Huan Li,Xiaoyang Yu,Ke Qiu,Bing Bo,Qian Li,Shouxiang Lu
The active ingredients for aqueous film-forming foam (AFFF) are supplied as a concentrate, and the water used to dilute AFFF concentrates generally come from water sources around the fire site including seawater and river water. However, the effects of salt in water on fire-extinguishing performance of AFFF remain unclear. In this paper, we investigated the relationship between the interfacial properties, foam stability, and fire-extinguishing performance of three homemade AFFFs (nonionic AFFF APG , amphoteric AFFF CAB and anionic AFFF SDS ) and four commercial AFFFs. The seawater, firefighting water from different regions of China and deionized water were used to dilute AFFF concentrates. The results showed that AFFF APG and AFFF CAB had a better performance than AFFF SDS in resisting the negative effects of salts on interfacial properties and foaming ability. In the fire-extinguishing tests, we found that dilution of AFFF with water samples containing high concentrations of Ca 2+ and Mg 2+ would weaken the fire-extinguishing performance. The traditional indicators characterizing the properties of foam (surface tension, liquid drainage rate, and spreading coefficient) could not explain the trend of fire extinguishing performance. The stability of AFFF in the presence of oil could be used to explain the difference in fire-extinguishing time of AFFF.
Preparing fluorocarbon surfactant for aqueous film-forming foam is a complex process. Overcoming steric hindrance when introducing imidazolium to the fluorocarbon chain is a key challenge. In this significant work, we proposed a simple one-step route to prepare imidazolium-contained fluorocarbon surfactant under mild conditions. The FT-IR, 1H NMR, 13C NMR, MS, and TG technologies characterized the imidazolium-contained fluorocarbon surfactant by analyzing functional groups, molecular weight, and thermal stability. An equimolar mixture of imidazolium-contained fluorocarbon surfactant and C6H13NaO3S demonstrated high surface activity, enabling the foam to spread effectively on commercial fuels. The spreading coefficient of foam on n-cyclohexane met the US Military Specification. Coordinatively, the foam drained in time to maintain the stability and completeness of the aqueous layer, with a moderate 25% drainage time of 317 s and a proper foam expansion ratio of 10.5. In extinguishing experiments, the imidazolium-contained fluorocarbon surfactant/C6H13NaO3 mixture extinguished test fires in 65 s, suggesting an essential potential in the aqueous film-forming foam formula.
A fluorinated surfactant exhibits extremely high surface activity and is the key component of the aqueous film-forming foam (AFFF) extinguishing agent. Unfortunately, the long fluorinated carbon chain has been proven to be bioaccumulative and has been banned internationally. This study aims to design and synthesize Y-shaped surfactants based on short fluorocarbon chains through atom transfer radical addition (ATRA), while maintaining the excellent performance as that with a long fluorocarbon chain. A minimum surface tension of 13.5 mN/m for (FC6HC6)2-CHOSO3Na can be reached with even a quite low concentration (0.04 g/L) according to a surface activity test, satisfying the performance requirements of the surfactant used for AFFF extinguishing agent. Moreover, the aqueous solution on the oil spreads out rapidly (<0.5 s), with a large spreading area of 2.89 cm2. In addition, an AFFF extinguishing agent formula based on the synthesized fluorinated surfactant is successfully obtained, whose foam production fulfills the requirements of the national standard of a fire-extinguishing agent (GB 15308-2006). In subsequent fire extinguishing tests, this extinguishing agent behaves successfully. To sum up, the Y-type surfactant is a degradable surfactant, which can be used as an AFFF extinguishing agent with excellent performance, highly promising in practical application.
危险品化学品经营许可证（带存储）