Fig. 8From: Optimization of biomass pretreatments using fractional factorial experimental designResponse surfaces indicating the characteristics of the sugar release as a function of the two most important factors for EO samples: ethanol and catalyst concentrations, both in step 2. The other factors were kept constant in a [H2SO4] in step 1 = 1%; temperature of step 2 = 160 °C and time of step 2 = 90 min, and in b [H2SO4] in step 1 = 0% v/v; temperature of step 2 = 160 °C and time = 60 min)Back to article page