1998 Volume 31 Issue 5 Pages 749-757
The effect of the salts sodium chloride, calcium chloride and zinc chloride on the vapor-liquid equilibria (VLE) of three miscible binary system viz., benzene-pyridine, water-pyridine and methanol-benzene has been experimentally investigated at atmosphere pressure using a Smith and Bonner type of equilibrium still. The salts were dissolved in the solvent in which they are preferentially soluble, to concentrations upto 20 percent by weight wherever possible. In the case of benzene-pyridine system, the salts calcium chloride and zinc chloride cause the “salting out” of benzene. As for the azeotropic system, water-pyridine, while sodium chloride increases the pyridine content in the vapor phase, calcium chloride and zinc chloride bring about “salting out” of water and “phase splitting”. In respect of the third binary, methanol-benzene which is also azeotropic, shift in the azeotropic composition and ‘crossover effect’ are observed upon addition of calcium chloride and zinc chloride. The experimental VLE data have been correlated using Wilson and NRTL models after ascertaining their thermodynamic consistency.