Ionic liquids for separation of lignin and transformation into value-added chemicals

Lignin-Based Covalent Adaptable Network Polymers─When Bio-Based Thermosets Meet Recyclable by Design

“…However, other attractive alternatives have also been proposed, such as the use of neoteric solvents like ionic liquids (ILs) and deep eutectic solvents (DES). These have been used for lignin isolation due to their low vapor pressure, high thermal and chemical stability, high solvation capacity, low melting point, tailor-made characteristics as well as greener and recyclable character. , The benefit of using ILs is represented by the effective fractionation of various biomass components with high purity owing to selective dissolution of carbohydrates or lignin fractions. − Depending on the IL used as well as the biomass, IL is able to solubilize up to ∼50 wt % of the lignin and allows for the extraction of up to ∼97 wt % of the lignin present in the lignocellulosic biomass . Similarly, lignin yields and purity obtained by using DES ranged from 15 to 95% and 94%, respectively .…”

“…Similarly, lignin yields and purity obtained by using DES ranged from 15 to 95% and 94%, respectively . In addition to pure lignin isolation in high yields, − both ILs and DES have also shown outstanding performance in lignin depolymerization. ,− Over the past decade, many greener and more sustainable approaches have been developed for lignocellulose treatment; however, more research is still needed to put them along with the four lignins in Table .…”

Bio-based platform chemicals synthesized from lignin biorefinery

“…Ionic liquids, consisting of anions and cations, have drawn extensive attention in terms of lignin extraction because of their superior capacity for the destruction of the lignocellulosic structure, recyclable and environmentally friendly. [62][63][64] These anions and cations can selectively destroy lignocellulosic structures. According to the discrepancy in ionic liquid selectivity, lignin extraction from biomass by ionic liquid was divided into two cases: i.e., ionic dissolution and ionosolv pulping.…”

Spatio-Temporal Modification of Lignin Biosynthesis in Plants: A Promising Strategy for Lignocellulose Improvement and Lignin Valorization

“…This requires further research to develop strategies for isolating lignin from biomass using organic solvents, ionic liquids (ILs), and deep eutectic solvents (DESs) alone or in combination with thermo, mechanical and microwave-assisted methods (Zhou et al, 2022). The application of ILs for lignin fractionation from biomass has been gaining significant attention due to its nonvolatility, low melting temperatures, thermostability, ecofriendly nature, less impact on cellulose, and shorter reaction time (Rawat et al, 2022). ILs solubilize lignin from biomass by forming hydrogen bonds, covalent bonds, and pi stacking interactions (Singh, 2022), which has been reported as the ionoSolv process.…”

“…For example, lignin isolated from Eucalyptus nitens wood using ILs such as 1-butyl-3-methylimidazolium hydrogen sulfate or triethylammonium hydrogen sulfate has less recalcitrance for further downstream processing (Penin et al, 2020). It is worth mentioning that ILs can depolymerize different types of lignin into valuable chemicals like vanillin, eugenol, guaiacol, diethyl maleate, phenol, and others, with high conversion rates and selectivity (Rawat et al, 2022). In addition, lignin can be selectively removed from biomass in its native form in high purity using pyridinium formate based protic ionic liquids (PILs) at 75 °C (Hasanov et al, 2022).…”