product formation was reported during the AHP pretreatment [25, 38, 39]. Thus, it
can be employed effectively to achieve higher lignin removal during the
pretreatment.
The use of H 2 O 2 for the pretreatment of lignocellulosic biomass is based on the
chemical reactions that this oxidizing agent undergoes in the alkaline liquid medium
[39]. Its dissociation generates the hydroperoxide anion (HOOÀ) through Eq. (1)
H 2 O 2 þ H 2 O $ HOO
À
þ H 3 O
þ
ð1Þ
In the alkaline medium, the hydroperoxide anion can react with H 2 O 2 , leading to
the formation of superoxide and hydroxyl radical, as expressed in Eq. (2).
H 2 O 2 þ HOO
À
$ OH þ O 2
À H 2 O
ð2Þ
9 Hydrolysis Employed in SCT
Bioethanol production from lignocellulosic biomasses includes processes like
pretreatment, hydrolysis, and fermentation. Pretreatment helps to alter the biomass
structure and chemical composition that aids in rapid and efficient hydrolysis of the
carbohydrates into reducible sugars. Hydrolysis is a process that converts the polysaccharides into monomeric sugars which is further taken into fermentation. It is
considered as one of the most important steps in the production of fermentable
sugars. Fermentation is carried out by organisms that can utilize this monomeric
sugar and produce ethanol wherein the organisms can be either naturally grown or
genetically modified. Cellulose in the biomass is organized into microfibrils
containing thousands of glucose residues. These celluloses can be hydrolytically
broken down into glucose either by enzymes such as cellulases or by chemicals like
sulfuric or other acids.
Hemicellulose also present in the biomass is composed of pentose and hexose
sugars being 5-carbon and 6-carbon, respectively, and they can be hydrolyzed by
enzymes such as hemicellulases or by acids to release the sugars which include
xylose, arabinose, glucose, galactose, or mannose. There are certain process configurations being carried out in order to obtain better yield of bioethanol. These
processes include separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), simultaneous saccharification and
co-fermentation (SSCF), and consolidated bioprocessing (CBP). The processes
adopted is based on the feedstock and the other process parameters which further
helps in giving higher yield of bioethanol. There are two major types of hydrolysis
processes being carried out which includes chemical reaction using acids and
enzymatic reaction.
98
S. Niju and M. Swathika
can be employed effectively to achieve higher lignin removal during the
pretreatment.
The use of H 2 O 2 for the pretreatment of lignocellulosic biomass is based on the
chemical reactions that this oxidizing agent undergoes in the alkaline liquid medium
[39]. Its dissociation generates the hydroperoxide anion (HOOÀ) through Eq. (1)
H 2 O 2 þ H 2 O $ HOO
À
þ H 3 O
þ
ð1Þ
In the alkaline medium, the hydroperoxide anion can react with H 2 O 2 , leading to
the formation of superoxide and hydroxyl radical, as expressed in Eq. (2).
H 2 O 2 þ HOO
À
$ OH þ O 2
À H 2 O
ð2Þ
9 Hydrolysis Employed in SCT
Bioethanol production from lignocellulosic biomasses includes processes like
pretreatment, hydrolysis, and fermentation. Pretreatment helps to alter the biomass
structure and chemical composition that aids in rapid and efficient hydrolysis of the
carbohydrates into reducible sugars. Hydrolysis is a process that converts the polysaccharides into monomeric sugars which is further taken into fermentation. It is
considered as one of the most important steps in the production of fermentable
sugars. Fermentation is carried out by organisms that can utilize this monomeric
sugar and produce ethanol wherein the organisms can be either naturally grown or
genetically modified. Cellulose in the biomass is organized into microfibrils
containing thousands of glucose residues. These celluloses can be hydrolytically
broken down into glucose either by enzymes such as cellulases or by chemicals like
sulfuric or other acids.
Hemicellulose also present in the biomass is composed of pentose and hexose
sugars being 5-carbon and 6-carbon, respectively, and they can be hydrolyzed by
enzymes such as hemicellulases or by acids to release the sugars which include
xylose, arabinose, glucose, galactose, or mannose. There are certain process configurations being carried out in order to obtain better yield of bioethanol. These
processes include separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), simultaneous saccharification and
co-fermentation (SSCF), and consolidated bioprocessing (CBP). The processes
adopted is based on the feedstock and the other process parameters which further
helps in giving higher yield of bioethanol. There are two major types of hydrolysis
processes being carried out which includes chemical reaction using acids and
enzymatic reaction.
98
S. Niju and M. Swathika