Deep Eutectic Solvents for Pretreatment, Extraction, and Catalysis of Biomass and Food Waste

Abstract

Valorization of lignocellulosic biomass and food residues to obtain valuable chemicals is essential to the establishment of a sustainable and biobased economy in the modern world. The latest and greenest generation of ionic liquids (ILs) are deep eutectic solvents (DESs) and natural deep eutectic solvents (NADESs); these have shown great promise for various applications and have attracted considerable attention from researchers who seek versatile solvents with pretreatment, extraction, and catalysis capabilities in biomass- and biowaste-to-bioenergy conversion processes. The present work aimed to review the use of DESs and NADESs in the valorization of biomass and biowaste as pretreatment or extraction solvents or catalysis agents.

Deep Eutectic Solvent-Based Microextraction of Lead(II) Traces from Water and Aqueous Extracts before FAAS Measurements

“…Deep eutectic solvents are promising for the attraction of heavy metals from aqueous solutions because they are entirely composed of nitrogen and oxygen in their structure, in addition to the main skeleton of organic derived materials including carbon and hydrogen [ 34 , 35 ]. The separation and extraction of heavy metal ions from a sample solution depends on the pH of the medium due to the complexation between metal ions and the ligand [ 23 , 43 ].…”

“…Shah et al [ 33 ] developed an in-syringe system using ionic liquid for microextraction of Pb(II) with an LOD of 0.281 μg L −1 . Recently, a deep eutectic solvent was applied for microextraction as green solvents; it was composed of the coordination of hydrogen bond donors, such as long-chain carboxylic acids with hydrogen bond acceptors, such as quaternary ammonium salts or choline chloride, which reduce the melting point of the mixture, forming an organic viscus solution that is used to assess the separation of the aqueous and organic phases during microextraction procedures [ 34 , 35 , 36 , 37 , 38 ]. For example, Abolghasemi et al [ 39 ] used microextraction procedures with a deep eutectic solvent for the preconcentration of pesticides from food.…”

Biocatalyzed Redox Processes Employing Green Reaction Media

“…Two final aspects need to be consider when employing NADES as cosolvents in redox biocatalyzed processes. First, NADES are good solvents with several applications in extraction processes [ 98 , 99 , 100 ], so sometimes the recovery of the final product from the reaction medium can present some issues, a question to be taken into account for process designing. Finally, NADES can be recycled from the reaction media and used for several times, another aspect to consider.…”

Heterogeneous Catalysis with the Participation of Ionic Liquids

“…An example of the structural evolution of particular generations of ionic liquids is presented in Figure 2. An intensive development can be observed among ionic liquids themselves, as well as among the compounds that are not altogether regarded as ionic liquids such as deep eutectic solvents [35][36][37] or solvate ionic liquids [38]. Currently, the diversity of the application directions is very large, beginning from separation techniques [39] through the production and storage of energy [40,41], different types of biotransformations [42,43], organocatalysis [44], and ending with pharmaceuticals [45] and space technology [46].…”