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School of Environmental Engineering UNIVERSITY MALAYSIA PERLIS

FUNDAMENTAL TO ENVIRONMENTAL ENGINEERING EAT232/3 SEM I, 2014-2015 AIR POLLUTION-Introduction/Particulate Matter S. Ragunathan AMPRIM, MIMM, AMESM Dip. (Public Health), B. Tech (Env), MSc. (Env. Eng), phD(Polymer Recycling).

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School of Environmental Engineering UNIVERSITY MALAYSIA PERLIS

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  1. FUNDAMENTAL TO ENVIRONMENTAL ENGINEERING EAT232/3 SEM I, 2014-2015 AIR POLLUTION-Introduction/Particulate Matter S. Ragunathan AMPRIM, MIMM, AMESM Dip. (Public Health), B. Tech (Env), MSc. (Env. Eng), phD(Polymer Recycling) School of Environmental EngineeringUNIVERSITY MALAYSIA PERLIS

  2. WHAT IS REQUIRE OF YOU ? At the end of these 1 hours • What is air pollution? • What are the major natural and anthropogenic sources. • Basic calculation on Particulate & Gasous Pollutant. • Suggest control strategy for air pollutant ?

  3. Air Pollution (Terms) • The presence in the outdoor atmosphere (ambient air) of one or more contaminants in such quantities and for such duration as to be harmful or injurious to : - Human health or welfare - Animal or plant life - Property • Addition of harmful substances to the atmosphere resulting in damage to the environment, human health, and quality of life. 

  4. Sources of Air Pollution NATURAL SOURCES

  5. Sources of Air Pollution Anthropogenic Sources

  6. Sources of Air Pollution Indoor air pollution

  7. Air Pollutant-Major Contributes 1. Components of fossil fuel • a. Hydrocarbons • i. when incompletely burned form: carbon monoxide, unburned hydrocarbons, CO2 and water • ii. when completely burned form: CO2 and water • b. Contaminants: • i. sulfur → (heated) → Sulfur monoxide, dioxide, trioxide, etc. (SOx) • ii. Mineral contaminant → (heated) → Particulates (e.g. lead and mercury) • iii. Nitrogen gas → (heated) → Nitric oxide and nitrogen dioxide (NOx) • c. Many of the pollutants react with solar energy and water to produce secondary pollutants, for example: SOx + H2O → H2SO4 (sulfuric acid) 2. Photochemical smog a. Unburned hydrocarbons and NOx from power plants and automobiles react with sunlight to form secondary pollutants: ozone, formaldehyde, etc. Ozone erodes rubber, irritates the respiratory system and damages plants.

  8. Air Pollutant-Control Strategies Technologies • Bag filter – remove particulates • Cyclone collector – particulate removal • Electrostatic precipitator – removal of particulates • Spray collector (also called a scrubber) removes particulates and gases such as sulfur dioxide goes through mist of liquid chemicals (water and …) • Catalytic converter (on cars) – transform toxic pollutants into less harmful forms

  9. Air Pollutant-Control Strategies Redox reactions: • Oxidation: converts combined CO and unburned hydrocarbons into CO2 and H2O • Reduction: Converts NOx to N2, CO2, and H2O Laws Enforcement: a. Widely adopted into automobiles/Emission in response to Environmental Quality Act (Clean Air Regulation) b. Began phasing out of tetraethyl lead (anti-knocking agent) in gasoline in

  10. Air Pollutant-Characterization Particulate Matters PAN- Peroxyl acetylenitrate

  11. Air Pollutant-Characterization NAAQS (National American Air Quality Standard)

  12. Air Pollution (Terms) Terminology / Definition • Aerosols: :Solid or liquid particles smaller than E10-6m (100 microns). • Condensation Aerosol: :Aerosol formed by condensations of vapor or reactions of gases. • Dispersion Aerosol :Formed by grinding solids, dispersion of dust, atomization of liquids. • Fog: :High level of water droplets. • Haze: :Decreased visibility due to presence of particles. • Mist: :Liquid particles. • Smoke: :Particles resulting from incomplete combustion function. Particulate(Liquid or Solids) Gaseous (Gas phase)

  13. Air Pollution (Terms) Definitions Terminology

  14. Air Pollutant-type Particulate Matter

  15. Air Pollutant (Particulates) • What Stoke’s Law tells us is that, all other things being constant, dense particles settle faster, larger particles settle faster, and denser, more viscous air causes particles to settle slower. • Stoke’s Law is used in several ways. We can predict settling rate for a given particle if its diameter and density are known. Another way in which Stoke’s Law is used is to estimate particle diameters (called "Stoke’s diameter") from observed settling rates.

