Dilute acid hydrolysis of cotton stalks and ethanol production from hydrolytic liquids

Dilute acid hydrolytic condition of cotton stalks and ethanol producing from hydrolytic liquids were studied in this paper. Single factors experiments and orthogonal experiment were designed to explore effects of sulfuric acid concentration, hydrolysis time, solid-liquid ratio and hydrolysis temperature on the yield rates of xylose and glucose in the process of dilute acid hydrolysis of cotton stalks, and condition was optimized, the acid hydrolysis liquids were collected under the optimum condition and used in ethanol fermentation after detoxification, decoloration and condensation process. The ethanol fermentation parameters (concentration of reducing sugar, strain mixture proportion, original pH value, fermentation time) were examined and optimized by single factors and orthogonal design. The results showed that, the optimal dilute acid hydrolytic condition was determined as follows: sulfuric acid concentration 4.0%, hydrolysis time 30 min, solid solution ratio 1:5, and hydrolysis temperature 121°C and the optimized parameters for ethanol fermentation were identified as reducing sugar 7.0%, inoculating Saccharomyces cerevisiae and Pachysolen tannophilus with proportion 1:1, original pH value 5.0, and fermentation time between 36 h to 48 h.