Abstract
The combination of nanoparticles (NP) and surfactant has been intensively studied to improve the thermal stability and optimize the performance of foams. This study focuses on the influence of silica NPs with different concentration on the thermal stability of gel foams based on a mixture of fluorocarbon (FS-50) and hydrocarbon (APG0810) surfactants. The surface activity, conductivity, viscosity, and foaming ability of the APG0810/FS-50/NPs dispersions are characterized. The effects of NP concentration on coarsening, drainage, and decay, as well as of the gel foams under thermal action, are systematically studied. Results show that NP concentration has a significant effect on the molecular interactions of the APG0810/FS-50/NP dispersions. The surface tension and conductivity of the dispersions decrease but the viscosity increases with the increase in NP concentration. The foaming ability of APG0810/FS-50 solution is reduced by the addition of NPs and decreases with the increase in NP concentration. The coarsening, drainage, and decay of the gel foams under thermal action slow down significantly with increasing NP concentration. The thermal stability of the gel foams increases with the addition of NPs and further increases with the increase in NP concentration. This study provides a theoretical guidance for the application for gel foams containing NPs and surfactants in fire-extinguishing agents.
Highlights
Aqueous film-forming foam (AFFF) is currently recognized as the most widely used extinguishing agent in liquid fuel fires, as it has excellent foam stability and filmforming ability provided by fluorocarbon surfactants and hydrocarbon surfactants [12–16]
The higher temperature results in the faster increase in bubble size and disappearance. These results indicate that the addition of NPs significantly delays the foam coarsening under heat
The thermal stability of the foams stabilized by NPs, FS-50, and APG0810 were investigated systematically
Summary
Aqueous foam is a disperse form of gas in a continuous liquid [1]. Foam is widely used in food [2], foam flotation [3], firefighting [4,5], and petroleum industries [6–8] because of its high fluidity, excellent rheology, low water consumption, and reduced formation damage [9–11]. Aqueous film-forming foam (AFFF) is currently recognized as the most widely used extinguishing agent in liquid fuel fires, as it has excellent foam stability and filmforming ability provided by fluorocarbon surfactants and hydrocarbon surfactants [12–16]. In the past few years, researchers have developed a series of environmentally friendly foam fire extinguishing agents by replacing long-chain fluorocarbon surfactants (C8–C10). Most of the current studies have just focused on the foam stability of NPs with a single surfactant. Few study focuses on nanoparticle-stabilized foams under high temperature. Considerable works need to be conducted to investigate the effect of NPs on foam thermal stability of multi-component surfactants. The effect of different concentrations of NPs on foam coarsening of the mixed dispersions at different temperatures is analyzed deeply. The results of this work provide a theoretical foundation for the application of NPs in firefighting foams
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