Effect of pretreatment on the ethanol and fusel alcohol production during fermentation of sugarcane press-mud

Abstract

Diminishing fusel alcohol content on bioethanol streams is a challenge that must be overcome to increase hydrogen (H2) yield by ethanol steam reforming (ESR). Herein, a split plot experimental design was used to assess the effect of temperature and HNO3 loadings, during the pretreatment of sugarcane press-mud for subsequent fermentation, over both ethanol and fusel alcohol content. Results showed that pretreatment temperature has an important effect on ethanol concentration during fermentation owing to the formation of reducing sugar during pretreatment. The highest both ethanol (64 g L−1) and fusel alcohol (547 mg L−1) content were obtained at 130 °C without HNO3. But, at 130 °C, the addition of 16 g HNO3 kg−1 solid reduced the ethanol and fusel alcohol concentrations by 3.5 % and 20 %, respectively. Therefore, HNO3 did have an important effect on the fusel alcohol production, but a small effect on the ethanol concentration after fermentation. Under said pretreatment conditions (i.e., 130 °C and 16 g HNO3 kg−1 solid), a possible production of 5.46 g H2 kg−1 of sugarcane press-mud was calculated from mass balance and empirical correlations. Therefore, the addition of HNO3 during biomass pretreatment could enhance further H2 production by ESR.