| Dachang and Shanxi Road region were selected as inspected spots in Nanjing. Samples of inhalable particles(PM10) in ambient air were gathered month by month for one year, using big flux sampling equipment and PM10incision equipment. Scanning Electron Microscope and X-ray energy dispersive spectrometer were used to analyze the morphology and chemical composition of inhalable particles. At the same time, the PM10pollution change laws of different functional partition, different season of Nanjing city was studied.16PAHs were selected as the EPA designated materials with priority control. The PAHs level of pollution, concentration characteristics and seasonal change law was analyzed by using high performance liquid chromatography. The PAHs in the PM10of several typical pollution sources (coal combustion, coke plant, motor vehicle and dining hall) were analysed qualitatively and quantitatively. The composition and distribution of PAHs of different pollution sources were compared to each other, and, the source components spectrum were collected. Then, The CMB receptor model was used to analyse the sources of PAHs in the PM10. Baesd on the "electrostatic-granular layer filtration composite technology", a new type of "electrostatic-charged particle layer filtration compound dust removal technology" has been designed in this research for removing PM10. Theoretical analysis illustrated the dust removal mechanism and the main influence factors. Homemade charged particles were used to study the best removing process conditions of the PM10.(1) Study on the PM10physical characteristics and space-time dynamic change rule of Dachang area and Shanxi Road in NanjingAtmospheric particulates in two typical areas of Nanjing are very complex, Dachang area (a typical industrial zone) shows a more inerratic pattern, such as massive, the columnar, needle, layer, globular aggregation are commonly inspected, with carbonate, sulfate, aluminum silicate as ingredients primarily. But, Shanxi Road (a typical business district) shows a irregular pattern, such as smoke, biomass, common collection of irregular minerals, etc., PM10concentration in Nanjing is higher than the secondary standard in1996national environmental air quality standards. The order of the concentration of PM10of four different seasons is:spring> summer> autumn> winter, which is relative to the local climate. PM10concentration of Dachang is significantly higher than Shanxi Road from a region of view, and the PM10concentration in Shanxi Road is beyond the secondary standard sometimes. Overall, the PM10pollution is heavy, which exceeds the secondary standard in1996national environmental air quality standards.(2) The composition characteristics and source analysis of the metal elements in PM10in Nanjing15metal elements are determined by ICP-AES, Hydrogenation method and ions imprinted method. Analysis shows that enrichment factor of Cr、Ni、Cu、Zn、Pb、Cd、As of Dachang and Ni、Cu、Zn、Pb、Cd、As of Shanxi Road are greater than10, the results indicate that these elements mainly come from anthropogenie Pollution. PM10of Shanxi Road mainly come from vehicle exhausts, and Dachang was mainly sourced from industrial pollution.(3) The space-time dynamic change regulation research of PAHs in PM10in NanjingThe average PAHs concentration of Spring, Summer, Autumn, Winter in Dachang area is107.256ng·m-3、121.890ng·m-3、111.839ng·m-3and88.605ng·m-3, respectively, and in Shanxi Road is76.276ng·m-3、52.904ng·m-3、42.561ng·m-3and75.815ng·m-3, respectively. The average PAHs concentration of four seasons in Dachang was significantly higher than that of Shanxi Road, and the proportion is1.406,2.304,2.628,1.169times respectively. Seasonal condition had a slight influence on the total amount of PAHs in Dachang area, while the seasonal variation are found in the concentration of PAHs in Shanxi road. The highest concentration was observed in spring with the lowest level in Autumn, and the value in winter was higher than that in summer. The contents of Anthracene, Fluoranthene, Benzo [b] fluoranthene, and Benzo [g,h,i] perylene in the two locations are petty high, exhibiting that coal combustion and traffic were the predominant sources for the pollution of Nanjin city, and the pollution from coal combustion was more severe in Dachang area.(4) Source assignment of PM10in Dachang area and Shanxi Road regionChemical Mass Balance (CMB) receptor models is established to simulate the pollution of Dachang area and Shanxi Road region, so as to determine the contribution of the pollution sources. The PAHs contribution rates of coal combustion, motor vehicle, coke-source and dining hall were obtained, with12.48%,25.61%,52.16%and9.75%in Dachang and9.65%,25.55%,52.83%and11.97%in Shanxi Road, respectively. This suggests that the main sources of PAHs are coke-source and traffic source in both areas.(5). Control of PM10with electrostatic-charged particle layer filtration compound dust removal technologyAccording to the "Electrostatic-charged particle layer filtration compound dust removal technology", passing through the electrostatic precipitator, the PM10is charged. Then the charged PM10was removed by the charged particle layer filter. Chitosan/attapulgite is an ideal charged particle material. The optimal condition for chitosan/attapulgite composition is that mix chitosan sol and attapulgite at1.5:1mass ration, and react3.5h at50℃. In the optimal conditions, the load rate(%) of chitosan in attapulgite is40.26%, with good modification stability. XRD, FT-IR and thermal analysis confirmed that the chitosan is successful loaded on the attapulgite surface. Chitosan/attapulgite Zeta potential is+46.28mV, and carrys positive electricity. The best removing process condition of charged particle filter of PM10is filtering time is70min, filter wind speed is0.42m·s-1, filter layer thickness is30mm, filtering particle diameter is0.756mm, particle uniformity is1.32, concentration of PM10is600μg·m-3. This process is very steady and good for industrialization amplification. |
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