4.2.2 1-Ethyl-3-Methylimidazolium Acetate (Emim-CH 3 COO)
Emim-CH 3 COO is an aprotic imidazolium and in-room temperature ionic liquid
normally reported due to its high solubility properties for biomass pretreatment. It is
helpful for in situ enzymatic saccharifications because of its biocompatibility and
enzymatic activity (André et al. 2013). High-purity cellulose and 52.7% of lignin
were obtained previously by pretreatment of wheat straw using Emim-CH 3 COO
(Zhu et al. 2017).
4.2.3 1-Butyl-3-Methylimidazolium Hydrogen Sulfate (Bmim-HSO 4 )
Acid-based ILs can catalyze hemicellulose, cellulose, or lignin. Bmim-HSO 4 was
reported as being capable of hydrolyzing and converting the hemicellulose fraction
of wheat straw without additional usage of catalyst (Bernardo et al. 2019). As a
consequence of the acidic property of the Bmim-HSO 4 , increased lignin content can
be observed in the regenerated material. This also helps to avoid lignin extraction to
the liquid stream and also promotes the hydrolysis process. The hydrolysis of wheat
straw using Bmim-HSO 4 at 140
C for 90 min resulted in 75% lignin release (André
et al. 2013).
4.2.4 1-Butyl-3-Methylimidazolium Thiocyanate (Bmim-SCN)
Bmim-SCN is the most studied IL as a result of its excellent solubility properties for
biomass pretreatment. The use of Bmim-SCN and Bmim-N(CN) 2 did not permit an
absolute dissolution of wheat straw, opposing to Bmim-HSO 4 with which a microscopic absolute dissolution was determined. Bmim-SCN when used for wheat straw
pretreatment, the purity of the fractionated sample, and the recovery in biomass can
be tuned, providing flexibility in the process. The usage of Bmim-SCN also helped
to obtain high-purity lignin. Bmim-SCN is a more competent IL for the residue
fractionation, as a larger quantity of each fraction (cellulose, hemicellulose, and
lignin-rich material) was recovered (André et al. 2013).
4.2.5 1-Ethyl-3-Methylimidazolium Diethyl Phosphate (EMIM-DEP)
EMIM-DEP is advantageous, as it is simple to be synthesized on a commercial scale
with high yield. Phosphate-based ILs are less viscous than the chloride type and are
more thermally stable than format ones. The yield of reducing sugars from wheat
straw pretreated with EMIM-DEP IL at 130
C for 30 min was 54.8% after being
enzymatically hydrolyzed for 12 h, and the glucose obtained was 2.51 mg/10 mg
regenerated wheat straw (Galbe and Wallberg 2019).
58
I. Neme and C. Masi
Emim-CH 3 COO is an aprotic imidazolium and in-room temperature ionic liquid
normally reported due to its high solubility properties for biomass pretreatment. It is
helpful for in situ enzymatic saccharifications because of its biocompatibility and
enzymatic activity (André et al. 2013). High-purity cellulose and 52.7% of lignin
were obtained previously by pretreatment of wheat straw using Emim-CH 3 COO
(Zhu et al. 2017).
4.2.3 1-Butyl-3-Methylimidazolium Hydrogen Sulfate (Bmim-HSO 4 )
Acid-based ILs can catalyze hemicellulose, cellulose, or lignin. Bmim-HSO 4 was
reported as being capable of hydrolyzing and converting the hemicellulose fraction
of wheat straw without additional usage of catalyst (Bernardo et al. 2019). As a
consequence of the acidic property of the Bmim-HSO 4 , increased lignin content can
be observed in the regenerated material. This also helps to avoid lignin extraction to
the liquid stream and also promotes the hydrolysis process. The hydrolysis of wheat
straw using Bmim-HSO 4 at 140
C for 90 min resulted in 75% lignin release (André
et al. 2013).
4.2.4 1-Butyl-3-Methylimidazolium Thiocyanate (Bmim-SCN)
Bmim-SCN is the most studied IL as a result of its excellent solubility properties for
biomass pretreatment. The use of Bmim-SCN and Bmim-N(CN) 2 did not permit an
absolute dissolution of wheat straw, opposing to Bmim-HSO 4 with which a microscopic absolute dissolution was determined. Bmim-SCN when used for wheat straw
pretreatment, the purity of the fractionated sample, and the recovery in biomass can
be tuned, providing flexibility in the process. The usage of Bmim-SCN also helped
to obtain high-purity lignin. Bmim-SCN is a more competent IL for the residue
fractionation, as a larger quantity of each fraction (cellulose, hemicellulose, and
lignin-rich material) was recovered (André et al. 2013).
4.2.5 1-Ethyl-3-Methylimidazolium Diethyl Phosphate (EMIM-DEP)
EMIM-DEP is advantageous, as it is simple to be synthesized on a commercial scale
with high yield. Phosphate-based ILs are less viscous than the chloride type and are
more thermally stable than format ones. The yield of reducing sugars from wheat
straw pretreated with EMIM-DEP IL at 130
C for 30 min was 54.8% after being
enzymatically hydrolyzed for 12 h, and the glucose obtained was 2.51 mg/10 mg
regenerated wheat straw (Galbe and Wallberg 2019).
58
I. Neme and C. Masi