Experimental studies of clay-stabilized oil-in-water emulsions

Abstract

Several experiments concerning clay-stabilized Pickering emulsions have been studied.General emulsion coalescence with and without clay was investigated with optical microscopy.It showed that clay slows down the rate of droplet coalescence.An attempt was given to demonstrate the adsorption dynamics of clay to the oil-waterinterface due to electrostatic- and Van der Waal forces. A birefringent experiment wasconducted to see the clay as it adsorbed onto the oil-water interface. From the obtainedresults, one thinks that the reflection from the meniscus is too large to observe clay at theinterface.The main experiment concerning the clay adsorption dynamics was a SAXS experimentwhere the emulsions were monitored for 1 hour immediately after emulsion preparation.From this experiment, there were no changes in the scattering, indicating that clay wasnot adsorbed to the surface of the oil droplets. An explanation for this may be that the 1hour is too little time to observe the dynamic.In parallel, clay stabilized Pickering emulsions with various clays were monitored for 2months to check stability. We observed that for the concentrations of oil and clay usedin this experiment, Laponite RD is most favorable for stabilizing emulsions. ModifiedLaponite and NaFh exhibit slightly less stability.