Odor eliminating spiral compact fluorescents

A Chink in the Armor?

One concern raised about the use of TiO2 is the formation of potentially harmful intermediate products during the breakdown of organic substances. The 1979 report Bioassay of Titanium Dioxide for Possible Carcinogenicity NTIS# PB288780/AS (CAS No. 13463-67-7) states that TiO2 itself shows no evidence of carcinogenicity. But Carl Koval, a chemist at the University of Colorado in Boulder, and others have raised the concern that the reactions produced by TiO2 may create substances more dangerous than the original pollutant.

Says Koval, "When illuminated TiO2 is used to decompose organic compounds, a large number of intermediate compounds are usually formed. In some cases, these intermediate compounds can be more hazardous than the compound being decomposed." For example, he says, the breakdown of TCE yields trichloroacetic acid (a substance almost as toxic as TCE) and, in the gaseous phase, phosgene (a chemical warfare agent). However, he says, this doesn't mean that all applications using TiO2 would be dangerous. "In situations where this type of process was being proposed for outdoor use, I see no problems with it, because similar things occur naturally in the atmosphere, and it would be unlikely that concentrations of the hazardous chemical would reach toxic levels. . . . However, [in an indoor setting] who knows what would be formed if TiO2 photocatalysis were used to decompose plasticizers, bacteria, and so on, and what the health effects might be from inhaling such compounds?"

Certainly there is cause for caution, agrees Anderson. "But given time and control over the process," he adds, "these daughter products do break down into environmentally benign substances, a process which can be monitored using a gas chromatograph." And, says Blake, "All oxidization processes have the potential to produce partial oxidization products. It comes down to a question of the fraction of the target compounds that are converted to the intermediate products and how much of those produced are released into the air or water. The amount released will be a function of the efficiency of the photocatalytic device and the way it is constructed and operated."

All that being said, in the realm of environmental cleanup technology is TiO2 indeed the white knight riding to the rescue or something less? Says Blake, "There is no single technology that can address the very wide range of contamination problems in the environment. Most workers in the field recognize that the photocatalytic chemistry of TiO2 has pluses and minuses that make it attractive for some applications and not for others. The photocatalytic chemistry of TiO2 is very intriguing. It works in water or air, it uses light instead of heat, and it is such a simple concept. Engineering it with the right balance of economics and performance is the challenge."

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SoloGro57 said:

I own one, It may work in certain situations (pet odors maybe?) but in no way should u trust these products to keep your indoor grow stealthy

The reason I say this is because if you are on a tight budget and you find yourself needing to buy a fan and carbon filter in a hurry, like I did, you may find your security compromised.

It sounded too good to be true to me too, and it was.

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noreason said:

red laser….maybe I'm wrong, but I'm talking about photocatalysis and TiO2 (UV-a is enough energy for the Ti band gap) and you're talking about O3 (and UV-c)…they're different things.

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