Dehydrating Ethanol Using a Ternary Solute and Extractive Batch Distillation

Abstract

Anhydrous bioethanol is a material used in many applications including biofuel. Commonly, bioethanol is produced through sugar fermentation which results in a low concentration of ethanol. For utilization as biofuel, the lowest ethanol concentration should be 99.5%. Distillation is common technique to dry a mixture solution, however, the mixture of bioethanol and water is forming an azeotrope that limit the concentration of 96% ethanol. This paper discusses ethanol dehydration through extractive batch distillation by the addition of a ternary solute sodium hydroxide, citric acid, sulfuric acid, glycerol or ethylene glycol to ethanol. The initial concentration of ethanol used was 86% v/v, and the amount of ternary solute added was selected based on the colligative properties of the solution, which included a boiling point elevation (ΔT B) that ranged from 5 to 25 °C. All the ternary solutes could break or shift the ethanol-water azeotrope. The highest concentration of ethanol was 99.91% v/v at ΔT B = 25 °C with sulfuric acid as the ternary component. The resulted ethanol concentration exhibited a linear relationship with ΔT B , which was also affected by the boiling point of the ternary solute. This study successfully produced anhydrous bioethanol by low cost and simple distillation process.

Recent Advances in the Technologies and Catalytic Processes of Ethanol Production

“…The major steps in ethanol production via the fermentation process are the treatment of a solution containing fermentable sugars, the formation of ethanol from sugars through fermentation, and distillation for the separation and purification of ethanol [134,139,140]. The main metabolic route involved in ethanol production by fermentation is glycolysis, which converts glucose into pyruvate that is further reduced to produce ethanol and CO 2 under anaerobic conditions [65,141].…”