Paloglou A, Martakidis K, Gavril D
Laboratory of Physical, Analytical and Environmental Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54636, Thessaloniki, Greece.
Laboratory of Physical, Analytical and Environmental Chemistry, Department of Chemistry, Aristotle University of Thessaloniki, 54636, Thessaloniki, Greece.
J Chromatogr A. 2017 Jan 13;1480:83-92. doi: 10.1016/j.chroma.2016.12.034. Epub 2016 Dec 14.
A novel methodology of reversed flow inverse gas chromatography (RF-IGC) is presented. It permits the simultaneous determination of mass transfer coefficients across the gas liquid interface as well as the respective solubility parameters and thermodynamic functions of dissolution of gases into liquids. The standard deviation of the experimentally determined parameters is estimated for first time, which combined with the successful comparison of the values of the present parameters with other literature ones ascertain the reliability of the methodology. Another novelty of the present work is that the chromatographic sampling of the physicochemical phenomena is done without performing the usual flow reversals procedure. Vinyl chloride monomer's (VCM) interaction with various composition liquid foods: orange juice, milk and olive oil was used as model system. The present transfer rates are controlled by the gas film at lower temperatures, but at higher temperatures the resistances in both films tend to become equal. The found liquid diffusivity values express the total mass transfer from the gas phase into the liquid's bulk and they decrease with rising temperature, as the solubilities of gases in liquids do. Solubility, expressed by Henry's law constant and the mean values of interfacial thickness are of the same order of magnitude to literature ones. From the thermodynamic point of view, VCM dissolution in all liquids is accompanied by significant heat release and it is a slightly non-spontaneous process, near equilibrium, while the entropy change values are negative.
本文提出了一种新型的逆流反相气相色谱法（RF-IGC）。它能够同时测定气液界面的传质系数以及气体在液体中的各自溶解度参数和溶解热力学函数。首次估算了实验测定参数的标准偏差，结合将当前参数值与其他文献值的成功比较，确定了该方法的可靠性。本研究的另一个新颖之处在于，对物理化学现象进行色谱采样时无需执行常规的流反转程序。以氯乙烯单体（VCM）与各种成分的液态食品（橙汁、牛奶和橄榄油）的相互作用作为模型体系。在较低温度下，当前的传质速率受气膜控制，但在较高温度下，两膜中的阻力趋于相等。所测得的液体扩散率值表示从气相到液体主体的总传质，并且它们随温度升高而降低，正如气体在液体中的溶解度一样。用亨利定律常数表示的溶解度和界面厚度的平均值与文献值处于同一数量级。从热力学角度来看，VCM在所有液体中的溶解都伴随着显著的热释放，并且它是一个接近平衡的略微非自发过程，而熵变值为负。
