3 Impacts of Wheat Straw Pretreatment Using Ionic
Liquids on a Sustainable and Cleaner Environment
When we think of “sustainable energy,” the energy resource that regularly appears to
the mind is, naturally, biomass. As a potential energy source, biomass is moderately
plentiful (ranked third, next to oil and coal). Biomass to energy conversions is
possibly the most sustainable and is considerably cleaner than coal: for instance,
in biomass-derived energy, nitrogen compound (NO x ) and sulfur compound (SO x )
emissions are very low. An additional benefit of biomass is being agreeable to smallscale installations with the guarantee of energy accessibility and economic growth in
rural and developing areas. Accordingly, a biomass processing capacity must be able
to convert various feedstocks without major penalties in overall performance, sugar
yield, and fuel production. Ionic liquid pretreatments are less energy demanding,
easier to handle, and more environmentally friendlier than the other pretreatment
methods like chemical and physical methods (Zhao et al. 2009). Chemicals used for
pretreatment are generally toxic to the microbes and enzymes used in the downstream processing to complete the biomass conversion process; thus, these reaction
agents can only be used once, making it more expensive (Hu and Ragauskas 2012).
For instance, sulfuric acid used in biomass pretreatment is not cost-effective for
reuse; it should be removed and disposed of using strategies that produce huge
amounts of solid wastes or wastewater. Additionally, in some cases, this results in
improper sugar losses or additional energy requirement and greenhouse gas exhaustions like ammonia (Humbird et al. 2011). Physical pretreatment of biomass conversion to ethanol is very energy extensive and is highly polluted (Sikarwar et al.
2016). Ionic liquids have also been largely considered for green chemistry with
many emerging kinds of research being conducted in the usage of ILs as a matter of
important subject in Green Chemistry (Welton 2011). Another study tells us that the
ionic liquids are known for their low volatility than that of the conventional
pretreatment chemicals used, and this proves that these ILs can proceed with the
pretreatment of the biomass at atmospheric pressure at high temperature. ILs are also
non-odorous and are relatively safer liquor, which can be easily handled (Brandt
et al. 2013). ILs have attractive characteristics as a possible replacement for conventional solvents in the separation process (Gonfa et al. 2011). Ionic liquids have
gained new attention to chemists as a green solvent for various purposes. The
toxicity analysis of 1-alkyl-3-methylimidazolium chloride-based ionic liquids was
assessed using the nematode Caenorhabditis elegans. In this toxicity analysis, where
various concentrations of the selected IL were preceded, their result is interpreted as
to understand the LC 50 /mg mL
À1 , which is represented in Table 3.3. Thus, after the
exposure of IL to the nematode, the initial chemical exposure was not fatal to the
worm, as it survived the exposure; moreover, there was successful reproduction by
the nematode, stating that the IL has a very low impact on the environmental
sustainability, especially to that of the life present on the ground (Swatloski et al.
2004). A specific ionic liquid 1-ethyl-3-methylimidazolium acetate, or known as
EMIMAc, is considered as a nontoxic, noncorrosive, and also biodegradable ionic
3 Pretreatment of Wheat Straw Using Ionic Liquids for Bioethanol Production. . .
55
Liquids on a Sustainable and Cleaner Environment
When we think of “sustainable energy,” the energy resource that regularly appears to
the mind is, naturally, biomass. As a potential energy source, biomass is moderately
plentiful (ranked third, next to oil and coal). Biomass to energy conversions is
possibly the most sustainable and is considerably cleaner than coal: for instance,
in biomass-derived energy, nitrogen compound (NO x ) and sulfur compound (SO x )
emissions are very low. An additional benefit of biomass is being agreeable to smallscale installations with the guarantee of energy accessibility and economic growth in
rural and developing areas. Accordingly, a biomass processing capacity must be able
to convert various feedstocks without major penalties in overall performance, sugar
yield, and fuel production. Ionic liquid pretreatments are less energy demanding,
easier to handle, and more environmentally friendlier than the other pretreatment
methods like chemical and physical methods (Zhao et al. 2009). Chemicals used for
pretreatment are generally toxic to the microbes and enzymes used in the downstream processing to complete the biomass conversion process; thus, these reaction
agents can only be used once, making it more expensive (Hu and Ragauskas 2012).
For instance, sulfuric acid used in biomass pretreatment is not cost-effective for
reuse; it should be removed and disposed of using strategies that produce huge
amounts of solid wastes or wastewater. Additionally, in some cases, this results in
improper sugar losses or additional energy requirement and greenhouse gas exhaustions like ammonia (Humbird et al. 2011). Physical pretreatment of biomass conversion to ethanol is very energy extensive and is highly polluted (Sikarwar et al.
2016). Ionic liquids have also been largely considered for green chemistry with
many emerging kinds of research being conducted in the usage of ILs as a matter of
important subject in Green Chemistry (Welton 2011). Another study tells us that the
ionic liquids are known for their low volatility than that of the conventional
pretreatment chemicals used, and this proves that these ILs can proceed with the
pretreatment of the biomass at atmospheric pressure at high temperature. ILs are also
non-odorous and are relatively safer liquor, which can be easily handled (Brandt
et al. 2013). ILs have attractive characteristics as a possible replacement for conventional solvents in the separation process (Gonfa et al. 2011). Ionic liquids have
gained new attention to chemists as a green solvent for various purposes. The
toxicity analysis of 1-alkyl-3-methylimidazolium chloride-based ionic liquids was
assessed using the nematode Caenorhabditis elegans. In this toxicity analysis, where
various concentrations of the selected IL were preceded, their result is interpreted as
to understand the LC 50 /mg mL
À1 , which is represented in Table 3.3. Thus, after the
exposure of IL to the nematode, the initial chemical exposure was not fatal to the
worm, as it survived the exposure; moreover, there was successful reproduction by
the nematode, stating that the IL has a very low impact on the environmental
sustainability, especially to that of the life present on the ground (Swatloski et al.
2004). A specific ionic liquid 1-ethyl-3-methylimidazolium acetate, or known as
EMIMAc, is considered as a nontoxic, noncorrosive, and also biodegradable ionic
3 Pretreatment of Wheat Straw Using Ionic Liquids for Bioethanol Production. . .
55