Evaluation Test of NO Degradation by Nano-TiO2 Coatings on Road Pavements under Natural Light

Reducing or degrading nitrogen oxides (NOx) emitted by automobile exhausts has diversified ways. This paper presents a solution to degrade NO by Nano-sized titanium dioxide (Nano-TiO2) mixed with coating materials for traffic marking on road pavements. The effect on degradation was evaluated by adopting a simple laboratory test with statistical analysis. During the test, five different contents of Nano-TiO2, 2%, 3%, 4%, 5%, and 6%, mix with a coating material for pavement marking, followed by an interpretation of the micro mechanism of degradation effect. The results show that the pavement marking coatings mixed with Nano-TiO2 has a good performance on NO degradation. The effect of degradation is increased with increasing the content of Nano-TiO2 particles, however. At the same time, a peak value with about 70% of the maximum removing rate existed when applying 4% Nano-TiO2 due to the agglomeration phenomenon for nanoparticles close to each other for adding more Nano-TiO2. The methods to reduce agglomeration are also suggested, and a routine field test for all potential traffic coating materials is recommended in this study.