Mentha arvensis IN OIL SOLID-LIQUID EQUILIBRIUM

L-menthol is an essential oil produced from Mentha arvensis. An experimental L-menthol solid-liquid equilibrium in menthol oil constituents was determined in the temperature range between 271 K and 300 K, by the method of creating a saturated solution at a given temperature by using an excess of crystals in the suspension. The mole fraction of the experimental data, on a logarithmic basis, were fitted against T by the Apelblat equation and by a linear equation with good results. The equations were: In(x) =[- 52.45 + 1,170.70/T + 8.48.ln(T)] and ln(x) = 3.98 -1,249.65/T with T in K. Both equations give a good correlation with the experimental data. From the Apelblat equation the enthalpy of solution was also calculated as a linear function of temperature and has an average value of 150.31 J/mol in the temperature interval studied.