Optimization of alkaline pretreatment conditions for enhancing glucose yield of rice straw by response surface methodology

Response surface methodology (RSM) was employed to optimize alkaline pretreatment condition for maximum glucose yield of rice straw with respect to NaOH concentration (1.0–4.0%), reaction temperature (60−100 °C) and pretreatment time (30−90 min). The maximum glucose yield of 254.5 ± 1.2 g kg−1 biomass was obtained at the desirable pretreatment condition of 2.96%, 81.79 °C and 56.66 min. The ANOVA test revealed that the model and all independent parameters were considered statistically significant at 95% confidence level. Furthermore, we tried to explore the effect of ultrasonication on alkaline pretreatment. The sample treated with both NaOH and ultrasound at high power showed a slightly higher digestibility yield than the sample with NaOH at 80 °C, but the difference was not significant.