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I always hear that some big corporations use "diamond dust" to filter water seven times to make "diamond clear" vodka. I tried googling something about using diamonds for filtering, but I could not find anything except corporate sites that tell us only the best things about "diamond dust filtration technology".
Is this just a bogus claim? Because I can not think about diamonds as a viable filtering material.
It appears that there is some validity to this technology. Not surprisingly, the published journal literature available is basically non-existent, except for a handful of patent applications describing something along those lines.
The title of one journal publication "Preparation of a filtering material using nanomaterials for removal of a heavy metals from wastewater" uses a diamond nanopowder to aid in filtering out heavy metals from waste water. The citation is "Antonenko, L. P., Energotekhnologii i Resursosberezhenie, 6, 2011, 49-54"
Additionally, there is a patent appplication from France (where at least one article I read cited as the technology originating from), title "Apparatus for activation and mineralization of water for domestic use". In this, they use a variety of powdered gemstones (diamond, ruby, sapphire) as well as precious metals (gold, silver) to filter the water.
Certainly, nano-particle scale materials are effective filtration agents, as most contaminants will not pass through such a small sized filtration device. The use of some gemstones (certainly diamond) are beneficial for their relative chemical inertness, and certainly silver is well-known for it's antimicrobial activity, and synthesis of gold-nanoparticles or gold-silver coatings are also actively under research
Altered properties (band gap, Stokes shift) of cristalline nanoparticles as compared to bulk have been demonstated for various semiconductors, namely CdS, CdSe, TiO2, etc. They result from a significantly different surface-to-volume ratio and the fact that atoms at the crystal surfaces simply lack the proper number of neighbours.
Where the crystal ends, the is just no other neighbour. Since there's less than normal neighbours, centres at the surface are more reactive.
As far as the properties of the diamond dust are concerned, i do however remain skeptic and to me, the whole thing mostly sounds like marketing lingo.
The term diamond dust suggests something valuable: if the manufacturer uses something as precious as diamonds for filtering, the product must be valuable too.
But why would one actually want to use something with a rather inert diamond lattice of sp3-carbon atoms instead of microporous activated carbon with well-known adsorption properties?
Yes, diamond filters are used. Usually in the filtration of ethanol and water (vodka). All drinkable ethanol must be filtered through specialized carbon filters. So in the thinking that diamonds are formed from compressed carbon, therefore a diamond filter is the extreme sports of filtration. Whether it's better? I don't know, but it is a great marketing tool.
