Why does water-in-oil emulsion (emulsifier added) unstable at very high temperature?
this technique is used in the dehydration of crude oil, ie treat emulsions to give water and oil. The natural emulsifier is naphthenic acids which are various MW carboxylic acids which by intimate mixing with water it brings in hydrogen bonding of water and the hydrophobic chain on the Naphthenic acids take the water, emulsified into the oil, Normally we will add an antiemulsifier to break the natural emulsions, this chemical is called a demulsifier, In you case you added an emulsifier. There are a couple processes going on here; 1> heat causes the water droplets now say at 1-2 microns size to vibrate and in so doing the water drops coalesce from 1 u to large microns going to over 30 u. The water drops being large now are heavy and falls down through the oil. 2> The collection of water coalescing becoming heavier starts to accumulate to the interface with oil -water. At this interface the bulk water attracts the water droplets which may still have a few molecules of surfactants attache
