The Chemistry of UV-PCO
Photocatalytic Oxidation (PCO) occurs when UV-A light (from sunlight, fluorescent light or UV-A LEDs) energizes titanium dioxide(TiO2) and triggers two chemical reactions that lead to the near instantaneous formation of hydroxyl radicals and super oxide anions. These highly reactive chemical agents then instantly interact at the treated surface to accelerate the environmentally beneficial decomposition of all organic pollutants (mold, oil, rubber, bio-film, methane and VOCs) through oxidation and to reduce/neutralize inorganic pollutants (such as NOx and SOx).
Hydroxyl radicals (OH*), nature’s strongest non-poisonous oxidizing agent, are formed when the light energized TiO2 pulls a hydrogen atom away from the H2O water vapor in the air (humidity). The hydroxyl radicals formed on the treated surfaceact like pac-men and aggressively attack the carbon hydrogen bonds that are present in all organic molecules over and over until nothing is left from this oxidation process except water and a small amount of CO2. Life Cycle Analyses of PCO have found the technology to be a major net environmental good. The small amount of CO2 produced is more than offset by the gains from reducing methane, NOx and VOCs (all major criteria pollutants) in the atmosphere and the gains from reduced water, chemical and energy usage through reduced maintenance.
Super oxide anions (O2-), one of nature’s strongest reducing agents, are formed when oxygen molecules in the air (O2) interact with light energized TiO2 and receive an extra electron creating O2-. When polluted air comes into contact with a PURETI treated surface, these super oxide anions interact with the NOx (the highest heat retaining major greenhouse gas and the key ingredient in acid rain and smog) and remove it from the atmosphere reducing it to benign nitrates. The light activated, smog-reducing power of PCO technology is extensively documented and definitively proven in the scientific literature.
This process all happens in billionths of a second and continues to scrub the air as long as light, humidity, PURETi and air flow are present. The self-cleaning function of photocatalytic surfaces are further assisted by the fact that photocatalytically active surfaces are hydrophilic or water sheeting. This water sheeting effect allows small amounts of water to easily rinse away any inorganic particulates that may be held to the surface by gravity or electrostatic forces.