无机纳米颗粒对无氟泡沫灭火剂稳定性影响机制研究

Nanoparticles show better ability to stabilize bubble than traditional foam stabilizers, and has a promising application in the development of environmental-friendly fluorine-free fire-fighting foam. But the influence mechanism of nanoparticles on the stability of fire-fighting foam is still not well understood. In this project, fire-fighting foams with inorganic nanoparticles (NP-Fire-fighting foam) are prepared based on the mixture of inorganic nanoparticle with fluorine-free fire-fighting foam. The experiments for evaluating stability of NP-Fire-fighting foam are conducted. The effect of inorganic nanoparticles on drainage and coarsening of fire-fighting foam is systematically studied. Evaporation loss, drainage, coarsening, attenuation characteristics of NP-Fire-fighting foam and temperature distribution in foam under the action of heat are deeply studied. The two key scientific questions, mechanism of action of inorganic nanoparticles on the stability of aqueous film of foam, and the attenuation mechanism of NP-Fire-fighting foam under the action of heat, are solved based on the results of experiments and the theories related to surfactant, surface chemistry, physical chemistry, and heat and mass transfer. The effect law of inorganic nanoparticles on fire-fighting foam stability is determined. The synergetic mechanism of inorganic nanoparticles and surfactants in fire-fighting foam on foam stability is uncovered. The effect mechanism of inorganic nanoparticles on fluorine-free fire-fighting foam stability under the action of heat is clarified. The results obtained in this project can enrich and improve the theory related to foam stabilized by nanoparticles, and provide theoretical support for the development of new environmental-friendly fire-fighting foam used to liquid fuel fire.

纳米颗粒具有比传统稳泡剂更高的稳泡效能，在开发无氟环保型泡沫灭火剂方面具有良好的前景，但纳米颗粒对泡沫灭火剂稳定性影响机制尚缺乏系统认识。本项目采用无机纳米颗粒与无氟泡沫灭火剂复合制备包含无机纳米颗粒的泡沫灭火剂（NP-泡沫灭火剂），开展泡沫稳定性实验，系统研究无机纳米颗粒对泡沫灭火剂析液和粗化的影响，定量研究热作用下NP-泡沫灭火剂蒸发、析液、粗化、衰减规律及泡沫层温度分布特征；结合表面活性剂理论、表面化学理论、物理化学理论及传热传质理论，解决无机纳米颗粒对泡沫液膜稳定性的作用机制和热作用下NP-泡沫灭火剂衰减机制两个关键科学问题，探明无机纳米颗粒对无氟泡沫灭火剂稳定性的影响规律，揭示无机纳米颗粒与泡沫灭火剂活性组分协同稳泡机理，阐明热作用下无机纳米颗粒对无氟泡沫灭火剂稳定性的影响机制。研究成果将丰富和完善纳米颗粒稳泡理论，为开发新一代环保型液体火灾泡沫灭火剂提供理论支撑。

水成膜泡沫（aqueous film-forming foam, AFFF）是一类用于扑灭液体火灾的泡沫灭火剂，凭借在液体燃料表面形成水膜层和泡沫层，实现高效灭火。然而，AFFF核心组分长链氟碳表面活性剂(C8-C10)存在严重的环境问题，已被限制使用。开发适用于液体火灾的新一代环保型泡沫灭火剂是消防领域面临的迫切任务。纳米颗粒被证明具有良好的稳泡能力，在开发环保型泡沫灭火剂方面具有良好的前景，然而关于纳米颗粒对泡沫灭火剂影响的研究很少，很多科学问题仍不清楚。为此，本课题致力于探究纳米颗粒对环保型泡沫灭火剂稳定性影响机制。. 首先，研究了泡沫稳定性随纳米颗粒种类、比表面积、浓度变化的规律。研究结果表明SiO2与Al(OH)3具有极好的稳定泡沫的能力，其中SiO2在比表面积为300m2/g时具有最佳稳泡性能。整体上，随着NP浓度的增加，复配体系的泡沫稳定性也随之增加，这是因为NP会在液膜和Plateau边界聚集，形成稳定的网络结构，有效地延缓泡沫析液和粗化，增强泡沫的稳定性。然而过高的NP浓度会导致复配体系起泡性能减弱，因此针对不同的泡沫组分，NP浓度需要控制在3%-10%。. 其次，研究了NP与表面活性剂在泡沫液膜及气/液界面上的协同作用规律；揭示了无机NP与表面活性剂协同稳泡机理。研究结果表明NP与泡沫灭火剂活性组分在溶液中会发生强烈相互作用。NP种类、浓度、比表面积对相互作用有显著影响。这些相互作用使得NP与泡沫灭火剂活性组分在液膜和Plateau边界处相互吸附或交联，从而延缓泡沫析液与泡沫粗化，极大提高泡沫稳定性。. 最后，基于自建实验平台，开展了热作用下不同种类、浓度、比表面积、晶型的NP对泡沫蒸发、析液、粗化及泡沫总高度随时间变化规律及泡沫层温度分布特征，阐明了纳米颗粒对泡沫热稳定影响机制。研究发现，高温下泡沫快速析液、粗化和蒸发而破裂，NP的存在延缓了析液和粗化，减少了泡沫层中的热量传递，从而显著提升泡沫灭火剂的热稳定性。本项目研究结果能够为NP在环保型泡沫灭火剂中的应用提供理论依据。