To determine optimum pretreatment conditions, experiments were conducted
with different concentrations of sodium hydroxide (0–0.8 M) at various temperatures
(50–100 ◦C) and different flow rates of solution (72–120 mL/min) when
biomass feeding rate and twin-screw rotation speed were fixed at 12 g/min and
100 rpm, respectively. After pretreating the biomass, samples were washed with tap
water, dried for biomass composition analysis [21], and used in further experiments