Efficiency Enhancement of Class-A Foams with Nanoparticles to Fight Wildfires

Lead Researcher: Dr Mauro S. Innocente
Researchers:
Ioannis Papagiannis
Dr Evangelos Gkanas
Prof Guillermo Rein (and HazeLab)
Partners:
Pau Costa Foundation (contact: Jordi Vendrell)

Funder: LRF International Consortium of Nanotechnologies
fEC: £100,000 (£50,000 award + £50,000 match funding).
Link 1, Link 2

Project title: Efficiency Enhancement of Class-A Foams by Means of Nanoparticles for Self-Organising Swarms of Autonomous UAVs to Fight Wildfires

Synthesis and Characterisation of Iron Oxide Nanoparticles with Tunable Sizes by Hydrothermal Method

The study on the effect of different reaction times on the size and surface morphology of iron oxide nanoparticles is described. In this synthetic system, aqueous iron (III) nitrate (Fe(NO₃)₃·9H₂O) nonahydrate, provided the iron source and triethylamine was the precipitant and alkaline agent. By prolonging the reaction time from 3 h to 24 h the evolution process changed from elongated rod-shaped nanoparticles to finally distorted nanocubes. The as-synthesised iron oxide nanoparticles have been characterised by X-ray diffraction (XRD), Rietveld analysis, Scanning Electron Microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Analysis on crystallinity of the iron oxide nanoparticles suggest that the samples mainly consist of two phases which are Goethite (α-FeOOH) and Hematite (α-Fe₂O₃) respectively.

Effects of Iron Oxide Nanoparticles on Class A Foam Stability

Nanotechnology is a rapidly emerging technology with many promising applications, and one area where it is constantly advancing is fire protection. In order to effectively prevent the fire, firefighting foams with high stability are of the essence. High stability corresponds to slow foam drainage thus a longer lasting foam that can significantly affect the transportation and application of the product to the fire incident. However, based on the poor foam stability, nanoscale additives can reduce the degradation of the foam solution and make it withstand higher temperatures due to their unique properties such as high adhesion energy to the interface between air and liquid. The current work is focused on the understanding of the potential synergistic effect of Iron Oxide Nanoparticles (IONPs) with Class A foams and its effect on the foaming and foam stability of the dispersions. The dynamic changes of surface tension, particle size distribution and ζ potential values of IONPs/foam aqueous dispersions were systematically studied to elucidate the stabilization mechanism of the nanoparticles in foam. Traditional foam experiments were carried out, focusing on the influence of stirring intensity and concentration on the stability characteristics of IONPs in foams. The IONPs dispersion into the foam was prepared by dispersing a certain mass at different concentrations (0.05 wt%, 0.1 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt% 2.0 wt%, 5.0 wt%) and compared to the properties of the pure foam. Furthermore, superficial morphology images of the IONPs/foam via a digital microscope were compared to the conventional one to assess the new mixture’s surface morphology. Cryo-SEM analysis of frozen foams has been used to identify the nanoparticles distribution inside the foam, in which they were concentrated on the bubble surfaces. Finally, foam stability was enhanced by the adsorption of the nanoparticles at the interface of Class A foams, thus reducing foam drainage and bubble coalescence compared to off-the-shelf foams. The obtained results may expedite the development of a long-term stable foam that can provide longer duration and resistivity to higher temperatures with ultimate application in enhanced fire extinguishment. Future goals of the project will be to carry out small-scale fire experiments on the conventional foams, and performance will be compared against that achieved by the enhanced foams with nanoparticles.