Page 95 - Lignocellulosic Biomass to Liquid Biofuels

Bioconversion of lignocellulosic biomass to bioethanol and biobutanol 71

alkaline can split the alkali labile bond between lignin and carbohydrate.
1-Ethyl-3-methylimidazolium acetate, [EMIM]oAc, was also used for
softwood (southern yellow pine) treating, and yield of 31% of original lig-
nin as carbohydrate free and 38% as carbohydrate bond was attained.
Pinkert et al. [19] reported the process of delignification, isolation of Pinus
radiata wood lignin, and retention of crystalline structure of cellulose in
carbohydrate-rich filtrate by treating the wood flour with imidazolium
acesulfamate ionic liquids, that is, [EMIM]Ace and [BMIM]Ace, which
are derived from commercial sugar acesulfamate potassium. The impact of
different variables, such as wood species, water content, wood particle
size, and type of IL cation plus reusing of IL on lignin extraction effi-
ciency (mass of extracted lignin/mass of initial lignin content) with
[BMIM]Ace, has been studied. Increasing the extraction temperature from
353 to 416K and extraction time from 1 to 4 h raises the extraction effi-
ciency from 0.32 to 0.81 and 0.05 to 0.07, respectively.
Removal efficacy decreases as the water content in the atmosphere
resulting from dry condition (inert gas) to normal atmosphere and grow-
ing the moisture content in atmosphere. It increases 13% for [EMIM]Ace
treatment than [BMIM]Ace treatment at 373K; 2 h of pretreatment is
done due to two reasons: first, the presence of shorter alkyl substituent in
[EMIM]Ace as compared to [BMIM]Ace, which declines its toxicity and
viscosity resulting increases mobility to enhance IL biomass interface; and
second, the existence of more halide impurity in [EMIM]Ace, which has
a positive impact on IL lignin interaction. All the studies reveal the effi-
cacy of ionic liquid, as a green and environment favorable solvent to treat
the lignocellulosic biomass. Finally, it is being used to remove and recover
lignin adequately which is the second most plentiful biological constituent
in the world next to cellulose and hemicellulose.

3.2 Suitable strains and their productivity

Bioalcohols, such as bioethanol, biobutanol (or biogasoline), and propa-
nol, are used as liquid transportation fuels obtained through the biomass
aerobic or anaerobic fermentation.
The sustainable production of liquid fuels and chemical products
through biorefinery approaches is based on feedstocks as lignocellulosic
biomass that is widely available from agriculture by-products and industrial
residues.