Challenging DESs and ILs in the valorization of food waste: a case study

Abstract

In this study, the efficacy of two of the best performing green solvents for the fractionation of lignocellulosic biomass, cholinium arginate (ChArg) as biobased ionic liquid (Bio-IL) and ChCl:lactic acid (ChCl:LA, 1:10) as natural deep eutectic solvent (NADES), was investigated and compared in the pretreatment of an agri-food industry waste, apple fibers (90°C for 1 h). For the sake of comparison, 1-butyl-3-methylimidazolium acetate (BMIM OAc) as one of the best IL able to dissolve cellulose was also used. After the pretreatment, two fractions were obtained in each case. The results gathered through FTIR and TG analyses of the two materials and the subsequent DNS assay performed after enzymatic treatment led to identify ChArg as the best medium to delignify and remove waxes, present on the starting apple fibers, thus producing a material substantially enriched in cellulose (CRM). Conversely, ChCl:LA did not provide satisfactorily results using these mild conditions, while BMIM OAc showed intermediate performance probably on account of the reduced crystallinity of cellulose after the dissolution-regeneration process. To corroborate the obtained data, FTIR and TG analyses were also performed on the residues collected after the enzymatic hydrolysis. At the end of the pretreatment, ChArg was also quantitatively recovered without significant alterations.

Sustainable valorization of cherry (Prunus avium L.) pomace waste via the combined use of (NA)DESs and bio-ILs

“…Finally, the importance of pectin in the food sector lies in its ability to form gel, 95,96 hence its presence should not influence the gelling process. Therefore, ChArg, a different bio-based ionic liquid able to selectively remove the lignin and hemicellulose from lignocellulosic material 41,42 was selected for the pretreatment step which led to two different fractions. The cellulose enriched material, CRM (35 wt% of dried biomass) was obtained via filtration as the undissolved material, while a fraction enriched in lignin and hemicellulose was precipitated from the filtrate acidifying the solution (22 wt% of dried biomass).…”

“…ChArg (Fig. 2) was synthesised as described previously by To et al 40,41 Briefly, prior to use, commercial choline hydroxide (ChOH) aqueous solution ( ca. 47–50%) was titrated with 1 M HCl solution giving the exact percent of ionic liquid in water (49.15%).…”

“…After polyphenol extraction, the undissolved residue was treated with ChArg following the procedure previously described by Hou et al , 44 An et al 42 and in our previous work 41,43 with some modifications. The treatment was performed under milder condition than those described by the authors.…”

“…ChArg (Fig. 2) was synthesised as described previously by To et al 40,41 Briefly, prior to use, ance with those reported in the literature. 42 Cholinium levulinate (ChLev).…”

Enzymatic Valorization of Lignocellulosic Biomass—The Influence of Deep Eutectic Solvents and Ionic Liquids on the Activity of Cellulolytic Enzymes

“…Traditional methods for chemical transformation of biomass include the application of mineral acids or alkaline solutions, which are considered hazardous and toxic. Due to this, according to the Sustainable Development Goals, as well as green chemistry principles, a rapidly growing trend of replacing these methods with more environmentally friendly methods (e.g., thermal processing, pyrolysis, application of ionic liquids (ILs), deep eutectic solvents (DESs), and/or biocatalysts) is being observed [3][4][5][6].…”