水+油+CiPj三成份系統之相行為及濕透行為研究

Abstract

在本研究中針對水+油+非離子型界面活性劑三成份系統探討其相行為及濕透行為，所使用的油皆為正烷類，非離子型界面活性劑為CiPj。CiPj為醇醚類化合物，是CH3(CH2)i-1(OCH2CH(CH3))jOH之縮寫，其中i代表非極性碳氫鏈長度，而j代表的是丙烯氧基的長度。我們在水+正十烷+C3P1、水+正十二烷+C3P1、水+正十四烷+C3P1、水+正十六烷+C3P1、水+正十二烷+C3P2、水+正十四烷+C3P2及水+正十六烷+C3P2七個系統中，發現三液相共存區的存在。配製水與油的重量比為1:1的水+油+CiPj三成分溶液，透過改變CiPj的重量分率及溫度，觀察系統平衡時的液相數目，可將結果繪製成魚形相圖。透過比較七個系統的魚形相圖，可以清楚地知道當油的碳數增加時，三液相共存區的上、下臨界溫度都會上升；另外增加CiPj中j的數目，則會使上、下臨界溫度下降。接著我們使用氣相層析儀，對水+正十二烷+C3P1、水+正十四烷+C3P1、水+正十六烷+C3P1、水+正十二烷+C3P2、水+正十四烷+C3P2及水+正十六烷+C3P2六個系統在進行液-液相平衡量測，並將結果繪製成三角相圖。根據相圖的結果，在水+油+CiPj三成分系統中，隨著溫度的上升，可以觀察到從兩液相轉變為三液相再轉變成兩液相的相行為，其中低溫時的兩液相，下層相的界面活性劑重量分率較上層相高，高溫時的兩液相則是相反的情況，此現象和文獻中水+油+非離子型界面活性劑的相行為相符。此外，我們利用NRTL模型對各系統三角相圖的數據結果進行迴歸分析及理論計算，發現NRTL模型可有效地描述水+油+CiPj三成分系統的相行為。對一三液相系統，可藉由測量上層相對中間相、上層相對下層相及中間相對下層相三種界面張力，判斷其濕透行為。在本研究中，利用懸垂液滴法測量界面張力，輔以觀察法，對水+正十二烷+C3P1、水+正十四烷+C3P1、水+正十六烷+C3P1及水+正十六烷+C3P2四個系統探討其濕透行為，發現這四個系統在三液相的溫度區間，都是呈現中間相的完全濕透行為。

In this study, we investigate the phase behavior and the wetting behavior of the ternary water + oil + nonionic surfactant system. The oils are n-alkanes and the nonionic surfactants are CiPj. The symbol CiPj is the abbreviation of a propylene glycol ether CH3(CH2)i-1(OCH2CH(CH3))jOH. There are three-liquid-phase- coexisting regions in water + decane + C3P1, water + dodecane + C3P1, water + tetradecane + C3P1, water + hexadecane + C3P1, water + dodecane + C3P2, water + tetradecane + C3P2, and water + hexadecane + C3P2 systems. Experiments of fish-shaped phase diagrams for these seven systems under atmospheric pressure were performed at constant water/n-alkane weight ratio (1/1) to locate the critical end points. The ternary system of the alkane with the longer carbon chain length has the higher upper and lower critical solution temperatures and the larger three-liquid-coexisting temperature window in the fish-shaped phase diagram. The upper and lower critical solution temperatures are lower in these systems with larger j number of C3Pj. Precise liquid-liquid equilibrium data of mixtures for six ternary systems water + alkane (dodecane, tetradencane, and hexadecane) + C3Pj (j=1 or 2) under atmospheric pressure were determined by using gas chromatography. The evolution of phase behavior of the ternary water + n-alkane + C3Pj system as a function of temperature is qualitatively consistent with that of the water + oil + CiEj system. The experimental liquid-liquid equilibrium data were successfully correlated with the NRTL model. We use pedant drop method to measure the interfacial tensions and investigate the wetting behavior of four ternary systems, water + dodecane + C3P1, water + tetradecane + C3P1, water + hexadecane + C3P1, and water + hexadecane + C3P2 system. In these ternary systems, the middle surfactant-rich phase exhibits complete wetting in the temperature window of the three-liquid-phase-coexisting region.