Hydrotrope-Induced Enhancement of Room Temperature Surface Activity for High Krafft Point Fluorinated Surfactants

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• 作者：Hong-Tao Zhou ; Hang Xing ; Bo-Wan Wu ; An-Qing Cao…
• 关键词：Perfluorooctylsulfonate ; Fluorocarbon surfactant ; Sodium p ; toluenesulfonate ; Additive ; Hydrotropic agent
• 刊名：Journal of Surfactants and Detergents
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：19
• 期：6
• 页码：1199-1207
• 全文大小：639 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Industrial Chemistry and Chemical Engineering
  Surfaces and Interfaces and Thin Films
  Polymer Sciences
  Waste Water Technology, Water Pollution Control, Water Management and Aquatic Pollution
  Analytical Chemistry
  Physical Chemistry
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1558-9293
• 卷排序：19

文摘

Potassium perfluorooctane sulfonate (KPFOS) and sodium perfluorooctane sulfonate (NaPFOS) exhibit poor surface activities in aqueous solution at room temperature because of their high Krafft points. In this work, we attempted to increase the solubility of KPFOS and NaPFOS and consequently improve their surface activities at room temperature with sodium p-methylbenzene sulfonate (BS) and urea, which are typical hydrotropes in industrial applications. The effects of BS and urea on the surface tension of the aqueous solutions of KPFOS and NaPFOS were investigated at 25 °C. When the hydrotropes were added, the effectiveness of KPFOS and NaPFOS in surface tension reduction was greatly enhanced and KPFOS showed higher efficiency in surface tension reduction than NaPFOS. On the other hand, BS had much stronger ability than urea to reduce the surface tension of KPFOS and NaPFOS in water. In particular, with the assistance of BS the minimum surface tension of KPFOS approached 19 mN/m at 25 °C. It was worth noting that in the presence of BS, the surface tension of an apparently “saturated” solution (i.e., with coexisting surfactant solid) continuously decreased with increasing surfactant concentration. This behavior was ascribed to enrichment of branched PFOS isomers in aqueous phase with the assistance of BS, as evidenced by high-resolution 19F NMR. Hydrotropes were able to recover the inherent character of KPFOS and NaPFOS as highly surface-active fluorinated surfactants by increasing the solubility of branched isomers. This is an easy way to enhance the effectiveness in surface tension reduction at room temperature for fluorinated surfactants with high Krafft points.