Nanoporous Metal Foams as Efficient Particulate Filters

Nanostructured metal foams offer exciting potential for applications in diverse fields such as catalysts, electronics, heat exchange, structural materials, and filtration due to their extremely high surface area to volume ratios. We have achieved a variety of metallic foams using electrochemical methods, with strong mechanical stability and tunable porosity and density (0.1%-30% of bulk density) [1]. Uniaxial compression tests reveal significantly varying structural strengths depending on the relative density. Additional physical characteristics and applications have been explored. We have also investigated using such foams as efficient filtration membranes for micron and sub-micron sized particles. Over 99% of airborne micron sized particles are found to be filtered after passing through just 1 mm of metallic foam. The foams are also found to be effective for filtering out deep submicron particles. The pressure drops across the foams are found to vary depending on the bulk density of the foam; with the lower density foams being comparable to commercial HEPA filters.

[1] D. A. Gilbert, et al, Chem. Mater. 29, 9814 (2017).