PDF(Pubmed)
Abstract：
Amphiphilic fluorocarbon substances are a trending topic of research due to their wide range of applications accompanied by an alarming environmental and health impact. In order to predict their fate in the environment, use them more economically, develop new water treatment methods, etc., a better understanding of their physicochemical behavior is required. Their hydrophobicity in water/oil systems is particularly sensitive to one key thermodynamic parameter: the free energy of transfer of a perfluoromethylene group from oil to water. However, for the -CF2- moiety, the transfer energy values reported in the literature vary by more than ±25%. Due to the exponential relationship between this energy and the adsorption constants or the partition coefficients, such an uncertainty can lead to orders of magnitude error in the predicted distribution of fluorinated species. We address this problem by presenting an experimental determination of the hydrophobic effect of a -CF2- moiety with a greater certainty than currently available. The transfer energy is determined by measuring the interfacial tension of water|hexane for aqueous solutions of short-chained fluorotelomer alcohols. The obtained results for the free energy of transfer of a -CF2- moiety from oil to water are 1.68±0.02×RT0, 1.75±0.02×RT0, and 1.88±0.02×RT0 at 288.15 K, 293.15 K, and 303.15 K, respectively.
摘要：
两亲性碳氟化合物物质由于其广泛的应用伴随着令人震惊的环境和健康影响而成为研究的热门话题。为了预测他们在环境中的命运，更经济地使用它们，开发新的水处理方法，等。,需要更好地了解它们的物理化学行为。它们在水/油系统中的疏水性对一个关键的热力学参数特别敏感:全氟亚甲基从油转移到水的自由能。然而,对于-CF2-部分，文献中报道的转移能量值变化超过±25%。由于该能量与吸附常数或分配系数之间的指数关系，这种不确定性会导致氟化物质预测分布的数量级误差。我们通过提供比目前可用的更大的确定性的-CF2-部分的疏水作用的实验测定来解决这个问题。通过测量短链氟调聚物醇水溶液的水|己烷的界面张力来确定传递能。在288.15K时，-CF2-部分从油转移到水的自由能的结果为1.68±0.02×RT0，1.75±0.02×RT0和1.88±0.02×RT0，293.15K,和303.15K，分别。
