Banerji and co-workers [14] found that dilute sulphuric
acid (below 30 g kg1) liberated more 5-carbon sugars than 6-
carbon sugars from sweet sorghum bagasse while Heredia-
Olea and co-workers [15] reported more 6-carbon sugars
liberated than 5-carbon sugars. Both authors from literature
made use of an enzymatic hydrolysis step after dilute acid
pretreatment to obtain the high sugar yields reported. In this
study, no enzymatic hydrolysis step was used, but the sugars
reported are the result of only the dilute acid microwave
assisted pretreatment step. Celluloses and hemicelluloses are
tightly bonded to lignin in the plant wall by covalent and
hydrogen bonding [16]. Cellulose contains ordered b-D-glucopyranose
functional groups joined together by b-(1,4) glycosidic
bonds [16,17]. Cellobiose is the main repeating unit of
cellulose and consists of two glucose molecules [17]. The hydroxyl
groups found in cellulose cross link with other hydroxyl
groups in cellulose chains resulting in the formation of
microfibrils [11,16] that make cellulose recalcitrant. The linear
structure of cellulose is caused by the hydrogen bonds within
the microfibrils and the crystallinity arises as a result of interchain
hydrogen bonds [17]. The inter-chain hydrogen bonds
thus needs to be broken to reduce crystallinity, resulting in
cellubiose units that then needs to be further broken down to
glucose.
Hemicellulose is a not crystalline and consists of branched
polymer chains of pentose, hexose and acetylated sugars. The
units found most often in the hemicellulose of plant materials
are xylose, arabinose, mannose, glucose and galactose.
Hemicellulose is difficult to break down into its monomeric
sugars due to the branched nature of the polymer chains.
Microwave irradiation works through the passage of nonionising
radiation in the range of 2.5 GHz through a liquid or
solid medium. In the case of this study, the radiation passed
through the acid in water solution as well as the solid biomass.
The radiation is absorbed by the water molecules, causing
dielectric heating of the acid in water solution while some of
the radiation is absorbed by the molecules of the biomass
causing increased vibration of the bonding between molecules.
From a purely engineering perspective, it is believed
Banerji and co-workers [14] found that dilute sulphuric
acid (below 30 g kg1) liberated more 5-carbon sugars than 6-
carbon sugars from sweet sorghum bagasse while Heredia-
Olea and co-workers [15] reported more 6-carbon sugars
liberated than 5-carbon sugars. Both authors from literature
made use of an enzymatic hydrolysis step after dilute acid
pretreatment to obtain the high sugar yields reported. In this
study, no enzymatic hydrolysis step was used, but the sugars
reported are the result of only the dilute acid microwave
assisted pretreatment step. Celluloses and hemicelluloses are
tightly bonded to lignin in the plant wall by covalent and
hydrogen bonding [16]. Cellulose contains ordered b-D-glucopyranose
functional groups joined together by b-(1,4) glycosidic
bonds [16,17]. Cellobiose is the main repeating unit of
cellulose and consists of two glucose molecules [17]. The hydroxyl
groups found in cellulose cross link with other hydroxyl
groups in cellulose chains resulting in the formation of
microfibrils [11,16] that make cellulose recalcitrant. The linear
structure of cellulose is caused by the hydrogen bonds within
the microfibrils and the crystallinity arises as a result of interchain
hydrogen bonds [17]. The inter-chain hydrogen bonds
thus needs to be broken to reduce crystallinity, resulting in
cellubiose units that then needs to be further broken down to
glucose.
Hemicellulose is a not crystalline and consists of branched
polymer chains of pentose, hexose and acetylated sugars. The
units found most often in the hemicellulose of plant materials
are xylose, arabinose, mannose, glucose and galactose.
Hemicellulose is difficult to break down into its monomeric
sugars due to the branched nature of the polymer chains.
Microwave irradiation works through the passage of nonionising
radiation in the range of 2.5 GHz through a liquid or
solid medium. In the case of this study, the radiation passed
through the acid in water solution as well as the solid biomass.
The radiation is absorbed by the water molecules, causing
dielectric heating of the acid in water solution while some of
the radiation is absorbed by the molecules of the biomass
causing increased vibration of the bonding between molecules.
From a purely engineering perspective, it is believed
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