Synthesis and characterization of a novel surfactant used for aqueous film-forming foam extinguishing agent

Abstract

Fluorocarbon surfactants are a key ingredient of aqueous film-forming foam (AFFF) extinguishing agent. As is well known, the most widely used fluorocarbon surfactants are perfluorooctane sulfonates (PFOS) and theirs derivatives. However, PFOS has been restricted due to its drawbacks such as toxicity, bio-accumulation and resistance to biodegradation, etc. Fortunately, the toxicity and bio-accumulation can be neglected if the fluorocarbon chain contained in the surfactants is less than or equal to 4. Therefore, synthesis of novel short fluorocarbon chain (≤ C4) surfactants has become a very important way to solve this problem. A novel fluorocarbon surfactant based on perfluorobutyl had been synthesized and its chemical structure had been confirmed by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR) and 19F NMR measurements in this work. Since the fluorocarbon surfactant mixed with appropriate hydrocarbon surfactant can reduce its dosage and cutting production costs, the surface tension and the critical micelle concentration (CMC) of the synthesized fluorocarbon surfactant and its equimolar mixtures with CH3(CH2)5NaO3S had been studied. The results show that CMC and the surface tension at CMC (γCMC) of the pure surfactant were 21.68 mmol/L and 17.08 mN/m, while the minimum surface tension and CMC could reach to 16.58 mN/m and 7.72 mmol/L for the mixed system, respectively. In addition, the foamability, spreadability and extinguishing performance of the equimolar mixed system has also been investigated. The foam expansion and the 25% drainage time are 9.8 and 313 s, respectively, and the extinguishing times are less than 65 s while the burnback times are more than 14.50 min for all the hydrocarbon oils studied in this work, indicating a great application prospect in AFFF.