Ionic liquids (ILs) are being considered as favourable solvents for liquid-liquid extraction. Ternary phase equilibria containing the ionic liquid based systems have been reported in the literature for aromatic-aliphatic-IL as well as aliphatic-alcohol-IL ternary systems. In this work global optimization has been used for the prediction of UNIQUAC interaction parameters for IL based systems. The twin concepts of closure equation and global optimization via Genetic Algorithm (GA) have been benchmarked and tested on 88 aromatic and 28 hydrogen bonding multicomponent systems. For the aromatic systems the rmsd values obtained with closure equation are similar to 20 percent better than without closure equation and similar to 50 percent better than literature. Similarly for hydrogen bonding systems with closure equation gives similar to 20 percent better rmsd values than without closure equations with an overall improvement of similar to 60 percent. After this rigorous testing we have applied this procedure on 29 imidazolium based IL ternary systems. Improvements in rmsds with closure have been similar to 6 percent better than without closure.