The isothermal solubility and physico-chemical properties(density,refractive index)of ternary system RbCl-EtOH-H 2 O at 25℃and 50℃have been firstly inve stigated by means of self-made micro-equilibrium and sampling apparatus .The compositio ns of liquid and solid at equilibrium state were determined,and the probl em of analysis of ethanol content in syste m was properly solved.The phase diag ram was drawn by the TPD phase-diagra m computer program developed by us.Three empirical formulae were propose d to correlate the solubility,density and refractive index respectively.No d emixing phenomena was observed in th e range of temperature related in thi s study.
The phase diagrams of the CH3CH2OH-Cs2CO3-H2O system were determined at 10, 30 and 50 ℃, respectively. It was found that the effect of the temperature on the phase equilibrium was insignificant within the investigated range. The binodal curves were given using a five-parameter equation and the tie lines were fitted using the Oth-mer-Tobias and Bancroft correlations. Correlation coefficients (R) for all equations exceeded 0.99. Samples of the solid phase at 30 ℃ were analyzed by TGA showing that it consisted of Cs2CO3·3.5H2O. The refractive index of the systems was also determined.
Liquid-liquid equilibrium of the poly （ethylene glycol）（PEG）-Cs2SO4-H2O aqueous two-phase system,with PEG of molecular weigth 1000,4000 and 10000,was measured at 298.15 K.The binodal curves were obtained using a four-parameter equation,and the tie lines were satisfactorily described using the Othmer-Tobias and Bancroft equations.These equations were used to develop a mathematical model for interpretation of the equilibrium data of these aqueous two-phase systems（ATPS）.It was found that an increase in the molecular weight of the PEG produced a displacement of the binodal curve toward the origin and decreased the-phase zone.
