Use of Deep Eutectic Solvents in the Treatment of Agro-Industrial Lignocellulosic Wastes for Bioactive Compounds

Abstract

Lignocellulose is the most abundant component in nature since it refers to plant material. Beyond the enormous utilization of lignocellulose by human being, unignorable amount of waste is also formed simultaneously. Agro-industrial lignocellulosic wastes can cause environmental pollutions if not processed before discharged. An innovative approach for lowering the detrimental influences of lignocellulosic wastes is to consider them as a source of useful products rather than a waste to be decontaminated. Beyond the conventional techniques for evaluation of the wastes, new emerging techniques and the use of new solvents have drawn attention recently. Among new generation solvents, deep eutectic solvents (DESs) have been increasingly used in the treatment of lignocellulosics to produce value-added products such as biofuels, chemicals, and solvents and also used for the recovery of bioactive phenolic compounds. DESs are used extensively for fractionation of lignocellulosic wastes, often in combination with enzymatic hydrolysis of the biomass. On the other hand, extraction and recovery of bioactive compounds are also under research using DESs. This mini review summarizes the very recent literature reports on the use of DESs in treating agro-industrial wastes within the concept of valorization of biomass.

Recent advances in green solvents for lignocellulosic biomass pretreatment: Potential of choline chloride (ChCl) based solvents

“…The applications of DESs/LTTMs were also reported in fields of chemical and polymer synthesis, metal electrodeposition, nanomaterials, CO 2 capturing, biomass and biofuels processing, biomedicine, pharmaceutics, food processing, cosmetics, etc. (Ezgi Ünlü & Takaç, 2020;Marcus, 2019;Paiva et al, 2014;Silva et al, 2019). Some other applications of ChCl-based solvents include: i. Microalgal biomass pre-treatment for the extraction of cellular components by using ChCl/1,2-Propanediol/Water (Cicci et al, 2017).…”

Effect of lignin in cellulose nanofibers on biodegradation and seed germination

“…Choline chloride-urea as a natural deep eutectic solvent is commonly used for the dissolution and disruption of lignocellulose, reducing energy requirements to break lignin-lignin ether bonds and lignin-hemicellulose ester bonds [37][38][39]. The solvent causes fibers to swell and expand, allowing access for the succinic anhydride into the internal fiber structure [23,40].…”

“…4). The process reduces lignocellulose microfibers (LCMF) into lignocellulose nanofibers (LCNF) with diameters in the nanoscale [38]. The processing time in the lab is reduced from 1 to 2 h of direct ball milling [41][42][43] to 15 min, reducing the energy requirements by a factor of 4 to 8 using the deep eutectic solvent.…”