Use of Ionic Liquids and Deep Eutectic Solvents in Polysaccharides Dissolution and Extraction Processes towards Sustainable Biomass Valorization

Abstract

A shift to a bioeconomy development model has been evolving, conducting the scientific community to investigate new ways of producing chemicals, materials and fuels from renewable resources, i.e., biomass. Specifically, technologies that provide high performance and maximal use of biomass feedstocks into commodities with reduced environmental impact have been highly pursued. A key example comprises the extraction and/or dissolution of polysaccharides, one of the most abundant fractions of biomass, which still need to be improved regarding these processes’ efficiency and selectivity parameters. In this context, the use of alternative solvents and the application of less energy-intensive processes in the extraction of polysaccharides might play an important role to reach higher efficiency and sustainability in biomass valorization. This review debates the latest achievements in sustainable processes for the extraction of polysaccharides from a myriad of biomass resources, including lignocellulosic materials and food residues. Particularly, the ability of ionic liquids (ILs) and deep eutectic solvents (DESs) to dissolve and extract the most abundant polysaccharides from natural sources, namely cellulose, chitin, starch, hemicelluloses and pectins, is scrutinized and the efficiencies between solvents are compared. The interaction mechanisms between solvent and polysaccharide are described, paving the way for the design of selective extraction processes. A detailed discussion of the work developed for each polysaccharide as well as the innovation degree and the development stage of dissolution and extraction technologies is presented. Their advantages and disadvantages are also identified, and possible synergies by integrating microwave- and ultrasound-assisted extraction (MAE and UAE) or a combination of both (UMAE) are briefly described. Overall, this review provides key information towards the design of more efficient, selective and sustainable extraction and dissolution processes of polysaccharides from biomass.

pH-Responsive Nanostructures Based on Surface Active Fatty Acid-Protic Ionic Liquids for Imiquimod Delivery in Skin Cancer Topical Therapy

“…By careful selection of the constituting ions, the features of interest of an IL can be tailored to a given application. The range of potential applications of ILs span from alternative solvents for organic reactions [ 29 ] to dissolution media for biopolymers [ 30 ], and from lubricants [ 31 ] to electrolyte for batteries [ 32 ], to mention a few. Undeniably, in the last few years, the biomedical and pharmaceutical industry has turned increasing attention towards ILs due to their yet unexplored potential as bioactive agents or to their ability to solubilize and stabilize drugs [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ].…”

Deep Eutectic Solvents for the Valorisation of Lignocellulosic Biomasses towards Fine Chemicals

“…Several methods were investigated, such as hot water [6], supercritical fluid (sCO2) [14,15] and ionic liquid (IL) [16,17], and combined pretreatment methods [18][19][20] have been developed to optimize the performances and the processing costs. To avoid using non-ecofriendly chemical products (such as ILs [21][22][23][24][25][26]) in biomass Purified LCC fragments were isolated (using mannanase and a polyvinyl gel affine to lignin) and analysed (HMBC and 13 C-edited TOCSY-HSQC analyses). An α ether bond between the C-6 position of the β-mannose and the α position of lignin was detected through a correlation signal.…”

“…Several methods were investigated, such as hot water [6], supercritical fluid (sCO 2 ) [14,15] and ionic liquid (IL) [16,17], and combined pretreatment methods [18][19][20] have been developed to optimize the performances and the processing costs. To avoid using non-ecofriendly chemical products (such as ILs [21][22][23][24][25][26]) in biomass enhancement processes, in recent years, new, more environmentally friendly solvents have been more extensively used: deep eutectic solvents (DES).…”

Sugar-Based Ionic Liquids: Multifaceted Challenges and Intriguing Potential

“…These unique features made ILs the prototypical “designer solvents” [ 2 ] or “designable” molecules. The potential applications of ILs have been studied in a number of constantly growing and diverse areas of research, which include, but are not limited to, solvent systems or catalysts for organic reactions [ 3 ], electrolytes for batteries [ 4 ], biomasses dissolution, fractionation and modification [ 5 ], new IL-active pharmaceutical ingredients and drug delivery systems [ 6 ].…”