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TiO2 paint: At war with pollution

| Friday November 9th, 2007 | 4 Comments

tio2.jpg
Commercial and urban buildings have a large variety of different exterior applications available, also known as it’s “skin.” Some buildings are painted in order to preserve and protect the surface exposed to the elements. The problem with painting applications is that it degrades over time and releases harmful toxins into the environment.
With the endless array of environmental products and innovations that are prevalent in today’s world, it’s no wonder there is a new paint on the cusp of bucking the damaging trend of its predecessor. Imagine a paint that can make a positive contribution to the environment and urban ecology in particular. How? By cleaning up the pollutants that are transported in the air, more specifically, by reducing the levels of nitrogen oxides in the surrounding atmosphere.
Millenium Inorganic Chemicals, a British R&D firm has developed what they intended to appropriately name “Ecopaint.” This paint utilizes the same photo catalytic process of the anti-smog cement developed and under going testing in Italy. However, it has the advantage of being applicable to many different surface applications.


The paint is formulated on a base of polysiloxane, a polymer consisting of silicon. The active ingredients are tiny spherical nanoparticles made up of calcium carbonate and titanium dioxide (TiO2). This polysiloxane base is porous enough to allow nitrous oxides to diffuse through it and effectively stick to the nanoparticles. In turn, sunlight provides the energy to convert the nitrous oxides into nitric acid which is either disposed of by rain or neutralized by the alkaline properties of calcium carbonate and converted into carbon dioxide, calcium nitrate, and water. These profound chemical transformations are triggered by the ultraviolet radiation absorbed by the nanoparticles. Another advantage of these nanoparticles worth mentioning is that the particles are so small that the paint is initially clear and colorless making it receptive to coloring pigments.
This is not the only sweet feature to this revolutionary paint, over time; the more smog that is neutralized by the paint the more the paint is chemically transformed. The manufacturer claims that for the average 0.3 millimeter layer of paint in a heavily polluted urban environment, the amount of calcium carbonate levels are sufficient to last at least five years. Once the lifecycle of the calcium carbonate is reached, the titanium dioxide will continue to break down nitrous oxides and the byproduct, nitric acid, will begin to discolor the paint providing a strong visual indicator that the paint is ready to be replaced.
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  • Alex

    but nanoscale TiO2 maybe pollute the air, water or solid again. How and what to deal with?

  • Heather

    It looks like the nitric acid is being discharged into local water with assumption that it’s not doing any harm. If the calcium carbonate is gone that’s what will happen. From what I understand, nitric acid is explosive when it come into contact with arsenic. Arsenic is naturally occuring is some groundwater, but it’s also produced from the Nitrofication Denitrification process sewage treatment plants are installing in response to water quality regs, so it’s in ambient water. What happens if the maintenance is ingored, calcium isn’t there and nitric acid and arsenic come into contact in ambient water? How much do we need for there to be an explosive reaction? What about the explosive ammonium nitrate salt formation? It doesn’t just go away.

  • Heather

    It looks like the nitric acid is being discharged into local water with assumption that it's not doing any harm. If the calcium carbonate is gone that's what will happen. From what I understand, nitric acid is explosive when it come into contact with arsenic. Arsenic is naturally occuring is some groundwater, but it's also produced from the Nitrofication Denitrification process sewage treatment plants are installing in response to water quality regs, so it's in ambient water. What happens if the maintenance is ingored, calcium isn't there and nitric acid and arsenic come into contact in ambient water? How much do we need for there to be an explosive reaction? What about the explosive ammonium nitrate salt formation? It doesn't just go away.

  • Heather

    It looks like the nitric acid is being discharged into local water with assumption that it's not doing any harm. If the calcium carbonate is gone that's what will happen. From what I understand, nitric acid is explosive when it come into contact with arsenic. Arsenic is naturally occuring is some groundwater, but it's also produced from the Nitrofication Denitrification process sewage treatment plants are installing in response to water quality regs, so it's in ambient water. What happens if the maintenance is ingored, calcium isn't there and nitric acid and arsenic come into contact in ambient water? How much do we need for there to be an explosive reaction? What about the explosive ammonium nitrate salt formation? It doesn't just go away.