Utilization of Ionic Liquids in Lignocellulose Biorefineries as Agents for Separation, Derivatization, Fractionation, or Pretreatment

Abstract

Ionic liquids (ILs) can play multiple roles in lignocellulose biorefineries, including utilization as agents for the separation of selected compounds or as reaction media for processing lignocellulosic materials (LCM). Imidazolium-based ILs have been proposed for separating target components from LCM biorefinery streams, for example, the dehydration of ethanol-water mixtures or the extractive separation of biofuels (ethanol, butanol) or lactic acid from the respective fermentation broths. As in other industries, ILs are potentially suitable for removing volatile organic compounds or carbon dioxide from gaseous biorefinery effluents. On the other hand, cellulose dissolution in ILs allows homogeneous derivatization reactions to be carried out, opening new ways for product design or for improving the quality of the products. Imidazolium-based ILs are also suitable for processing native LCM, allowing the integral benefit of the feedstocks via separation of polysaccharides and lignin. Even strongly lignified materials can yield cellulose-enriched substrates highly susceptible to enzymatic hydrolysis upon ILs processing. Recent developments in enzymatic hydrolysis include the identification of ILs causing limited enzyme inhibition and the utilization of enzymes with improved performance in the presence of ILs.

Regenerated Lignocellulose Beads Prepared with Wheat Straw

“…Owing to their negligible vapor pressures and high thermal stability, they can be regarded as green solvents having many potential applications (Wasserscheid and Stark 2014). Some ILs dissolve lignocellulosic materials or their components (cellulose, hemicellulose, and lignin), which greatly promotes the utilization of lignocellulosic resources (Chowdhury et al 2014;Morais et al 2015;Peleteiro et al 2015;Silveira et al 2015). After dissolution in ILs, lignocellulosic materials can be converted into various products, such as furfural (Carvalho et al 2015), cellulosic aerogels , lignocellulosic aerogels (Li et al 2011), and modified regenerated bamboo that removes Cd 2+ and Pb 2+ (Zhong et al 2012).…”

An overview of the enzyme potential in bioenergy-producing biorefineries

“…Ionic liquids (ILs) are noteworthy substances that concern to biorefineries, considering that these may be used in biomass pretreatment, for cellulose hydrolysis and lignin removal, and in saccharification and bioproduct recovery . For instance, the imidazolium ILs have been used for separation of products such as ethanol, butanol and lactic acid due to their low vapor pressure, non‐flammability, thermal stability and good dissolution power.…”

“…For instance, the imidazolium ILs have been used for separation of products such as ethanol, butanol and lactic acid due to their low vapor pressure, non‐flammability, thermal stability and good dissolution power. Furthermore, ILs are potentially suitable for removing volatile organic compounds and carbon dioxide from gaseous biorefinery effluents . ILs are also suitable for separation of polysaccharides and lignin.…”

“…Recently, important developments in enzymatic hydrolysis include the identification of ILs causing enzyme inhibition and the use of enzymes with improved performance in the presence of ILs . The impairing of cellulases in high concentrations of ILs is likely due to their denaturalization as a consequence of higher viscosity and higher ionic strength in the medium, leading to the collapsing of catalytic sites .…”

Effect of Hydrolysis Treatment on Cellulose Nanowhiskers from Oil Palm (Elaeis guineesis) Fronds: Morphology, Chemical, Crystallinity, and Thermal Characteristics

“…Challenges posed by dwindling availability of non-renewable fossil resources such as petrochemical-based non-biodegradable plastics has contributed to the search for alternative polymer materials that are environmentally friendly and recyclable (Khan et al 2009;Peleteiro et al 2015). Polymeric composites are widely used due to their enhanced characteristics over plain polymer-based materials (Aprilia et al 2015).…”