0,0 0,2 0,4 0,6 0,8 1,00

25

50

75

100

125

xC12OH

H (

kJ.

mol m

ixtu

re-1)

Solid-liquid phase diagrams of bynary mixtures formed by 1-octanol, 1-decanol, caprilic acid

and capric acidCastagnaro, T.S.1; Carareto, N.D.D. 1; Costa, M.C. 1;

Meirelles, A.J.A.ExTrAE, Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas

(UNICAMP) * E-mail: tomze@fea.unicamp.br

Acknowledgment

0,0 0,2 0,4 0,6 0,8 1,0

290

300

310

320

330

Tem

pera

ture

(K

)

xC12OH

L

L +

L+BB

OBJECTIVESThe study of phase equilibrium of lipid mixtures is an

important research subject connected to the food

industry, since many food products are based on fatty

systems. Nowadays, little research has concentrated on

the thermal behavior of fatty alcohols.

The aim of this study was to measure and model the

solid-liquid phase diagrams of the binary mixtures formed

by the following saturated fatty alcohol pairs: 1-octanol +

1-decanol, 1-decanol + 1-dodecanol, 1-dodecanol + 1-

hexadecanol and 1-tetradecanol + 1-octadecanol. The

liquidus line of these systems was modelled using the

Margules 3-Suffix and the NRTL equations.

EXPERIMENTAL SECTIONThe samples were prepared gravimetrically

(analytical balance -Adam AAA/L) with a ± 0.2 mg

accuracy. The melting temperatures and the

temperatures of solid-solid transition of pure fatty

alcohols and their mixtures were determined by DSC,

using a MDSC 2920, TA Instruments calorimeter under a

heating rate of 1 K.min-1. The calorimeter was equipped

with a cooling system, operated in the temperature range

of 218 K to 348 K and using nitrogen as a purge gas.

RESULTS AND DISCUSSIONIn thermograms some overlapped peaks are noted

and are attributted to other thermal events that can not

be identified using only DSC analysis. The phase diagrams

of the studied systems exhibit two inflection points in the

liquidus line related to the eutectic and peritectic

reactions (Fig.1).

The Tamman plot of the studied systems shows the

existence of a solid solution region in the extreme of the

phase diagram rich in the heaviest component (Fig.2).

CONCLUSIONThe DSC technique has proved to be an efficient and

reliable method for studying fatty alcohol mixtures. The

thermodynamic models Margules 3-suffix and NRTL allowed

for a good fit of the experimental data.

Fig. 1. Observed phase transitions of the system 1-dodecanol + 1-

octadecanol. ● fusion temperature; + temperature of solid-liquid

transition; ■ transition temperature under liquidus line; ● eutetic

reaction temperature; ■ temperature of solid-solid transition; ♦

transition on the solid phase of the pure component.

Fig. 2. Tamman plot for 1-dodecanol + 1-octadecanol system. ■

enthalpy of the eutectic reaction ● enthalpy of transition under

liquidus line.

EXTRAE

LABORATÓRIO DE EXTRAÇÃO,TERMODINÂMICA APLICADA E EQUILÍBRIO