Bulk and surface properties for the methanol–1,1-dimethylpropyl methyl ether and methanol–1,1-dimethylethyl methyl ether systems

Abstract

Bulk (vapour–liquid equilibrium data) and surface (surface tension) properties 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 been studied. A Gibbs–Van Ness type apparatus for total vapour pressure measurements was used to obtain vapour–liquid equilibria (VLE) data for methanol–TAME at 298.15 and 318.15 K. The system shows positive deviations from Raoult's law with an azeotrope. The surface tension, γ, for methanol–TAME and methanol–MTBE mixtures was measured at 298.15 and 308.15 K. Values for the relative surface adsorption calculated from the surface tension and the chemical potentials indicate that the surface is enriched in ether. The lattice-fluid, the lattice-fluid associated solution, and the extended real association solution models have been used to describe the bulk properties of the methanol–TAME mixtures. The model proposed by Rice and Teja has been used to describe the surface tension of the methanol–MTBE and methanol–TAME mixtures.