PRECIPITATION OF CALCIUM-CARBONATE AND CALCIUM-FLUORIDE IN MICROEMULSIONS - CALORIMETRIC INVESTIGATION

The enthalpies of precipitation of calcium carbonate and calcium fluor ide in water/sodium bis-2-ethylhexyl sulfosuccinate/n-heptane, water/d idodecyldimethylammonium bromide/n-heptane and water/tetraethyleneglyc ol-mono-n-dodecyl ether/isooctane microemulsions were measured by a ca lorimetric technique. The results indicate that the energetic state of CaCO3 and CaF2 nanocrystals encapsulated in the aqueous microregions of these microemulsions is strongly different from that in bulk water. Effects due to the smallness of the nanocrystals, interactions betwee n nanocrystals and water/surfactant interfaces and changes of the ther modynamic parameters in nanoscopic water environments are discussed.