Role of Macromolecules in Emulsion Stability with Special Reference to Pepsin as Emulsifier

Abstract

Abstract Role of pepsin as emulsifier in the stability of Nujol-in-water system has been studied. The flocculation studies were carried out haemocytometrically at different pH values, different amounts of electrolytes and different amounts of emulsifier itself. The zeta potential measurements were carried out at different pH values and varying amounts of electrolytes. In the light of the D. V. O. theory the interaction energy profiles have been drawn by summing up the repulsion and attraction energies. The high energy barriers obtained obviate the possibility of the occurrence of the flocculation in the primary minima. It appears, therefore, that the reversible flocculation occurs in the secondary minima which are about 2 to 4 kT deep. Therefore, assuming a singlet-doublet equilibrium degrees of aggregations have been calculated. In order to explain the observed values of degrees of aggregations, A (van der Waals constant) should be ≈5.97×10−13 erg. This value has been obtained by an indirect approach to fit the aggregation data. In case of Al(III) and Th(IV), however, charge reversal takes place which has been explained by a model picture. Charge densities and binding parameters have also been calculated.