Abstract
The group contribution concept can be applied in the
estimation of thermodynamic properties of pure compounds and
mixtures. The Modified UNIFAC (Dortmund) is a successful and
well-known group contribution model for phase equilibria prediction.
In this paper the application of this model to the phase equilibrium of
biodiesel - volatile organic compounds systems was tested. Infinite
dilution activity coefficients of 30 selected volatile organic
compounds (VOCs) in methyl linoleate and methyl palmitate were
estimated. The VOCs groups covered in the selection were alkanes,
alkenes, alkynes, aromatics, ethers and ketones. The estimated phase
equilibrium is favourable for the absorption of these organics into
methyl linoleate. The solubility was found to decrease with increase
in molecular weight of the VOCs in each group. Saturation was also
found to have an effect on solubility. Experimental data are often not
available, at least for preliminary design and feasibility studies of
absorption processes, group contribution methods can be utilized to
predict the required phase equilibria.