110th Anniversary: Distribution coefficients of furfural and 5-hydroxymethylfurfural in hydrophobic deep eutectic solvent + water systems: experiments and perturbed-chain statistical associating fluid theory predictions

Furfural (FF) and 5-hydroxymethylfurfural (HMF) are intermediates for many products, such as monomers for bioplastics, and can be obtained from various renewable resources. The isolation of these sugar-derived molecules from aqueous solutions is one of the main challenges in biorefinery processes. In the work described in this paper, the separation of FF and HMF from aqueous phases is carried out with hydrophobic deep eutectic solvents (DESs) as new extracting agents. Distribution coefficients of FF and HMF in 10 different hydrophobic DES + water systems have been measured and compared to that of the benchmark extracting agent (toluene). The dependence of the distribution coefficients on the presence of sugars in the system has also been investigated. The hydrophobic DESs were found to selectively extract FF and HMF from aqueous solutions without any co-extraction or precipitation of sugars. Finally, the distribution coefficients have been successfully predicted with PC-SAFT (perturbed-chain statistical associating fluid theory) without the need to fit any parameter to the measured distribution coefficients.