چكيده به لاتين
Bioethanol, as the most common form of biofuel, is considered a key alternative to fossil fuels, capable of being blended with gasoline up to 20% without requiring engine modification. In addition to increasing octane number and reducing engine knocking, it contributes to lowering emissions of pollutants such as carbon monoxide and unburned hydrocarbons. This study aimed to optimize bioethanol production from sugarcane molasses with a focus on improving yield and reducing production costs. Following preliminary trials, a response surface methodology was employed to design the experiments, considering initial sugar concentration, fermentation time, and pH as the main variables. Vacuum fermentation was applied in 12-hour intervals for one hour each, as a strategy for in-situ ethanol removal, alleviation of inhibitory effects, and enhancement of sugar-to-ethanol conversion. The thermal and electrical energy required for the process was supplied through a hybrid renewable system consisting of photovoltaic panels, parabolic trough collectors, and a solar-powered water desalination unit. Results showed that under optimized conditions (43% Brix, pH 5.5, and 71 hours), bioethanol was produced at a concentration of 11.86% v/v with a yield of 93%. In contrast, under control conditions (no vacuum applied), only 9.7% v/v ethanol was produced with a yield of 35%. Additionally, although Chlorella vulgaris biomass fermentation resulted in a high yield of 97%, the final ethanol concentration was only 7.4 g/L due to challenges in glucose extraction and biomass cultivation. evaluation of E10 fuel derived from the produced bioethanol revealed a 4.25% increase in torque, a 23% reduction in carbon monoxide, and a similar decrease in unburned hydrocarbons, though specific fuel consumption and exhaust gas temperature increased by 12.5% and 7.8%, respectively. From an environmental perspective, higher ethanol production within a fixed reactor volume led to reduced water consumption per liter of ethanol and consequently decreased wastewater generation. Overall, the findings of this research confirm that vacuum fermentation is an effective strategy for enhancing performance, environmental sustainability, and economic efficiency in industrial bioethanol production.
