(Vapor + liquid) equilibrium for mixtures ethanol + biodiesel from soybean oil and frying oil

Abstract

In order to provide new isobaric vapor−liquid equilibrium (VLE) data for ethanol-biodiesel systems, experimental boiling points for mixtures of ethanol + biodiesel from soybean oil (SB) and frying oil (FB) were measured. UNIFAC and NRTL models were used to predict and correlate the data, in order to better represent the VLE in process simulation. VLE data were measured with a Fischer type ebulliometer. Reliability and reproducibility were evaluated with VLE data for ethanol + water system at 101.32 kPa. These data also proved to be thermodynamically consistent based on the area test. The boiling temperatures for ethanol + biodiesel systems agreed with other results reported at same pressure for SB and for biodiesel from sunflower seed oil (SSB). The thermodynamic modelling using the NRTL model obtained lower AAD values than those from UNIFAC, assuring better safety in the design and simulations steps of a biodiesel production plant.