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Author Topic: Would titanium make a good sunscreen?  (Read 1499 times)

Offline thedoc

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Would titanium make a good sunscreen?
« on: 13/06/2014 17:30:01 »
Erin asked the Naked Scientists:
   
I found your website listed at the bottom of an on-line article which discusses titanium dioxide, here: http://www.rsc.org/chemistryworld/podcast/CIIEcompounds/transcripts/titanium_dioxide.asp. I am interested in making a uv-protectant lotion and was considering either titanium dioxide or zinc oxide as the active ingredient. An excerpt from the article states, "It is perhaps ironic then that such a well known whitener should find its greatest cosmetic use in sunscreen - white is a shade sun worshippers are generally eager to shed! But here it is used for its so far unmatched ability to reflect, scatter and absorb harmful UV light - thus protecting the skin beneath it.

And this interaction with UV light leads to another valuable property - titanium dioxide is a photocatalyst. When it absorbs UV light, the energy causes reactive free radicals to be produced. In sunscreen, these must be captured by a layer of silica or alumina around the titanium dioxide particles because the radicals are potentially harmful to humans. But being a photocatalyst is a big bonus for many other applications, where these radicals can be put to good use." Would it therefore, be unsafe to simply add titanium dioxide to a lotion formula and call it "sunscreen" without adding silica or alumina to the recipe as well? I am hoping you or your colleagues may be able to share some of your expertise with me on this subject. Thank you so very much!

Erin Lee
What do you think?
« Last Edit: 13/06/2014 17:30:01 by _system »


 

Offline chiralSPO

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Re: Would titanium make a good sunscreen?
« Reply #1 on: 14/06/2014 00:45:35 »
You are correct that titanium dioxide does absorb and/or scatter UV light very well. One crystalline phase of TiO2 (anatase, as opposed to rutile, which is more common) is a photocatalyst which, when excited with the right frequency of UV light can catalyze oxidation reactions or generation of free radicals. I would agree that this is a very undesirable property for a sun lotion. Luckily, most of the TiO2 used in sun lotion (and as white pigments in everything from white paint to confectioner's sugar) is the significantly less active rutile form.
« Last Edit: 14/06/2014 00:49:55 by chiralSPO »
 

Offline lightarrow

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Re: Would titanium make a good sunscreen?
« Reply #2 on: 15/06/2014 19:02:05 »
If you use TiO2 you contributes to riduce the athmosphere pollution because your skin becomes a catalizer!  ;)

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Re: Would titanium make a good sunscreen?
« Reply #2 on: 15/06/2014 19:02:05 »

 

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