Approximation of the Separation Boundary in the Water-Hydrotrope-Oil Ternary Systems

In this work, we studied the ternary systems water – 2-butoxyethanol – toluene, water – methanol – chloroform and water – methanol – dichloromethane. The separation boundary was experimentally located and approximated by various functions. The main reasons are revealed that prevent a satisfactory approximation of the separation boundaries by empirical functions with a small number of optimized parameters. It is found that the approximation of the separation boundaries in ternary systems can be carried out by polynomial and piecewise smooth functions with an error comparable to the uncertainty of the measurement.