1. 09/05/11 Kaushik K. Shandilya Emissions from Fuel Polycyclic Aromatic Hydro Carbons (PAH) Kaushik K. Shandilya (M.E. III Sem)
2.
3. 09/05/11 Kaushik K. Shandilya Mechanism of Formation of PAH During Combustion Majority of PAH in the environment are derived from reaction at high temperature during pyrolytic conditions during incomplete combustion Pyrolysis Complex organic molecules are partially cracked to smaller unstable radicals and creates O 2 deficient zone Pyrosynthesis These fractions are unstable and partly combusted and partly recombined to form stable PAH
4. 09/05/11 Kaushik K. Shandilya CO- 11.4 % H2 – 8.2 % CH4 - 2 % ORC – 0.5 % O 2 - 1.0 % Coal firing System Pyrolysis During combustion, reduced environmental conditions are formed around the flame and unstable organic radicals are formed CO- 18.2 % H2 – 1.1 % CH4 – 0.3 % ORC – 6.0 % O 2 - 0 % Automobiles Reduced Conditions Source: Diesel. Net
5. 09/05/11 Kaushik K. Shandilya Pyrosynthesis Source: H. Richter, J.B. Howard, Progress in Energy Combustion Science, Feb 2000 These fractions are unstable and partly combusted and partly recombined to form stable PAH
6. 09/05/11 Kaushik K. Shandilya Source-1: Emission Inventory Program USEPA Source-2: Bruce A. Benner, Environ. Sci. Technol. 1989, 23, 1269-1278 PAH Emissions by Category in USA Sources wise Emissions of PAH
7. 09/05/11 Kaushik K. Shandilya Vapour Pressure of PAHs Volatile Semi - Volatile Source: US Department of Health and Human Services
8. 09/05/11 Kaushik K. Shandilya % of Total PAH Associated with Particle Source: USPEA, Publications EPA-454/R-98-014
9.
10. 09/05/11 Kaushik K. Shandilya High Volume sampler for PAH Size selective inlet (Separation of PM>10microns) WINS Impactor (Separation of PM>2.5 and 10 microns) Teflon filter (PTFE) (Collection of PM<2.5 microns) PUF adsorbent (cartridge with ice jacket) (Collection of VOC) Dry gas meter Suction pump
13. 09/05/11 Kaushik K. Shandilya The PUF should be of the polyether type used for furniture upholstery, pillows, and mattresses. The PUF cylinders (plugs) should be slightly larger in diameter than the internal diameter of the cartridge Polyurethane Foam PUF Adsorbent
14. 09/05/11 Kaushik K. Shandilya “ PUF” vrs “XAD Resin” Technical Assistance Document for Sampling and Analysis of Toxic Organic Compounds in Ambient Air , U. S. Environmental Protection Agency, EPA-600/4-83-027, June 1983. PUF XAD Resin Collection efficiency of NV-PAH >99 >99 Collection efficiency of V-PAH 90-100 97-100 Loss of V-PAH at 25 O C in 30 days 10-15 <5 Flow characteristics in HVS Unchanged -ve impact Recovery More solvent Less solvent Species collected other than PAH Pesticides, PCB, Dioxins Poor collection PUF is widely used for PAH sampling
15. 09/05/11 Kaushik K. Shandilya Naphthalene, acenaphthylene, and acenaphthene possess relatively high vapor pressures Collection efficiency less than 35% Avoid PUF if… PUF Adsorbent XAD Resin is a suitable option
16.
17.
18.
19. 09/05/11 Kaushik K. Shandilya Types of Filters for “PM” sampling Cellulose fiber Cellulose fiber (often called – Paper filters) Cellulose Acetate Cellulose nitrate and mixer of esters (cellulose acetate) Pure Quartz fiber Mat of Quartz fiber Mixed Quartz Quartz + Borosilicate Glass fiber Borosilicate glass fiber Teflon coated glass fiber Borosilicate glass fiber with a mat of Teflon Teflon Carbon based material stretched between methyl pentane/propylene Nylon Pure nylon
20.
21. 09/05/11 Kaushik K. Shandilya Loss of PAH during measurement Baseline values in the filter and oil Establishing blank tests and extraction with methanol before sampling Sampling Cold bath for PUF filter, minimum exposure to sunlight, add surrogate standards Storage of samples and analysis Storage in ice bath and incandescent lighting in the lab
22.
23.
24.
25. 09/05/11 Kaushik K. Shandilya Higher degradation in case of 6 to 8 ring compounds More degradation with less ‘EC’ is present Function of particle surface area Photodecomposition of PAH Source: Ingwen Chinm J. Environmental Pollution, 114, 2001
26. 09/05/11 Kaushik K. Shandilya Reaction of PAH with Atmospheric pollutants General ambient concentrations of these pollutants are far less Pollutant Study Findings Ref SO 2 (Exposed to 10000 ug/m3 for 10 days) No change in the concentration for 16 PAH Butler, J.D, Atmos. Env. 15, 1981 Ozone (Exposed to 2 PPM for 10 days) Considerable degradation with half life ranging 0.1-0.6 h -1 Kataz, Envi. Sci. Technol. 9, 1977 NO 2 Exposed to 3000 ug/m3 for 24 hours) About 1% reduction and no change in lower ring compounds Pitts et. al. Science, 202, 1978
27. 09/05/11 Kaushik K. Shandilya Storage of samples and preservation Filter cassettes Filter holder and ice box
28. 09/05/11 Kaushik K. Shandilya Analysis of samples by High Performance Liquid Chromatography
29. 09/05/11 Kaushik K. Shandilya Environment… -Not our bequeathal property -But borrowed from children
![[object Object],[object Object],[object Object],[object Object],[object Object],09/05/11 Kaushik K. Shandilya What are PAH compounds?](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)