Mutual Solubilities of Cyclohexane and Water in Aqueous Methyldiethanolamine /Cyclohexane Liquid-Liquid Equilibria

The aim of this work is to study the solubility of cyclohexane in aqueous methyldiethanolamine (MDEA) solutions. Thermostated jacketed double glass equilibrium cells were used to measure the mutual solubility between two liquid phases of aqueous MDEA and cyclohexane at 298-318 K under atmospheric pressure. The cyclohexane solubility in the aqueous liquid samples was analyzed using GC-MS coupled with purge and trap technique, while that of water in the cyclohexane-rich phase was measured via the Karl-Fischer titration method. It was observed that the solubility of cyclohexane in the aqueous phase increases with increasing temperature. Furthermore, an increase in amine composition, increases the solubility of cyclohexane. The mutual water solubility in the cyclohexane-rich phase increases rapidly with increasing temperature while it was rather nonsensitive toward the amine composition. A simple correlation for the salting-in ratio has been used that allows for a direct comparison between the solubilities of cyclohexane in aqueous solutions of MDEA to those in pure water at various temperatures.