EFFECT OF SALT MAGNESIUM CHLORIDE ON VAPOUR - LIQUID EQUILIBRIA OF BINARY AZEOTROPIC LIQUID MIXTURE: ETHYL ACETATE – ETHANOL

Abstract

Separation of azeotropic liquid mixtures using distillation is a challenging task for process engineers. A straight distillation is not useful for complete separation of mixture components for azeotropic liquid mixtures. The conventional process using liquid entrainer is energy intensive and involves running extra distillation column. The salt which dissolve in liquid mixture but has different solubility in components of liquid mixture can be used as the extracting agent like that of liquid entrainer. The added salt can hold the component in equilibrium liquid phase which has more solubility and hence can enrich the equilibrium vapour phase with the other component. Therefore the added salt has the capability to alter the relative volatility of liquid mixture. The Vapour – Liquid Equilibrium data indicates the relative amount of components in liquid and vapour phase and hence indicates extend up to which liquid mixture can be separated using distillation. In this paper we have studied the separation of one of the important azeotropic liquid mixture Ethyl Acetate –Ethanol in presence of salt Magnesium Chloride. The Vapour – Liquid Equilibrium (VLE) data of binary liquid mixture Ethyl Acetate (A)- Ethanol (B) without salt and with salt is obtained experimentally by using modified Othmer’s still. The system found to forms the minimum boiling azeotrope at 0.550 mole fraction of ethyl acetate at 71.7 0 C under the normal atmospheric pressure. The effect of addition of salt Magnesium Chloride (MgCl 2) has been studied on the vapour - liquid equilibria of ethyl acetate- ethanol. Two different compositions of salt (20% and 25% by weight of ethanol in mixture) have been tried and corresponding shift in azeotropic point towards the higher composition of ethyl acetate than without salt is noted.