Abstract:
The effect of microwave-assisted alkaline (MWA)pretreatments and acid hydrolysis of
lignocellulosic Wheat Straw were investigated. Pretreatment is a major step for the
efficient and effective biochemical conversion of lignocellulosic biomass to biofuel.
Microwave-assisted alkali (MWA) pretreatment is one of the promising techniques used
in the bioconversion of biomass into useful energy product.
In the recent years, bioethanol derived from lignocelluloses biomass as an alternative to
the conventional fuels is becoming a focus of many researchers. In this study, Wheat
Straw (WS) is used as a feedstock for the production of total reducing sugars via
Microwave assisted alkaline (MWA) pretreatment and acid hydrolysis process.
Specifically, the focus is mainly on the investigation of the effect of Microwave assisted
alkaline (MWA) pretreatment on the yield of total reducing sugar from Wheat Straw
(WS) biomass using (3.5% NaOH) sodium hydroxide as a catalyst. Alkali concentration,
pretreatment temperature are fixed while the pretreatment time were varied in
conventional alkali pretreatment. On the other hand, Microwave Power and time were
varied in the Microwave assisted alkaline (MWA) pretreatment experiments. Following
the pretreatment, dilute sulfuric acid hydrolysis of Wheat Straw was carried out for the
comparison of total reducing sugar yields. The raw and pretreated Wheat Straw were
characterized for their composition using NREL and ASTM protocols. The pretreated
Wheat Straw was estimated for its reducing sugar yield via dilute acid hydrolysis (at
2.5% concentration) at a temperature of 121
o
C and contact time of 1hr using DNS
method. It is found that, the raw Wheat Straw has a composition of 40.9% cellulose,
26.2% hemicelluloses, and 17% Lignin. A maximum lignin removal is 72.94% and
cellulose recovery of 79.31% were achieved with microwave assisted alkali (MWA)
pretreatment at 700W and time of 25minute. And also in alkali pretreatment lignin
removal 58.88%, cellulose recovery 73.13% and time of 60 minute. The maximum
reducing sugar of 495.01 mg/g was experiential for sample pretreated with Microwave
assisted alkali (MWA) at 700W and 25minute interaction time compared to 441.00 mg/g
for alkali pretreated operated 100
o
C and 60 minute using dilute sulfuric acid hydrolysis.
Keywords: Agricultural waste; wheat straw; lignocelluloses biomass; Microwave
Irradiation power, Pretreatment, Total reducing sugar.