The Chemistry of UV-PCO
Photocatalytic oxidation (PCO) occurs when UV-A light (sunlight, fluorescent light or UV-A LED) activates the 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 (OH*) radicals, nature's strongest non-poisonous oxidizing agent, are formed when the TiO2 energized with light extracts a hydrogen atom from H2O water vapor in the air (moisture). The hydroxyl radicals formed on the treated surface act as pac-men and aggressively attack the carbon hydrogen bonds that are present in all organic molecules again and again until there is nothing left of this oxidation process except water and a small amount of CO2. PCO life cycle analyses have found the technology to be an important net environmental asset. The small amount of CO2 produced is more than offset by gains from the reduction of methane, NOx and VOC (all major pollutant criteria) in the atmosphere and gains from reduced use of water, chemicals and energy through reduced maintenance.
Superoxide (O2-) anions, one of nature's strongest reducing agents, are formed when oxygen molecules in the air (O2) interact with oxygen. TiO2 with light energy and receive an extra electron that creates O2-. When polluted air comes into contact with a surface treated with O2-. PURETI, these superoxide anions interact with NOx (the largest greenhouse gas that retains heat and is the key ingredient of acid rain and smog) and remove it from the atmosphere by reducing it to benign nitrates. The power of PCO technology, activated by light and reducing smog, is widely documented and definitively proven in scientific literature.
This process occurs in billionths of a second and continues to clean the air whenever there is light, moisture, PURETi and airflow. The self-cleaning function of photocatalytic surfaces is reinforced by the fact that photocatalytically active surfaces are hydrophilic or water. This water-coating effect allows small amounts of water to remove any inorganic particles that can be kept in contact with the surface by gravity or electrostatic forces.