Standal SH, Blokhus AM, Haavik J, Skauge A, Barth T
Department of Chemistry, University of Bergen, Allègaten 41, Bergen, N-5007, Norway
J Colloid Interface Sci. 1999 Apr 1;212(1):33-41. doi: 10.1006/jcis.1998.5988.
Partition coefficients, surface tension, and interfacial tension for some polar organic components dissolved in oil/water model systems have been investigated. The systems consist of isooctane modeling the oil phase and of water solutions of NaCl and CaCl2 modeling the water phase. The organic compounds examined were 1-naphtoic acid, 5-indanol, and quinoline, all well-defined molecules known to be representative of polar components in crude oil. The dependence on pH, salinity, and ionic strength in the water phase was investigated. The surface tension and interfacial tension were also examined as a function of component concentration. The results show a connection between the distribution of the polar components and the interfacial tension. Correspondence between the partition coefficient and the pKa value for the components is also reported. For 1-naphtoic acid none of the two ionization forms of the molecule are found to be surface active in aqueous solution. For 5-indanol both forms are surface active, and for quinoline only the nonionic form of the molecule is found to be surface active. The results indicate that the aqueous phase is the one that governs the interfacial tension. Increasing salinity increases the concentration of the component in the oil phase and decreases the interfacial tension between the oil phase and the aqueous phase. The results are explained due to the "salting-out" effect and to changes in the electrostatics for the various systems. Copyright 1999 Academic Press.
研究了溶解在油/水模型体系中的一些极性有机组分的分配系数、表面张力和界面张力。该体系由模拟油相的异辛烷和模拟水相的NaCl及CaCl2水溶液组成。所研究的有机化合物为1-萘甲酸、5-茚醇和喹啉，这些都是明确的分子，已知是原油中极性组分的代表。研究了其对水相pH值、盐度和离子强度的依赖性。还研究了表面张力和界面张力随组分浓度的变化。结果表明极性组分的分布与界面张力之间存在联系。还报道了各组分的分配系数与pKa值之间的对应关系。对于1-萘甲酸，该分子的两种电离形式在水溶液中均无表面活性。对于5-茚醇，两种形式均有表面活性，而对于喹啉，仅发现该分子的非离子形式有表面活性。结果表明水相是控制界面张力的相。盐度增加会使油相中组分的浓度增加，并降低油相和水相之间的界面张力。这些结果可通过“盐析”效应和各体系静电作用的变化来解释。版权所有1999年学术出版社。
