LowEmissionAsphalt-136pg-WhitePaper-May2023

P a g e | 107 Photocatalytic Oxidation (PCO) of NOx Source: Texas A&M Transportation Institute (TTI) The moist air that has lost electrons is transformed into a hydroxyl radical (-OH). The HO 2 - and -OH (collectively oxyradicals ) form and assemble on and around the treated surface like TiO 2 generated Pac-Men that aggressively attack the carbon- hydrogen bonds present in ALL organic materials , producing complete oxidative decomposition of nearfield pollutants. For NOx and CO 2 , the presence of the oxyradicals converts toxic (to humans) nitrite gas (NO 2 ) into a harmless nitrate salt 226 and similarly CO 2 into a harmless carbonate, 227 both are simple “plant foods” , hence removing the airborne environmental threats. NO 2 + UV + H 2 0 (humidity) – H 2 NO 3 CO 2 + UV + H 2 0 (humidity) – H 2 CO 3 H 2 NO 3 – H + + HNO 3 H 2C O 3 – H + + HCO 3 HNO 3 – H + + NO 3 HCO 3 – H + + CO 3 226 soluble nitrate : also - sodium nitrate (NO 3 ) is the pure form of nitric acid which is an essential plant nutrient easily assimilated by all common types of vegetation. Post absorption, nitrate is transferred to leaves and roots where it is converted into chloroplast (chlorophyll) for photosynthesis and later amino acids and fully metabolized. 227 carbonate : also – carbon trioxide (CO 3 ) is a salt of carbonic acid and is an essential plant nutrient easily assimilated by all common types of vegetation. Carbonate is absorbed by vegetation via photosynthesizing or biological carbon fixation by all photoautotrophic plants; is converted into carbohydrates ; and stored and utilized for energy. Perennials can store carbonate derivatives for decades and even centuries.