Page 106 - Lignocellulosic Biomass to Liquid Biofuels

82 Lignocellulosic Biomass to Liquid Biofuels

inhibited by end product (such as cellobiose and glucose). Addition of cel-
lobiase enzyme also alleviates the inhibitory effect of cellobiose as it also
hydrolyzes the cellobiose to glucose. Operating hydrolysis reaction at low
substrate concentration reduces the end product inhibition. It was observed
that glucose concentration increased with increase in dry matter loading
(up to 10% of dry matter). A further increase in dry matter concentration
does not proportionately increase the glucose yield. This may be attributed
to possible mass transfer limitations due to high substrate concentration
where there is little convective mixing due to minimum water available to
facilitate the mass transfer of the water soluble compounds. Sugars build up
around the active sites of cellulase enzyme and inhibit further hydrolysis
reaction [181]. Table 3.1 shows comparative chart for the work reported
on hydrolysis of lignocellulosic biomass [182].

Table 3.1 Comparative chart for previous work reported on hydrolysis of
lignocellulosic biomass [182].
Biomass Pretreatment and operating Lignin Cellulose
conditions removal potential
(% w/w) conversion
(% w/w)

Sugarcane Steam (205°C, 40 bar, 35 48.9
bagasse explosion 10 min)
WAO (195°C, 12 bar, 50 57.4
15 min)
Sodium 180°C, 20 min 84.3 97.5
hydroxide in 1% NaOH
liquid hot
water
Energy cane Ionic liquid 5% (w/w) 120° 32 87
bagasse ([EMIM] C 30 min
[OAc])
Rice husk APAWAO (185°C, 5 bar, 88 86
15 min)
WAO (185°C, 5 bar, 22
15 min)
Rice straw Hydrated lime 10% (w/w) Ca 27 48.5
(OH) 2
95°C, 3 h
Coastal Sodium 3% NaOH, 86 90.43
bermuda hydroxide 60 min,
grass pretreatment 121°C
APAWAO, Alkaline peroxide-assisted wet air oxidation; WAO, wet air oxidation.