The Complete Solution To Indoor Air Pollution
Analysis of what causes allergies and aggravated respiratory problems by the Center for Disease Control

PARTICULATES -- Dirt, Dust, Pollen, Spores , largest of the allergens. These
    allergens can be captured by a high-efficiency air filter.

BIOAEROSOLS -- Micro Organisms such as bacteria and mold. These allergens
    can be sterilized in the duct system by Second Wind air purifiers

VOLATILE ORGANIC COMPOUNDS -- Chemical gasses, solvents, and odor 
    causing contaminants. Neutralized in the duct system by Second Wind POC
    or singlet oxygen technology.

The Second Wind Family of air cleaners and air purifiers addresses every aspect of the Center for Disease Control Pie Chart. Particulate that are 3 micrometers and larger can be filtered out of the air through upgraded filtration. The Second Wind Inline Air Cleaner will help reduce particulates in the home substantially. Where the filtration stops, the Second Wind Air Purifier technology begins. Bioaerosols such as Microorganisms, Viruses, Mold, and Bacteria cannot be filtered out with standard filtration. The Second Wind Air Purifier with ultraviolet germicidal light sterilizes most
of this microscopic living organisms passing through the duct system. Volatile Organic Compounds are chemical gasses, solvents, and odor causing contaminants. The Second Wind Air Purifier will reduce the amount of these products in the air stream with it's POC and singlet oxygen technologies.

Photo-Catalytic Oxidation (PCO)
The Technology 

In order to fully understand PCO, we must first learn a little about the metal catalyst involved, Titanium in this case. Titanium has been stated as being a light, strong, and anti-corrosive. These characteristics are largely due to its unique, very thin barrier layer of oxidized film on its surface. This invisible surface layer, Titanium Oxide (Ti02), is quite remarkable in the fact that it will if scratched or damaged, immediately restore itself in the presence of air or water. The Ti02 film layer also has a high refraction ratio and when it is irradiated by UV light of less than 385nm, the band gap energy (the level of energy photons needed to be able to free electrons from their atomic bonds) is exceeded. What is created are electron/hole pairs, hydroxyl radicals (OH), thus attracting molecules, i.e. volatile organic compounds and bioaerosols, to the catalyst Titanium. The contaminants are oxidized by the reaction that takes place during the process due to the fact that the OH radicals need to attach themselves to something, and when they do they oxidize it to C02 and H20 primarily. 

                                Diagram of the POC Process

A good analogy to think of when you are pondering the concept is electronic air cleaners. Electronic air cleaners work by charging the large dust particles passing through them with an electronic charge, either positive or negative. The particles are than collected on oppositely charged metal plates. With PCO, after the VOC's and bioaerosols are attracted to the titanium, they are come into contact with the OH radicals which change the contaminants molecular structure. PCO will kill and decompose absorbed bioaerosols, as well as toxic VOC's and the odors they produce.

As can be seen from these charts the oxidation power of OH radicals is second only to that of fluorine. Looking at the oxidation power of ozone we can determine that it is not as powerful an oxidant as singlet oxygen or OH radicals. Therefore an ozone generator, though a good method of oxidizing VOC's, is not as effective as singlet oxygen 1.78 or OH radicals 2.06 in oxidizing contaminants. 

Advantages of Photo-Catalytic Oxidation 

Now that PCO technology can be integrated into new and existing heating, air conditioning, and ventilating systems everyone (even the most chemically sensitive) have an effect process for removing and destroying low-level indoor air pollutants including mold, bacteria, viruses, and fungi. 

There have been numerous scientific studies, research and applications using PCO technology. The following are a few exerts from some: 

"One effective method to destroy dilute concentrations of organic and chlorinated organic pollutants in air is heterogeneous POC, which uses a semiconductor catalyst such as Ti02 and near-UV radiation to decompose contaminants..." The large number and variety of chemicals successfully treated by PCO indicates potentially broad range of application."
John L. Falconer, Ph.D. Professor of Chemical Engineering Univ. of Colorado, Ph.D (Chemical Engineering), Stanford University 1974, B.E.S. (Chemical Engineering), The John Hopkins University, (1967)

"Photocatalysts for the destruction of indoor air pollutants, including VOC's and gaseous inorganic pollutants such as nitrous oxides, carbon monoxide, and hydrogen cyanide..." (Heller 1996). "Report test show the technology capable of rapidly destroying toxic components of tobacco smoke such as formaldehyde, acrolein and benzene."
Taken from the American Lung Association webpage January 24, 2001

"...The PCO technique destroys pollutants in both air and water..."
NREL National Renewable Energy Laboratory 

"...Carbon 13 labeled ethanol (CH3(13)CH20H) was absorbed on the catalyst and photocatalytically oxidized..."
Darrin S. Muggli; Sheldon A. Larson; John L. Falconer Journal of Chemistry 1996 

"...The purpose of this study is to investigate the purification of air emissions contaminated with toluene via the heterogeneous photocatalytic oxidation (PCO) process..." "...Experimental results indicated that near to 100% conversion ration of toluene are achieved for the initial 30-minute reaction period..."
Chung-Hsuang Hung Photocatalytic Decomposition of Toluene Under Various  volatile organic compounds temperatures.

"...Photocatalytic oxidation (PCO), a relatively new technology, shows promise for economically controlling hazardous air pollutants and volatile organic compounds from smaller sources, such as waste water treatment plants, dry cleaning facilities, painting facilities, carbon regeneration plants, air-stripping towers, soil venting processes, hazardous waste incinerators, and municipal landfills..."
Melanie Louise Sattler, Method for Predicting Photocatalytic Oxidation Rates of Organic Compounds

"...Potential applications for using titania-based materials as photocatalysts include...Destroying volatile organic compounds (trichloroethylene, benzene, formaldehyde, etc.). Reducing air pollution in homes and industries such as dry-cleaners, painting booths, and printers..." 
Marc A Anderson, Professor Water Chemistry Program and Material Science, University of Wisconsin 

"...In addition to automobile exhaust cleaning, use of environmental catalysts such as titanium oxide photocatalysts is rapidly growing for control of residential environments, e.g., antimicrobial activity and odor control..."
Katsunori Yogo, Masamichi Ishikawa, Interdisciplinary Department, Frontier Science Institute, Mitsubushi Research Institute, Inc.

"...Titanium dioxide is therefore applied for deodorizing, by decomposing substances causing bad odor, and for prevention of air pollution by absorbing and oxidizing..."
Japan Chemical Week, August 26, 1999 

Those are just a few examples of the vast research that has been and is being done on PCO technology, including Second Wind's own testing recently completed at the IAQ labs of the University at Waterloo on our own photocatalytic air purifiers. Please view the dramatic results of our testing on the following page.


   

All of the information on these pages can be obtained for more in depth study. All references and test data are available on request.

COMPARATIVE SUMMARY OF
AIR CLEANING TECHNOLOGY