Abstract:
Climate change is one of the most pressing concerns of the planet Earth today. And the main cause of climate change in general is the air pollution and in particular the “greenhouse gases”. NOx is a family of various oxides of nitrogen that exist in the atmosphere. The most important oxide of Nitrogen however, from climate’s point of view is the nitrogen dioxide (NO2) as it reacts in the atmosphere to form tropospheric Ozone and acid rain. Through Ozone and nitrous oxide (N2O) formation NOx contribute towards global warming and thereby climate change. Photocatalytic compounds are known to have the properties of removing pollutants from air and water. In this research titanium dioxide was used as an additive to concrete samples for photocatalytic removal of NOx from the air. The work has already been carried out in the past, however, the innovation in this study was a comparison between the removal efficiencies of both Pure as well as Iron-Doped titanium dioxide nano-particles, when applied to concrete samples. Two types of concrete specimens namely mortar concrete samples and pervious concrete samples were constructed, and based on the findings of previous researches, by Hassan et al., and Maria Christina Burton, two best found methods of TiO2 application for NOx removal were chosen. After the application and curing periods the samples were orderly subjected to porosity tests, compressive strength tests, and finally the environmental tests. The results show that the addition of TiO2 to pervious concrete does reduces its porous nature to some extent, however even with the highest concentration of Titania (15%) all the pervious concrete samples were found to be within the target porosity range of 15% to 20%. Compressive strength tests of both the mortar and pervious concrete samples suggested that the strength of the concrete increased as the concentration of the TiO2 was increased from 0% to 15% replacement by weight of cement. Finally, the environmental tests were performed and it was found that the photocatalytic NOx removal efficiency of the concrete increases with the increasing concentration of TiO2. However, increasing concentration of TiO2 may not always be beneficial for concrete, as in the pervious concrete it reduce its porosity. Similarly in case of the mortar concrete the compressive strength starts decreasing when more than 18% of the cement is replaced with TiO2, (Husnain, 2015). Therefore an optimum concentration TiO2 was chosen to be 15% replacement by weight of cement as even at this concentration significant quantities of NOx removal were achieved during the environmental tests.
