membrane filtration and adsorption for deep eutectic solvent (DES) recycling after...

Area of Science:

• Biomass Conversion and Biorefining
• Green Chemistry and Sustainable Processes
• Separation Science and Technology

Background:

• Deep eutectic solvents (DES) offer a sustainable alternative for lignocellulose fractionation due to their eco-friendly properties.
• Industrial application of DES is hindered by solvent loss and performance degradation caused by accumulated impurities from repeated cycles.
• Effective DES purification is crucial for economic viability and environmental sustainability in lignocellulosic biorefineries.

Purpose of the Study:

• To develop and evaluate an integrated purification strategy for recycling DES used in lignocellulose fractionation.
• To address the challenges of impurity accumulation and solvent performance loss in repeated DES extraction cycles.
• To demonstrate the feasibility of a hybrid membrane-adsorption process for efficient DES recovery and reuse.

Main Methods:

• An integrated purification process combining ultrafiltration, continuous adsorption, and nanofiltration was designed.
• Membrane filtration (UF/NF) and adsorption resins were selected and tested for their efficacy in removing lignin degradation products and hemicellulose fragments.
• The performance of the integrated system was evaluated based on DES purification efficiency, impurity removal rates, and recovery of purified DES.

Main Results:

• The hybrid process effectively removed lignin degradation products (approx. 50% by adsorption) and concentrated hemicelluloses (approx. 70% by nanofiltration).
• Purified recycled DES demonstrated significantly restored lignin extraction yields (approx. 90%), comparable to fresh DES (approx. 70%).
• Untreated recycled DES showed drastically altered fractionation performance (approx. 150% modification), emphasizing the impact of impurity buildup.

Conclusions:

• Hybrid membrane-adsorption processing offers a robust and practical solution for purifying and recycling DES in lignocellulosic biorefineries.
• This approach facilitates cleaner solvent cycles, reduces DES consumption, and enhances the overall environmental and economic performance of biorefining processes.
• The developed purification strategy holds potential for further optimization and scale-up, paving the way for wider industrial adoption of DES technology.