Etude expérimentale de l’effet de sel sur l’équilibre liquide-liquide des systèmes.

Abstract

This work comes within the framework of a research of powerful salts likely to improve the extraction of acetic acid and ethanol from an aqueous solution by using dichloromethane and ethyl acetate as solvents. In fact the presence of a salt can influence the solubility of a compound by either increasing it or decreasing it, leading to Salting-out and Salting-in, respectively. The addition of a salt in an aqueous solution introduces ionic forces which affect LLE and which influence directly the distribution coefficient of the solute. The effect of NaCl and Na2SO4 on the liquid-liquid equilibrium data of the ternary system (Water+ Acetic Acid+ Dichloromethane) at an ambient temperature of 20°C and an atmospheric pressure is studied experimentally in this work. The mass fractions of salts in the total mixture are 5%, 10% and 20%. It is noted that the equilibrium between phases is modified preferably to the extracted phase and the « Salting-out » effect of Na2SO4 is more important than the effect of NaCl. Second study is realized on the effect of KCl and the effect of NaNO3 on the equilibrium of the system (Water + Ethanol+ Ethyl Acetate). The increasing of the mass fraction of salt decreased the concentration of the solute in the aqueous phase and it’s increased in the organic phase. And the « Salting-out » effect of NaNO3 is more important than the effect of KCl. From the experimental results, it can be conclude that when the percentage of salt increases in the salt solution, the equilibrium between phases is modified in favor of the extracted phase.