Industrial preparation of ethanol involves the fermentation of carbohydrates such as glucose, sucrose, and starch, followed by the distillation of the product. The fermentation process begins with the addition of enzymes such as amylase and glucanase to the carbohydrate solution. These enzymes break down the carbohydrates into simpler sugars such as glucose and fructose. Yeast is then added, which converts the sugars into ethanol and carbon dioxide. The carbon dioxide is separated from the ethanol and the ethanol is then distilled to purify it. The distillation process separates the ethanol from other impurities and produces a concentrated ethanol solution. This solution is then dehydrated to produce anhydrous ethanol with a purity of up to 99.5%.
The overall reaction can be represented by the following equation:
rbohydrate + Enzyme → Glucose/Fructose → Yeast → Ethanol + Carbon Dioxide