PHOTO-CATALYTIC OXIDATION CHAMBER
The ZAND-AIR PCOC™3 model is a powder-coated metal encased unit to be fitted into the HVAC/AHU unit or the air ducting to provide an airtight flow of the airstream through the unit and has the spaces for an optional removable MERV-13 and optional removable Activated Charcoal Filter. This model consists of three chambers, each with photocatalytic grids to provide additional dwelling time for maximum breakup of the molecular structure of the VOCs passing in the airstream.
The ZAND-AIR PCOC™3 uses PHOTO-CATALYTIC OXIDIZING (PCO) technology and converts and neutralizes Volatile Organic Compounds (VOC), odors, fumes, and toxic chemicals to benign water and carbon dioxide by-products. The process is called heterogeneous photocatalysis or photocatalytic oxidation.
The ZAND-AIR PCOC™3 model carries an additional slot for an Activated Charcoal Filter (ACF) to absorb aldehydes remaining in the airflow. This optional ACF filter with 1.5 kg of Activated Charcoal is specially formulated to adsorb any ambient formaldehyde / aldehydes. This ACF filter can be ordered on demand for this feature.
In chemistry, photocatalysis is the acceleration of a photoreaction in the presence of a catalyst. In catalyzed photolysis, light is absorbed by a catalytic substrate. In photo-generated catalysis the photocatalytic activity (PCA) depends on the ability of the catalyst to create electron-hole pairs, which generate free radicals (hydroxyl radicals: •HO) able to undergo secondary reactions. •HO is a diatomic molecule. Hydroxyl radicals are highly reactive and consequently short-lived; The first reaction with many volatile organic compounds (VOCs) is the removal of an hydrogen atom, forming water and an alkyl radical (R•). = •HO + RH → H2O + R• The alkyl radical will typically react rapidly with oxygen forming a peroxy radical = R• + O2 → RO2 RO2.
Its comprehension has been made possible since the discovery of water electrolysis by means of the titanium dioxide – TiO2. Commercial application of the process is called Advanced Oxidation Process(es) (AOP). There are several methods of achieving AOPs that can, but do not necessarily involve TiO2 or even the use of UV. Generally the defining factor is the production and use of the hydroxyl ion. (extracted from Wikipedia)
Photocatalytic Oxidation (PCO) is an emerging technology in the HVAC industry. In addition to the prospect of Indoor Air Quality (IAQ) benefits, it has the added potential for limiting the introduction of unconditioned air to the building space, thereby presenting an opportunity to achieve energy savings over previous prescriptive designs. As of May 2009 there was no more disputable concern raised by the Lawrence Berkeley National Laboratory data that PCO may significantly increase the amount of formaldehyde in real indoor environments. As with other advanced technologies, sound engineering principles and practices should be employed by the HVAC designer to ensure proper application of the technology. Photocatalytic oxidation systems are able to completely oxidize and degrade organic contaminants. For example, Volatile Organic Compounds found low concentrations within a few hundred ppmv or less are the most likely to be completely oxidized.(PCO) uses short-wave ultraviolet light (UVC), commonly used for sterilization, to energize the catalyst (usually titanium dioxide (TiO2)) and oxidize bacteria and viruses. PCO in-duct units can be mounted to an existing forced-air HVAC system. PCO is not a filtering technology, as it does not trap or remove particles. It is sometimes coupled with other filtering technologies for air purification. UV sterilization bulbs must be replaced about once a year; manufacturers may require periodic replacement as a condition of warranty. (extracted from Wikipedia)
In our equipment we use a patented process to affix TiO2 to a solid substrate, for this TiO2 to interact with UVC radiation at 253.7 nanometer (nm) which has the advantage that this wave length does not get adsorbed by the oxygen molecules, thus does not create any ozone – O3 (trioxygen). Naturally occurring ozone in the atmosphere is converted by the TiO2 / UVC interaction into normal dioxygen (O2) or other ambient gases which then get converted to benign matter, including diatomic oxygen (O2) which forms 20.9% of our ambient atmosphere.
Using recirculating return air as part of the incoming airstream is thus helping in this cleaning process, as the return air already passed before through this photo-catalytic oxidation process.
NOTE: Placing several PCOC units sequentially increases the dwelling time for the UV light interaction with the photocatalyst, thus multiplying the decomposition of VOCs and pathogens.