Microwave hydrothermal hydrolysis was carried out using a
domestic microwave oven with a frequency setting of 2450 MHz.
The biomass and liquid loading ratio was fixed at 1:12 for the
experiments. Ten grams of dried SPW was submerged in 120 g of
deionized water in a 500-mL conical flask for the first run. Additionally,
10 g CO2 (dry ice) was also added for the second run.
Immediately after adding dry ice, the conical flask was closed by
rubber stopper and kept for 15 min until the dry ice is completely
dissolved. Then, the flask with loosened cap was placed at the center
of rotating circular plate in the microwave oven. Hydrothermal
hydrolysis without and with CO2 was carried out at different
microwave power rating of 550, 700 and 900W for 1, 2, 3 and
5 min of microwave heating. The microwave hydrolysis carried
out at 700 W/3 min without CO2 and with CO2 was designated as
7MH1 and 7MH2, respectively. Moreover, the microwave hydrolysis
carried out at 900 W/2 min without CO2 and with CO2 was designated
as 9MH1 and 9MH2, respectively. Samples were taken out
to determine the concentration of glucose and byproduct such as
acetic acid, HMF and furfural by HPLC. Glucan, xylan and lignin
content after hydrolysis were also determined according to the
NREL’s analytical methods (LAP # 42618