An approach to the utilisation of CO(2 )as impregnating agent in steam pretreatment of sugar cane bagasse and leaves for ethanol production

BACKGROUND: The conditions for steam pretreatment of sugar cane bagasse and leaves were studied using CO(2 )as an impregnating agent. The following conditions were investigated: time (5 to 15 min) and temperature (190 to 220°C). The pretreatment was assessed in terms of glucose and xylose yields after enzymatic hydrolysis and inhibitor formation (furfural and hydroxymethylfurfural) in the pretreatment. Results from pretreatment using SO(2 )as impregnating agent was used as reference. RESULTS: For sugar cane bagasse, the highest glucose yield (86.6% of theoretical) was obtained after pretreatment at 205°C for 15 min. For sugar cane leaves the highest glucose yield (97.2% of theoretical) was obtained after pretreatment at 220°C for 5 min. The reference pretreatment, using impregnation with SO(2 )and performed at 190°C for 5 min, resulted in an overall glucose yield of 79.7% and 91.9% for bagasse and leaves, respectively. CONCLUSIONS: Comparable pretreatment performance was obtained with CO(2 )as compared to when SO(2 )is used, although higher temperature and pressure were needed. The results are encouraging as some characteristics of CO(2 )are very attractive, such as high availability, low cost, low toxicity, low corrosivity and low occupational risk.