for high-value paper products; biological methods require an extensive residence
time; the physical and irradiation pretreatments are power demanding and do not
eliminate the lignin; hot water and steam explosion pretreatment methods are
measured as very positive; however, they need a high amount of pressure/temperature and use of catalyst. A researcher discovered that new and nonvolatile solvents
called ionic liquids (ILs) were able to dissolve large amounts of lignocellulosic
materials (Reddy 2015; Guan et al. 2018). Generally, ionic liquids are defined as
salts with a low melting point and possess an organic cation and inorganic anion
(Galbe and Wallberg 2019). Ionic liquids (ILs) are the potential solvents for the
pretreatment of lignocelluloses materials as they are thermally constant, are
eco-friendly, and have low volatility. Ionic liquids have the potential to dissolve
biomass by effectively disrupting the dynamic network of non-covalent
carbohydrate-lignin interactions (Yang et al. 2011). Nowadays, the usage of ionic
liquids in the extraction of carbohydrates from the lignocellulosic materials is
studied extensively (André et al. 2013). This review article compares the extractive
capacity of various types of ionic liquids, discussing the most favorable situation for
the pretreatment of wheat straw residue separately for bioethanol production.
2 Availability of Wheat Straw
Wheat straw is considered as a potential feedstock for ethanol production. Europe,
East Asia (i.e., China, India), the United States of America, and Canada are the most
wheat producers in the world. Globally, around 850 million metric tons of wheat
straw per annum is produced, which can be considered as a big farming residue.
Wheat straw can produce about 120 billion liters of bioethanol per annum, which can
substitute 93 billion liters of gasoline (Fu and Mazza 2011). Ethiopia is the top fourth
cereal-producing country in Africa. Wheat, maize, teff, sorghum, and barley are the
main cereal crops, covering more than 80% of the croplands (André et. al.
2013; Tucho and Nonhebel 2015). The annual yields of crops directly determine
their corresponding quantity of residues. Wheat straw is one of the most abundant
lignocellulosic crop residues in Ethiopia. Its annual production is about 2.1 tons per
hectare crop yield, and its residue is 2.7 tons per hectare annually (Wei et al.
2012; Tucho and Nonhebel 2015). Losing this huge quantity of residues for a
country, like Ethiopia, is an enormous energy/fuel loss.
2.1 Potential and Properties of Wheat Straw as a Precursor
for Bioethanol Production
Wheat straw is one of the lignocellulosic biomass, constituting of 33%–40% cellulose, 20%–25% hemicelluloses, and 15%–20% lignin. Figure 3.1 provides a general
52
I. Neme and C. Masi
time; the physical and irradiation pretreatments are power demanding and do not
eliminate the lignin; hot water and steam explosion pretreatment methods are
measured as very positive; however, they need a high amount of pressure/temperature and use of catalyst. A researcher discovered that new and nonvolatile solvents
called ionic liquids (ILs) were able to dissolve large amounts of lignocellulosic
materials (Reddy 2015; Guan et al. 2018). Generally, ionic liquids are defined as
salts with a low melting point and possess an organic cation and inorganic anion
(Galbe and Wallberg 2019). Ionic liquids (ILs) are the potential solvents for the
pretreatment of lignocelluloses materials as they are thermally constant, are
eco-friendly, and have low volatility. Ionic liquids have the potential to dissolve
biomass by effectively disrupting the dynamic network of non-covalent
carbohydrate-lignin interactions (Yang et al. 2011). Nowadays, the usage of ionic
liquids in the extraction of carbohydrates from the lignocellulosic materials is
studied extensively (André et al. 2013). This review article compares the extractive
capacity of various types of ionic liquids, discussing the most favorable situation for
the pretreatment of wheat straw residue separately for bioethanol production.
2 Availability of Wheat Straw
Wheat straw is considered as a potential feedstock for ethanol production. Europe,
East Asia (i.e., China, India), the United States of America, and Canada are the most
wheat producers in the world. Globally, around 850 million metric tons of wheat
straw per annum is produced, which can be considered as a big farming residue.
Wheat straw can produce about 120 billion liters of bioethanol per annum, which can
substitute 93 billion liters of gasoline (Fu and Mazza 2011). Ethiopia is the top fourth
cereal-producing country in Africa. Wheat, maize, teff, sorghum, and barley are the
main cereal crops, covering more than 80% of the croplands (André et. al.
2013; Tucho and Nonhebel 2015). The annual yields of crops directly determine
their corresponding quantity of residues. Wheat straw is one of the most abundant
lignocellulosic crop residues in Ethiopia. Its annual production is about 2.1 tons per
hectare crop yield, and its residue is 2.7 tons per hectare annually (Wei et al.
2012; Tucho and Nonhebel 2015). Losing this huge quantity of residues for a
country, like Ethiopia, is an enormous energy/fuel loss.
2.1 Potential and Properties of Wheat Straw as a Precursor
for Bioethanol Production
Wheat straw is one of the lignocellulosic biomass, constituting of 33%–40% cellulose, 20%–25% hemicelluloses, and 15%–20% lignin. Figure 3.1 provides a general
52
I. Neme and C. Masi