  16. Air Pollutant (Particulates)-Dp d2 = diameter of particle squared in g = acceleration due to gravity in r1 = particle density in r2 = air density in η = air viscosity in poise where: v = settling velocity in • Stoke’s Law is the relationship that relates the "settling rate" to a particle's density and diameter. Stoke’s law is given as: • where: v = settling velocity in g = acceleration due to gravity d2 = diameter of particle squared r 1 = particle density in r 2= air density η = air viscosity in poise

  17. Question on (Dp) What is Stoke’s diameter (aerodynamic Diameter) of a particle that falls at 1 m/s in air at 0o C and 1 atm. Let's check the units before we put in numbers to do the calculation. 1m/s = 100cm/s

  18. Air Pollutant (Particulates)-Dp Solution: What is Stoke’s diameter (aerodynamic Diameter) of a particle that falls at 1 m/s in air at 0o C and 1 atm. dp = 0.0177 cm which equals 177 μ m. This is a very large particle (perhaps it could be wind blown dust), but the settling velocity we used for this example was quite high.

  19. Air Pollutant (Particulates)-Dp -When air is sampled for particulate matter, particles are collected according to the effective or Stoke’s diameter. -Particulate matter is classified as "Total Suspended Particulate", TSP, PM10 and PM2.5. -TSP is the total mass of particulate matter suspended in air, and the units of this measurement are µ g/m3. -PM-10 refers to the total mass of particulates in an air sample that are smaller than 10 µ m in diameter, and likewise, -PM 2.5 is the mass of particulates in an air sample that are less than 2.5 µ m in diameter.

  20. Air Pollutant (Particulates)-Dp TSP : Total suspended particulate matter RSP : Respirable suspended particulate matter PM10 : Particulate matter of less than 10 um; equivalent to RSP. PM2.5 : Particulate matter of less than 2.5 um

  21. Nomenclature vs. Diameter

  22. Air Pollutant (Particulates)-Human Health The larger a particle is, the more likely it is to deposit into the upper part of the respiratory sys. The smaller a particle is, the deeper it can get into the respiratory system.

  23. Air Pollutant (Particulates)-Human Health • Epidemiological evidence associates atmospheric particles with diseases and mortality. • Particles penetrate the lungs, blocking of air way(Asthma) and irritating air passages. • Particles themselves could exert toxic effects. (toxic substances present in the particles) [Polycyclic Aromatic Hydrocarbons are examples of toxic substances in aerosols.] • Asbestosis, Malignant Mesetholimea (Cancer)

  24. GASOUS AIR POLLUTANT Definition: SOx, NOx, CO, O3 H2S, CH4, CFC and etc

  25. GASOUS AIR POLLUTANT(UNITS/MEASUREMENT) • Many of the units that are routinely used in atmospheric chemistry do not conform to MKS units. Some are cgs. Some are based on number of molecules. Some are based on mass. • Often, units originate from the original and most popular measurement techniques. (e.g., mass for aerosols). then • Units fall into three classes: • massor volume mixing ratio () • Concentration NA, or moles per unit volume (called concentration, or density) • 3. mass or number of molecules per unit area integrated vertically between the observation point and space (called column density).

  26. AIR POLLUTANT Units (Mixing Ratio) • Mass or volume mixing ratio • You must specify by mass (with an “m” at the end) or by volume (with a “v” at the end). •  is often used as the mixing ratio, but not always. • Common units are : ppm= 10-6, ppb = 10-9; ppt = 10-12; ppq = 10-15 • The equivalent “correct” MKS units to volume mixing ratios ( )is : • mol/mol = ppmv; • nmol/mol = ppbv; • Pmol/mol-1= pptv; • Mixing ratios of gases and aerosols are transported.

