Study on Photo catalytic Self-Cleaning concrete using Titanium Dioxide
CHEMICAL REACTION
The photo catalytic efficiency of a system can be assessed by a number of criteria again
being influenced by various circumstances and factors. The degradation of nitric oxide (NO) or
more general of nitrogen oxide (NOx), also referred to as DeNOx- process (denitrogenization),
delivers a suitable model to assess the ability of surfaces for air purification. This
denitrogenization process can roughly be described as a two-stage reaction on the surface of a
photocatalyst, which in most of the cases is titanium dioxide in the anatase modification or
variants of it. For this purpose a certain amount of water molecules, supplied by the relative
humidity and electromagnetic radiation are required to start a degradation process. The electro-
magnetic radiation (E) is expressed by the product of Planck’s constant (h) and the frequency (ν).
Herewith, the two steps can be summarized as follows:
The free hydroxyl radicals (OH) originate from the photo generated water electrolysis on the
anatase surface. These two reactions describe the processes on the surface of the sample and
therefore define the compounds which have to be measured in order to evaluate degradation
ability. With the help of the deployed chemiluminescence NOx analyzer the amounts of NOx and
NO can be quantified. Subsequently, the amount of NO2 can be calculated by difference
formation. Hence, a quantitative analysis can be conducted.
Fig
6.1:
Che
mic
al
reac
1
Dept. of Civil Engineering, SIMAT Vavanoor
CHEMICAL REACTION
The photo catalytic efficiency of a system can be assessed by a number of criteria again
being influenced by various circumstances and factors. The degradation of nitric oxide (NO) or
more general of nitrogen oxide (NOx), also referred to as DeNOx- process (denitrogenization),
delivers a suitable model to assess the ability of surfaces for air purification. This
denitrogenization process can roughly be described as a two-stage reaction on the surface of a
photocatalyst, which in most of the cases is titanium dioxide in the anatase modification or
variants of it. For this purpose a certain amount of water molecules, supplied by the relative
humidity and electromagnetic radiation are required to start a degradation process. The electro-
magnetic radiation (E) is expressed by the product of Planck’s constant (h) and the frequency (ν).
Herewith, the two steps can be summarized as follows:
The free hydroxyl radicals (OH) originate from the photo generated water electrolysis on the
anatase surface. These two reactions describe the processes on the surface of the sample and
therefore define the compounds which have to be measured in order to evaluate degradation
ability. With the help of the deployed chemiluminescence NOx analyzer the amounts of NOx and
NO can be quantified. Subsequently, the amount of NO2 can be calculated by difference
formation. Hence, a quantitative analysis can be conducted.
Fig
6.1:
Che
mic
al
reac
1
Dept. of Civil Engineering, SIMAT Vavanoor
