Properties of the system triethylene glycol dimethyl ether- benzene-water at 30⁰C

The purpose of this investigation is to determine the density, viscosity, surface and interfacial tension, diffusivity, and refractive index of a system or benzene water containing triethylene glycol dimethyl ether at 30ºC. The samples were prepared by adding the E-161 to solutions of benzene saturated with water and solutions of water saturated with benzene to form a system of total E-161 concentration between 0 and 69 weight per cent. The samples were allowed to come to thermal equilibrium in a constant temperature bath at 30ºC. The density of the samples was determined with a pycnometer, the viscosity with an Ostwald viscosimeter, the refractive index with a dipping refractometer, the surface and interfacial tensions with the Cenco-du Nouy tensiometer, and the diffusivity was calculated by the method of Wilke.

It was found that density, viscosity, refractive index, surface and interfacial tension, and diffusivity at any point in the E-161-benzene-water system depends on the concentration of E-161, benzene, and water at that point. The curve of densities, viscosities, refractive indices, surface tensions, and diffusivities of solutions in the benzene phase approach the curve of densities., viscosities, refractive indices, surface tensions and diffusivities or solutions in the water phase as the E-161 concentration is increased to the plait point concentration. The E-16 becomes a “surface active” agent when dissolved in the water phase and tends to lower the surface tension of this phase; the E-161 becomes a “surface inactive” agent when dissolved in the benzene phase has only a slight effect on the surface tension of this phase. The interfacial tension between benzene and water phase is decreased as the concentration of E-161 in the system is increased to the plait point concentration where the interfacial tension is zero. The diffusivity was found to decrease with increased concentration of E-161.