  27. Units (Conc./ nM, nA) • mass, molecule number, or moles per unit volume (called concentration, or density) • You must specify mass per unit volume or number of molecules per unit volume. • nA or [A] is often used to specify concentration. (Concentration Number) • For gases, molecules cm-3 is the most common unit. nM (Molecule Number) • To go to other p and T, nM = 2.69x1019 (p/1013) (273/T) or nM = 7.25x1018 (p/T) molecules cm-3. Note: [No/standard volume] =6.02x1023/22,400 = 2.69x1019 molecules/cm-3 at STP.

  28. Units (Column Density) • mass or number of molecules per unit area integrated vertically between the observation point and space (called column density) • important for remote sensing of atmospheric gases. • to get this, must integrate the concentration of the gas from the surface to space: N = z nA dz • usual units are molecules cm-2 • column ozone is measured in Dobson Units (DU). 300 DU is equivalent to a 3 mm thick layer of pure ozone at STP (1013 hPa, 273 K). • N = z NAdz

  29. Unit Conversion gaseous pollutant (mol/mol = ppmv) Conversions between: 1.Mixing ratios( A), mg/m3 or 2. Number conc. (NA) 3. Mass conc. (MA) 1. For mixing ratio Ato number concentration nA, nA = (A )nM nA = { (ppmv x 10-6 )*nM }molecules/ cm3 whereby nM = 2.69x1019 (p/1013) (273/T) molecules/ cm3. nM = 7.25x1018 (p/T) molecules/ cm3. 2. For ppmv(A)to mass concentration (MA) in g m-3 (MA)= {ppmv x (1000/22.4)(p/1013)(273/T)(Mwt)} g m-3 . (MA)= {ppmv x 12.03 {p (in hPa)/T (K)} Mwt }μg m-3 . 3.For mass conc. MA(mg/m3) to (PPMV) ppmv=[(mg/m3)(273.15 + ºC)]/ [12.187 Mwt]

  30. Problem 1 Problem 1.1 On the hot day in Perlis, plumes from power plants in Kuala Perlis can contain as much as 10 ppbv of sulphur dioxide (SO2). a) What is the number concentration of SO2? b) What is the mass concentration of SO2? c) If all of this SO2 is converted over to sulphuric acid, H2SO4, what is the resulting mass per unit volume of the sulphuric acid?

  31. Air Pollution -Solution 1 • Solution 1.1 • In UniMAP Perlis, a typical daytime temperature is 303 K and pressure is 970 hPa. Thus, the air number density is: • nM = 2.69x1019(970/1013)(273/303) = 2.3x1019molecules cm-3 • To get from ppbv to SO2 concentration, we must do the following: • nSO2 =(10 x 10-9) x nm = 10-8 x 2.3x1019 = 2.3x1011molecules cm-3 • To get the mass, we must multiply by the molecular mass. • SO2 molecular mass = (0.032 + 2 x 0.016)/6.02x1023 = 1.06x10-25kg • molecule • So the total mass concentration is: • MSO2 = (2.3x1011 molecule cm-3 )x(1.06x10-25 kg molecule-1) • = 2.4x10-14kg cm-3 • = 24 g m-3

  32. Air Pollution (Solution 1….cont) • Solution 1.1 • If it is all converted over to H2­SO4, then the total mass associated with each S02 atom is not 0.064 kg/mole, • As for H2­SO4, but is (2x0.001+ 0.032 + 4x0.016 ) = 0.098 kg/mole. • Thus, the total sulfuric acid mass is • Mass of H2SO4 = (0.098/6.02x1023) x 2.3x1011 • = 3.7x10-14 kg cm-3 • = 37 g m-3

  33. Exercise 2 Question 2 Plumes from Industrial estate in Kuala Perlis may contain as much as 20 ppbv of Nitrous dioxide (NO2). Assume Temperature as 30°C and pressure 970 in Hg. a) What is the number concentration of NO2? b) What is the mass concentration of NO2? c) If all of this NO2 is converted over to sulphuric acid, HNO3, what is the resulting mass per unit volume of the Nitric acid?

  34. Task for next Lecture/Wishes Read more about SOx , NOX and CO (Thank You for being my excellent students) * Understanding is the key to knowledge and wisdom.

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