| With the rapid development of economy,the number of motor vehicles is increasing,and the air pollution caused by automobile exhaust is becoming more and more serious,which has become an urgent problem to be solved.Based on the field of road engineering materials,it is of great environmental significance and social value to study and prepare asphalt pavement materials that can degrade automobile exhaust and adsorb pollutants.The semiconductor photocatalytic material represented by Ti O2 can be used to degrade automobile exhaust and catalyze the decomposition of road sewage,while nitrate ion（NO3-）,a secondary pollutant after the photocatalytic decomposition of nitrogen oxides（NOx）in automobile exhaust,will increase the precipitation of nitrogen salts in the soil around the road and cause eutrophication of the water body with rainwater runoff.Layered bimetallic hydroxides represented by Mg-Al hydrotalcites（Mg Al-LDHs）and their burned products（Mg Al-LDO）have a specific surface area.The main research contents and results of this paper are as follows:（1）Firstly,the test system for photocatalytic degradation of tail gas is developed,the main components and functions of the test system are determined,the basic parameters of each test and the evaluation index of degradation are determined,and the detailed operation method of the test system is formulated,so as to analyze and study the degradation performance of photocatalytic pavement materials.（2）Select different graded asphalt mixture types,design the mixture ratio of photocatalytic pavement materials,and explore the influence of photocatalytic pavement materials on road performance under different Ti O2 content.As a result,on the surface,since Ti O2 belongs to nano-scale materials and its chemical properties are stable,adding it by internal mixing method will not have adverse effects on Marshall mechanical index,high temperature stability,water stability,water permeability and skid resistance of asphalt mixture.（3）The experimental results of photocatalytic degradation of NO show that the recommended content of photocatalyst Ti O2 powder in the photocatalytic asphalt mixture prepared by internal doping method is 30%～40%.Under the lower limit of30%,the degradation efficiency of NO in AC group and OGFC group is 31.73%and33.39%respectively.The photocatalytic asphalt mixture prepared by surface coating method,the recommended dosage of photocatalyst Ti O2 solution is 60g/900cm2,and the coating concentration is 30g/L.At this time,the degradation efficiency of NO in AC group and OGFC group is 50.93%and 50.09%respectively.Gradation type has no obvious influence on degradation efficiency;The degradation efficiency of NO increases with the increase of temperature at 20℃～25℃,and is almost unaffected by temperature at 25℃～30℃.Considering only the degradation efficiency and average reaction rate,the coating type is better than the internal mixing type,but the actual addition scheme still needs to consider factors such as economy and construction convenience.（4）Design a test device to explore the degradation efficiency of photocatalytic asphalt mixture for liquid phase pollutant methylene blue solution and the adsorption efficiency for NO3-.The experimental results show that the degradation efficiency of methylene blue solution reaches 20.14%under the condition of doping 30%Ti O2,and the porosity has little effect on the degradation efficiency.When Mg Al-LDO is added to asphalt mixture with 30%internal doping,the maximum adsorption efficiency of NO3-is 31.42%,and the unit adsorption capacity is 0.85 mg/g.The adsorption efficiency increases with the increase of temperature from 20℃to 30℃,and decreases with the increase of initial concentration of NO3-solution.Figure:[68]table:[39]reference:[61]... |
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