Can pavements clean the air around you?
A recent demonstration project carried out in the Netherlands showed that streets where pavements were treated with the pigment “titanium dioxide”, which is produced using chlorine chemistry, showed decreased smog levels compared to streets with normal pavements.
Air quality continues to be a problem in densely populated areas in Europe. High levels of air pollution such as smog resulting from transport or industrial emissions can cause adverse health effects to people living in affected areas. Researchers from the Eindhoven University of Technology recently developed and tested specially coated pavements slabs as a measure to help reduce smog levels on a street-to-street level. The pavement slabs were coated with titanium dioxide.
Compared to a street with normal pavements, the coated pavements reduced the average daily amount of smog of the street by 19%, and by up to 45% when conditions such as temperatures and humidity were at ideal levels.
One of the main manufacturing methods used for producing titanium dioxide is called the chloride process. Chlorine is used to extract titanium tetrachloride from titanium ores. The chlorine is recovered by reacting the titanium tetrachloride with oxygen to produce pure titanium dioxide. The chlorine can then be reused in the same process.
Oh yes: titanium dioxide is a very versatile pigment! You find it, among many other things, in tooth paste, paints and extra white paper.