Micellar Properties of a Foam Extinguishing Agent Based on Fluorocarbon Non-Ionic and Hydrocarbon Cationic Surfactants in a Mixed System

Fluorocarbon surfactant containing perfluorinated is the key component in aqueous film-forming foam extinguishing agent (AFFF), although its environmental concern is becoming more evident. In order to reduce the amount of this fluorinated surfactant while maintaining the micellar and surface properties, mixed systems based on fluorocarbon non-ionic and hydrocarbon cationic surfactants have received more attention with the aim of decreasing the environmental hazard of perfluorinated surfactants. The micellar properties, surface activity, and synergistic behavior of mixture systems of non-ionic fluorocarbon surfactant (undecafluoro-n-pentyl-decaoxyethylene ether (C۵F۱۱EO۱۰)) and three cationic surfactants with different alkyl chain (n-alkyltrimethylammonium bromides: ۱۰ (DTAB), ۱۴ (TTAB) and ۱۶ (CTAB)) are investigated. The effect of cationic chain length on physicochemical and thermodynamic properties are evaluated. Results obtained highlight a remarkable effect of reduction of the critical micellar concentration (CMC) with an increase in length of the chain; this effect is due to high the increase of hydrophobicity with the increase of the chain length. Furthermore, mixed system (C۱۰TAB-C۵F۱۱EO۱۰) has optimal synergy for minimizing surface tension. Also, the case of mixed micelles solutions rich on C۵F۱۱EO۱۰, CMC has less steric hindrance among hydrocarbons and fluorocarbons, which are more or less similar to carbon chains. Finally, the C۵F۱۱EO۱۰ suggests a synergy of CMC reduction with intermediate activity between C۱۶TAB-C۵F۱۱EO۱۰ and the C۱۰TAB- C۵F۱۱EO۱۰. Mixed systems (Foam) containing short-chain fluorotelomers tend to promote fewer toxic alternatives.

Keywords:

Fluorocarbon non-ionic surfactant , surface tension CMC , mixed system , synergistic behavior , foam property , theromdynamic models