Simulation of flocculation in W/O emulsions and experimental study
Abstract The flocculation of aqueous droplets in W/O emulsions has been studied using Langevin dynamics simulation. The range of aqueous phase concentrations and time necessary for the formation of percolation clusters were determined. Percolation clusters are not formed if aqueous phase concentrations in simulated emulsions are less than 0.15. In emulsions with aqueous phase concentrations from 0.15 to 0.3–0.4 the percolation cluster is formed within 2 s, but the rate of the subsequent attaching droplets and small aggregates to this cluster is low. In simulated emulsions with aqueous phase concentrations of above 0.3–0.4, almost all droplets are combined into percolation clusters within a few fractions of a second. Experimental data were compared with the results of computer simulations. In emulsions with aqueous phase concentrations of above 0.15 the droplet flocs form a network structure in the oil phase, and the rate of oil phase release depends on the rate of oil drainage. In less concentrated emulsions, the separation into a more concentrated W/O emulsion and a diluted W/O emulsion containing small flocs of aqueous droplets takes place. The data obtained suggests that the simulation by the Langevin dynamics method makes it possible to predict the stability of W/O emulsions to flocculation and subsequent sedimentation.