Novel Solvent Systems for Biomass Fractionation Based on Hydrogen‐Bond Interaction: A Minireview

Abstract

cellulose (30-50 wt%), hemicellulose (20-35 wt%), and lignin (15-30 wt%). [3] CO -C bonds are the main connection bond in the components, but between different components hydrogen bond is the main connection. [2b,4] Cellulose is the most abundant component composed by d-glucose units linked to each other via β-1,4-glycosidic bonds, a certain amount of cellulose shows ordered crystal structure. [5] Hemicellulose is composed with various polymerized monosaccharides, mainly are C5 (xylose, arabinose) and C6 sugars (mannose, glucose, and galactose), and others, which acts as a linkage distributing between cellulose and lignin. [6] Lignin is one kind of highly complicated cross-linked 3D amorphous resin, which is composed of three monolignols (p-coumaryl, alcohol, coniferyl alcohol, and sinapyl alcohol) connected by different CO -O bonds. [1a] Lignin mainly lies on the surface of cellulose and hemicellulose that ensures the structural integrity and rigidity of biomass. [3,7] Currently biomass catalytic conversion has achieved great success in breaking CO -C bond, so converting single component to platform chemicals or materials is quite close to industrialization. The key of efficient application of whole biomass becomes the separation of different components with high efficiency. Owing to the complex structure of biomass, biomass fractionation is the key process for the full and efficient utilization of this renewable resource. [8] In the previous reports, various solvent systems, such as strong dilute acid treatment, [9] alkaline treatment, [10] the sulphite pulping process, [11] and organosolv isolation, [12] were used to separate cellulose, hemicelluloses, lignin, and their derivatives. However, most of those traditional methods always cause serious environmental consequences and result in more cost in waste disposal owing to the application of large amounts of acids and bases. [13] By contrast, ionic liquids (ILs) [8a,b,14] and deep eutectic solvents (DESs) [4,15] are widely regarded as a green alternative solvent for their near-zero vapor pressure, high thermal stability, devisable structure, and excellent solvent power for biomass. [4b,8b,16] Not like acid or base pretreatment methods that need destruction and then fractionation of biomass components, ILs and DESs methods can achieve highly selective fractionation of biomass by controlling the functional structure of ILs or composition of DESs. [4b,8a,14b,16] According to the existing reports, many ILs and

Common Ivy (Hedera Helix L.) as a Novel Green Resource in an Urban Biorefinery Concept

“…114 Current research has been searching for novel sustainable solvents for biomass fractionation as an alternative for this alkaline treatment. 115 In this regard, natural deep-eutectic solvents (NADES) show promise as sustainable recyclable biomass fractionation agents as certain NADES can dissolve lignin and hemicellulose. 116 Only one study reported the treatment of CI with NADES, 65 specifically choline chloride/malic acid.…”

High-performance delignification of invasive tree species wood with ionic liquid and deep eutectic solvent for the production of cellulose-based polyelectrolytes

“…The determination of klason lignin and acid-soluble lignin contents was based on a two-step hydrolysis with sulfuric acid, and then, the resulting hydrolyzed products were used for carbohydrate content determination by high-performance liquid chromatography (HPLC), using a Knauer instrument equipped with a refractive index (RI) detector and a Rezex ROA-organic acid H column from Phenomenex. Aer these determinations, the removals of the main wood components (cellulose, xylan and lignin) obtained aer the pretreatments were calculated based on eqn (2).…”

“…Using this DES, higher delignication yields could be achieved with less wood dissolution, which means that The treated wood samples that showed a delignication yield higher than 60% (Fig. 3) were selected for carbohydrate content determinations, which enabled the calculation of cellulose and xylan removals by eqn (2). The detailed compositions of these treated woods and untreated wood, as well as the removals of the main wood components obtained aer the pretreatments, are presented in Table 1.…”

“…This type of biomaterial is mainly composed of cellulose (30-50%, w/w), hemicelluloses (20-35%) and lignin (15-30%) with smaller amounts of ash, extractives, pectin and proteins. 2,3 The strong hydrogen and covalent bonds between carbohydrates and lignin (lignin-carbohydrate complex) results in a complex, rigid and recalcitrant structure, which renders difficult the lignin removal/isolation and the fractionation of the lignocellulosic biomass into its several components. The access of hydrolyzing enzymes to produce fermentable sugars is also hindered.…”

“…9,10 Due to these unique properties, ILs are suitable for a wide range of applications being one of them the ability to dissolve simultaneously or selectively the main components of lignocellulosic biomass (cellulose, hemicelluloses and lignin). 2 Despite these attractive properties, ILs have high viscosity, poor biodegradability and high cost of production. However, it is possible to overcome these limitations since there are innumerous combinations of cations and anions that can be used in order to tailor the physicochemical properties of ILs for a specic application.…”