Effect of some cationic detergents on the macromolecular stabilised emulsion with special reference to pepsin as emulsifier

Abstract

The effect of some cationic detergents viz Phenyl Trimethyl Ammonium Chloride, Lauryl pyridinium chloride, Cetyl pyridinium Bromide and Aerosol C-61, on the nujol/water emulsion stabilised by pepsin, has been studied. The detergents were added in two ways: 1. before emulsification; 2. after emulsification. The results were compared by their flocculation concentrations obtained at zero point of charge. From these values it is observed that the flocculation concentrations before emulsification are higher than those obtained after emulsification. The stability of the present system is discussed in the light of DVO theory. The high potential energy barriers obtained obviated the possibility of flocculation in primary minima. Therefore, to explain the results, the flocculation was assumed to occur in the secondary minima. The flocculation studies were carried out haemocytometrically which enabled to calculate the degrees of aggregation (D). In order to account for the observed values of D, the effective van der Waals constant of the system should be 1.0×10−12 erg. The binding parameters and free energies have also been calculated.