Induction of lignin solubility for a series of polar ionic liquids by the addition of a small amount of water

Abstract

Addition of a small amount of water was found to induce the lignin solubilizing ability in several polar ionic liquids which showed no lignin solubility in the absence of water. Similarly, addition of water was found to enhance lignin solubility in many polar ionic liquids. Though addition of water lowered the proton accepting ability of these ionic liquids, their proton donating ability was found to increase. The lignin dissolution by ionic liquids was newly found to be a function of both the proton accepting ability and proton donating ability of the ionic liquids. Water is a poor solvent for polysaccharides, and water addition has therefore been confirmed to be effective to improve the selective extraction yield of lignin from cedar powder under mild conditions

Metal‐Free Photochemical Degradation of Lignin‐Derived Aryl Ethers and Lignin by Autologous Radicals through Ionic Liquid Induction

“…ILs are an important type of highly efficient designable media with attractive properties such as high chemical stability and high solubility of substrates, [17] and have shown great practical applicationi n lignin upgrading, acting not only as an ideal solvent [18] but also as ac atalystf or bond cleavage. ILs are an important type of highly efficient designable media with attractive properties such as high chemical stability and high solubility of substrates, [17] and have shown great practical applicationi n lignin upgrading, acting not only as an ideal solvent [18] but also as ac atalystf or bond cleavage.…”

“…Recently,t he use of ionic liquids (ILs) has provided ap romising alternative to meet these requirements. ILs are an important type of highly efficient designable media with attractive properties such as high chemical stability and high solubility of substrates, [17] and have shown great practical applicationi n lignin upgrading, acting not only as an ideal solvent [18] but also as ac atalystf or bond cleavage. [19] In particular,d esignable ILs have been exploitedt op romote free-radical generation and demonstrate considerable potential for metal-free lignin degradation.F or example, ILs containing the anion bis[(trifluoromethyl)sulfonyl] imide ([NTf 2 ] À )w ith strong electronegativity could contributet ot he delocalization of electron pairs, which facilitatet he formation of COOH and thereby promote lignin transformation,p roducing the desired products in encouraging yields.…”

Natural Polymers from Biomass Resources as Feedstocks for Thermoplastic Materials

“…The described examples using tall oil or paraffin wax in PEG 200 plasticized lignin showed melting point reductions from initially 162 °C to ≈50 and 70 °C. [116] Following the previously described approach for cellulosics and also being a solvent for lignin, DES [123] and ILs [124,125] could additionally serve as potential external plasticizers. Sulfonamides, another group of plasticizers mainly used in hot-melt adhesives, could also benefit miscibility and favor plasticization based on structural similarities to lignin.…”

“…Following the previously described approach for cellulosics and also being a solvent for lignin, DES and ILs could additionally serve as potential external plasticizers. Sulfonamides, another group of plasticizers mainly used in hot‐melt adhesives, could also benefit miscibility and favor plasticization based on structural similarities to lignin.…”

Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

“…Although the complete dissolution of the whole biomass has been tested [137,138], the selective dissolution of its components has been more frequently proposed. Several ILs have demonstrated their effectiveness for lignin dissolution [139], but imidazolium-based ILs appear as the most representative examples [140][141][142][143][144][145][146][147][148][149]. As lignin can be selectively extracted from lignocellulosic biomass by employment of ILs, new simpler pretreatment methods can be developed for lignin isolation and purification [150,151].…”