Cellulose Membranes in the Treatment of Spent Deep Eutectic Solvent Used in the Recovery of Lignin from Lignocellulosic Biomass

Abstract

Ultrafiltration was employed in the purification of spent Deep Eutectic Solvent (DES, a mixture of choline chloride and lactic acid, 1:10, respectively) used in the extraction of lignin from lignocellulosic biomass. The aim of this was to recover different lignin fractions and to purify spent solvent. The results revealed that the commercial regenerated cellulose membranes—RC70PP and Ultracel 5 kDa UF membranes—could be used in the treatment of the spent DES. The addition of cosolvent (ethanol) to the spent DES decreased solvent’s viscosity, which enabled filtration. With two-pass ultrafiltration process with 10 kDa and 5 kDa membranes about 95% of the dissolved polymeric compounds (lignin and hemicelluloses) were removed from the spent DES. The utilized membranes also showed the capability to fractionate polymeric compounds into two fractions—above and under 10,000 Da. Moreover, the 10 kDa cellulose-based membrane showed good stability during a continuous period of three weeks exposure to the solution of DES and ethanol. Its pure water permeability decreased only by 3%. The results presented here demonstrate the possibility to utilize cellulose membranes in the treatment of spent DES to purify the solvent and recover the interesting compounds.

Deep eutectic solvents for catalytic biodiesel production from liquid biomass and upgrading of solid biomass into 5-hydroxymethylfurfural

“…230,231 Currently, the recycling methods commonly used for DESs include evaporation/distillation, membrane separation technology, crystallization, liquid-liquid extraction, etc. 232,233 Separation and recovery of DESs by evaporation/distillation is an appropriate strategy for the low vapor pressure of DESs. In the study of Kleiner et al, ChCl : Gly DESs were used as a solvent to catalyze the synthesis of biodiesel by lipases, allowing the ethyl ester content to be increased from solvent-free 83.7 wt% to 95.2 wt%.…”

“…230,231 Currently, the recycling methods commonly used for DESs include evaporation/distillation, membrane separation technology, crystallization, liquid–liquid extraction, etc . 232,233…”

DES: their effect on lignin and recycling performance

“…Ultrafiltration is an efficient and cost-effective method for DES recovery. Ippolitov et al 59 used RC70PP commercial regenerated cellulose membranes and Ultracel 5 kDa UF membranes to recover solvents of different lignin fractions (DES, a mixture of choline chloride and lactic acid, respectively, 1 : 10), as shown in Fig. 6 .…”

“…Fig.6Two-pass ultrafiltration membrane process (DES composition: choline chloride : lactic acid = 1 : 10) 59. …”

Ultrafiltration-based diafiltration for post-delignification fractionation of lignin from a deep eutectic solvent comprised of lactic acid and choline chloride

“…Ultrafiltration (UF) is likely to be applicable to concentrate lignin from DES-based dark liquors. [28][29][30][31]. However the retentate in single stage membrane operations will always contain DES therefore further dilution with a diluting solvent is required to lower the DES concentration in the lignin-rich retentate in order to obtain as pure lignin as possible.…”