2.1.2 Chemical Conversion Technologies
Chemical pretreatment is utilized to attain the chemical
destruction of organic lignocellulosic waste by using organic
solvents, alkalis, strong acids, and ionic liquids. The chemical pretreatment effectiveness varies with the category of
technique used and the nature of the substances. This
degeneration viability for lightweight precursor or dietary
supplements with high carbohydrate content because their
rate of degradation increased and they accumulate as volatile
acids leading to methanogenesis failure although it enhances
the biodegradation of lignocellulosic substrates having more
lignin amount (Paudel et al. 2017).
Alkaline
Alkaline pretreatment comprises adding alkali bases like
calcium hydroxide (CaOH), potassium hydroxide (KOH),
sodium hydroxide (NaOH), ammonium hydroxide
(NH 4 OH), aqueous ammonia, and hydrogen peroxide
(H 2 O 2 ) to lignocellulosic biomass, leading to increase inner
surface area via swelling, reduction in the degree of polymerization, and its crystalline structure and causes breakage
of linkage among lignin and its polymers. This method
works better when biomass has low lignin content but with
increased lignin content this method becomes less efficient.
So, the efficiency of this treatment depends upon the lignin
quantity of biomass. This method is useful in such a way it
causes partially lignocellulosic biomasses hydrolysis. Up till
now, sodium hydroxide and potassium hydroxide are efficient alkaline treatments to improve waste digestibility
(Amin et al. 2017; Paudel et al. 2017).
Acidic
Acidic pretreatment of lignocellulosic biomass involves the
usage of inorganic and organic acids like hydrochloric acid,
phosphoric acid, nitrous acid, nitric acid, sulfuric acid,
CH 3 COOH, formic acid HCOOH, for hydrolysis of
enzymes, and lignocellulosic biomass (Niphadkar et al.
2018). Acidic pretreatment was carried out with acid in
Fig. 1 Pretreatment method for
lignocellulosic biomass
Bioconversion of Agro-Industrial Waste into Value-Added Compounds
353
Chemical pretreatment is utilized to attain the chemical
destruction of organic lignocellulosic waste by using organic
solvents, alkalis, strong acids, and ionic liquids. The chemical pretreatment effectiveness varies with the category of
technique used and the nature of the substances. This
degeneration viability for lightweight precursor or dietary
supplements with high carbohydrate content because their
rate of degradation increased and they accumulate as volatile
acids leading to methanogenesis failure although it enhances
the biodegradation of lignocellulosic substrates having more
lignin amount (Paudel et al. 2017).
Alkaline
Alkaline pretreatment comprises adding alkali bases like
calcium hydroxide (CaOH), potassium hydroxide (KOH),
sodium hydroxide (NaOH), ammonium hydroxide
(NH 4 OH), aqueous ammonia, and hydrogen peroxide
(H 2 O 2 ) to lignocellulosic biomass, leading to increase inner
surface area via swelling, reduction in the degree of polymerization, and its crystalline structure and causes breakage
of linkage among lignin and its polymers. This method
works better when biomass has low lignin content but with
increased lignin content this method becomes less efficient.
So, the efficiency of this treatment depends upon the lignin
quantity of biomass. This method is useful in such a way it
causes partially lignocellulosic biomasses hydrolysis. Up till
now, sodium hydroxide and potassium hydroxide are efficient alkaline treatments to improve waste digestibility
(Amin et al. 2017; Paudel et al. 2017).
Acidic
Acidic pretreatment of lignocellulosic biomass involves the
usage of inorganic and organic acids like hydrochloric acid,
phosphoric acid, nitrous acid, nitric acid, sulfuric acid,
CH 3 COOH, formic acid HCOOH, for hydrolysis of
enzymes, and lignocellulosic biomass (Niphadkar et al.
2018). Acidic pretreatment was carried out with acid in
Fig. 1 Pretreatment method for
lignocellulosic biomass
Bioconversion of Agro-Industrial Waste into Value-Added Compounds
353