Coacervation (liq./liq. sepn.) takes place in aq. solns. contg. short chain tetraalkylammonium (TAA) and silicate ions when other ions (Na+, Br-) are present. The TAA bromide is predominantly present in the upper layer and the Na silicate is mainly present in the lower layer. The coacervation can be described using the activity coeffs. of the 2 sep. salts and a Redlich-Kister type excess Gibbs free energy. Since part of the Gibbs free energy is dependent on the enthalpy of hydrophobic hydration of the TAA ions, the driving force for coacervation is ascribed to a mismatch of the hydration layers around the silicate and TAA ions. [on SciFinder (R)
