Wednesday, 23 Sep 2020

Painting the Air Clean

Painting

Based on the report ” Revolutionary paint offers solution to air pollution” published in The Hindu, April 22, 2019 : https://www.thehindu.com/sci-tech/energy-and-environment/revolutionary-paint-offers-solution-to-air-pollution/article26903323.ece

What could chemistry and art have in common? As per the report published in “The Hindu”,22 April 2019, the two disciplines came together to paint a metro rail station along one of the busiest roads in Manila, Philippines.  KNOxOUT is a paint, developed by Pacific Paint (Boysen) Philippines, Inc. , to tackle air pollutants such as nitrogen oxide(NOx), mainly generated by vehicular emissions.

NOx is the combination of NO(Nitric oxide) and NO2 (Nitrogen dioxide). It is formed when nitrogen, released during fuel combustion, combines with oxygen. NOx can cause inflammation of the airways and  contributes to the formation of fine particles(PM) and ground level ozone, both of which have adverse side effects. (Source: http://www.icopal-noxite.co.uk/nox-problem/nox-pollution.aspx )

KNOxOUT reacts with nitrogen oxides (NOx) and neutralizes it through chemical reaction.

As explained in the Boysen website http://www.knoxoutpaints.com/about.do?id=20800 , this is how it works:

“BOYSEN® KNOxOUT™ contains CristalACTiV™ photocatalytic technology, which is ultrafine titanium dioxide, (TiO2) that absorbs energy from light and transforms ordinary water vapor into hydroxyl and peroxyl free-radicals at the surface of the TiO2.

These free-radicals, created in billionths of a second, become the reactive species that break down noxious air pollutants such as nitrogen oxides (NOx) that come into contact with the surface. Harmful NOx gas is converted to nitric acid that is rapidly neutralized by alkaline calcium carbonate particle in the paint, producing harmless quantities of calcium nitrate and negligible amounts of carbon dioxide and water. Calcium nitrate is water soluble and easily removed from the film, leaving a fresh surface ready to engage the next pollutant to come into contact with the film”…… “the ultrafine TiO2 is not consumed in the reaction, but is merely a catalyst that continuously generates free radicals as long as there is sufficient light, air and moisture. “

As per test results, a square metre of wall painted with KNOxOUT could remove 160 gms of NOx in one year. This is comparable to the air cleaning capacity of a mature tree. In urban areas where sufficient trees cannot be accommodated, this might just be the solution to address vehicular pollution. Project EDSA is an initiative that paints lung shaped trees and other art work along Philippines’ busiest thoroughfare. Similar projects have been taken up in other countries including a tunnel in The Hague, in the Netherlands, an indoor car park in Paris, France, a hive-like façade using KNOxOUT paint on a hospital in Mexico City.

Cost may be a hindrance to large scale deployment of this technology at present. However, with the level of the air pollution menace, is there an option?

To read the full report check out :

https://www.thehindu.com/sci-tech/energy-and-environment/revolutionary-paint-offers-solution-to-air-pollution/article26903323.ece

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