Electrodialysis-assisted ionic liquid recovery with hydrogen production in biomass processing

The efficient recovery of ionic liquids is crucial for the sustainable conversion of biomass using ionic liquids. Electrodialysis has been demonstrated as an effective method for ionic liquid recovery through the selective transfer of target ions. The potential for simultaneous hydrogen (H2) production can be integrated into electrodialysis operations, owing to the reduction reaction occurring at the cathode. Therefore, the feasibility of electrodialysis for concurrent recovery of the ionic liquid 1-butyl-3-methylimidazolium chloride (BmimCl) and H2 production following sugarcane bagasse pretreatment was evaluated using a commercial electrodialysis module. The process relied on the enrichment of Bmim+ and Cl− ions coupled with the hydrogen evolution reaction (HER) involving H+. Under optimized conditions, the maximum BmimCl recovery ratio reached 99.2 %, with a specific energy consumption of 7.278 mol/kW·h. The H2 production rate and Faraday efficiency achieved 402.1 mmol/(m2·min) and 97.3 %. Both the reusability of electrodialysis system and the recycling performance of regenerated BmimCl were validated over five consecutive cycles. The estimated recovery cost of BmimCl ranged within 0.019–0.453 $/mol. This study present a novel approach for simultaneous ionic liquid recovery and H2 production after biomass processing, which enhanced the sustainability of ionic liquid-based biorefinery and offered new perspectives for green hydrogen production.