No abstract

No abstract

No abstract

No abstract

In this work, steam explosion was used a pretreatment method to improve the conversion of elephant grass (Pennisetum purpureum) to cellulosic ethanol. This way, enzymatic hydrolysis of vaccum-drained and water-washed steam-treated substrates was carried out with Penicillium echinulatum enzymes while Saccharomyces cerevisiae CAT-1 was used for fermentation. After 48 h of hydrolysis, the highest yield of reducing sugars was obtained from vaccum-drained steam-treated substrates that were produced after 10 min at 200 °C (863.42 ± 62.52 mg/g). However, the highest glucose yield was derived from water-washed steam-treated substrates that were produced after 10 min at 190 °C (248.34 ± 6.27 mg/g) and 200 °C (246.00 ± 9.60 mg/g). Nevertheless, the highest ethanol production was obtained from water-washed steam-treated substrates that were produced after 6 min at 200 °C. These data revealed that water washing is a critical step for ethanol production from steam-treated elephant grass and that pretreatment generates a great deal of water soluble inhibitory compounds for hydrolysis and fermentation, which were partly characterized as part of this study.

No abstract

The steam explosion was carried out in the absence (autohydrolysis) and presence of phosphoric acid to evaluate the effects of temperature (180 and 210 °C), acid concentration (0 and 19 mg g -1 , dry basis) and pretreatment time (5 and 10 min) on the structure and reactivity of sugarcane bagasse. Glucan recovery was used as the main response factor for pretreatment optimization through a central composite design. Autohydrolysis at 210 °C for 10 min had a good pretreatment performance but phosphoric acid catalysis (19 mg g -1 ) resulted in better yields under considerably milder conditions (180 °C, 5 min). Hydrolysis of both substrates for 96 h using 8 wt.% total solids and 30 mg g -1 Cellic ® CTec2 (Novozymes) provided total glucose yields of 75% in average. The production of cellulosic ethanol was assessed by both separate and simultaneous hydrolysis and fermentation using Saccharomyces cerevisiae. Freeze-drying of pretreatment water solubles reduced the concentration of furfural, hydroxymethylfurfural and acetic acid by more than 80% and this eliminated their inhibitory effect on yeast fermentation.

No abstract