Mentha arvensis IN OIL SOLID-LIQUID EQUILIBRIUM

ABSTRACT 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: ln(x) =#091;- 52.45 + 1,170.70/T + 8.48.ln(T) #093; 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.

摘要 L-薄荷醇（L-menthol）是提取自野薄荷（Mentha arvensis）的精油。本研究通过在悬浮液中加入过量晶体以制备指定温度下饱和溶液的方法，在271 K至300 K的温度区间内，测定了薄荷油组分中L-薄荷醇的固液平衡实验数据。将实验数据的摩尔分数取对数后，分别采用阿佩尔布拉特方程（Apelblat equation）和线性方程对温度T进行拟合，拟合效果良好，所得方程分别为：$ln(x) = -52.45 + frac{1170.70}{T} + 8.48ln(T)$ 与 $ln(x) = 3.98 - frac{1249.65}{T}$（式中T的单位为K）。上述两个方程均与实验数据具有良好的相关性。通过阿佩尔布拉特方程，还可将溶解焓计算为温度的线性函数，在所研究的温度区间内其平均值为150.31 J/mol。