Equilibration in a tartaric acid emulsion system

The equilibration between phases in an emulsion of tartaric acid stabilized by a commercial non-ionic surfactant, Laureth 4, was studied by contacting layers of water, tartaric acid and surfactant and measuring the change of layer heights with time. ry to earlier results of similar investigations with salicylic acid, the present determinations disclosed the transfer of compounds between the solid acid phase and the liquids not to be the primary rate-determining step in the equilibration process. Instead this stage was found in the surfactant liquid and the aqueous solution of the acid generating a lamellar liquid crystal. The results revealed a surprising number of different mechanisms involved in the transfers of compounds between the phases as exemplified by the fact that initially the formed liquid crystal was dispersed in the aqueous liquid forming a birefringent layer, a significant fraction of which was the aqueous phase. At intermediate times in the process a fraction of liquid crystal from the aqueous layer was redispersed into the surfactant liquid, in which the newly generated liquid crystal was also dispersed, but now the birefringent parts were of a more complex structure. In the final stage of the investigation but little liquid crystal was produced and the birefringent generating elements in the surfactant liquid layer were spontaneously redispersed into a liquid crystal in the aqueous stratum.