| The rapid development of city traffic has brought great convenience for people,but automobile exhaust results in severe pollution to city air environment. Automobileexhaust degradation has been one of the urgent problems now.This study mainly focuses on the field of urban road infrastructure constructionand maintenance.A new photocatalyst coating which is designed as road material isproduced by evenly mixing photocatalytic material TiO2into silicone acrylateemulsion at a certain mass ratio. This new coating can degrade automobile exhaust ingas concentration relatively large area and will not affect the normal function ofmunicipal infrastructure.Then it can be feasibly used into the urban road infrastructureto degrade harmful gases and protect air environment.At present, PM2.5is known as the best index to evaluate air quality all aroundthe world and automobile exhaust is one of the main components of PM2.5. In thisstudy, the environmental efficiency of nanometer titanium dioxide coating used inurban road infrastructure is tested in laboratory according to the degradation ofautomobile exhaust and the decrease of PM2.5. First, a new road material based onnanometer titanium dioxide is studied. In order to avoid nanometer titanium dioxidedispersing and making a second pollution to the atmosphere, nanometer titaniumdioxide is mixed into silicon emulsion. It is very convenient to paste nano titaniumdioxide coating material on the surface of the road infrastructure. In order to test itsengineering practicability, this photocatalyst coating is plastered on asphalt concretespecimen and fundamental pavement performance tests are carried out indoors.Second, a new test device used to degrade automobile exhaust and decrease PM2.5isdeveloped. This device can simulate the actual road environment under differentconditions as much as possible. Third, considering that many factors will affect thecatalytic performance of nanometer titanium dioxide coating, light condition, mixproportion and the reusable degradation efficiency are adopted as main influence factors in experiment. Finally, the decrease of PM2.5value by using nano titaniumdioxide coating in urban road infrastructure is tested at some specific factors, such asdifferent dosage of photocatalyst coating, reusable capability and different height toroad surface etc.The test results show that: light is the key factor to determine nano titaniumdioxide catalytic efficiency. When test specimen separately exposing at Ultravioletlight (UV) lamp and sunlight, the degradation rate of HC are23.6%,30.6%, thedegradation rate of NOXare57.9%,60%; when the mix proportion between nanoTiO2and silicone acrylate emulsion are separately1:5,2:5,1:2,3:5, the degradation rate ofHC are25%、29.1%、32.4%、34.1%and NOXdegradation rate was33.4%、36.2%、39.4%、42.1%. The optimum ratio is0.5-0.6. In reusable degradation test, thedegradation rate of HC are31%、30.7%、30.4%、30.6%, NOXdegradation rate are36.4%、36%、36.2%、36.2%respectively.Experiment on decreasing PM2.5value is carried on at the optimal mixproportion. When specimen are separately exposed at UV lamp and sunlight, PM2.5decrease rate(DR) are43.7%,45.6%; when the plastering area of specimen areseparately0m2,0.5m2and1.0m2, PM2.5DR are0%、24.4%、30.4%; when the heightaway the pavement surface are0.5m,1.0m and1.5m, PM2.5DR are40%、33.3%and23.3%; in reusable capability test, PM2.5DR are33.6%、1.2%and30.4%corresponding the number of repetition times. |
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