BUILT AND SURFACE-PROPERTIES FOR THE METHANOL-1,1-DIMETHYLPROPYL METHYL-ETHER AND METHANOL-1,1-DIMETHYLETHYL METHYL-ETHER SYSTEMS

Bulk (vapour-liquid equilibrium data) and surface (surface tension) pr operties of the mixtures formed by methanol and the branched ethers 1, 1-dimethylpropyl methyl ether (tert-amyl methyl ether or TAME) and 1,1 -dimethylethyl methyl ether (tert-butyl methyl ether or MTBE) have bee n studied. A Gibbs-Van Ness type apparatus for total vapour pressure m easurements was used to obtain vapour-liquid equilibria (VLE) data for methanol-TAME at 298.15 and 318.15 K. The system shows positive devia tions from Raoult's law with an azeotrope. The surface tension, gamma, for methanol-TAME and methanol-MTBE mixtures was measured at 298.15 a nd 308.15 K. Values for the relative surface adsorption calculated fro m the surface tension and the chemical potentials indicate that the su rface is enriched in ether. The lattice-fluid, the lattice-fluid assoc iated solution, and the extended real association solution models have been used to describe the bulk properties of the methanol-TAME mixtur es. The model proposed by Rice and Teja has been used to describe the surface tension of the methanol-MTBE and methanol-TAME mixtures.