EnE 301: ENVIRONMENTAL ENGINEERING 3.0 Air Pollution and Control 3.1 Physical and Chemical Fundamentals 3.2 Major Air Pollutants and their Effects 3.3 Origin and Fate of Air Pollutants 3.4 Micro and Macro Air Pollution and Meteorology 3.5 Atmospheric Dispersion and Air Quality Model 3.6 Air Pollution Control of Stationary and Mobile Sources 3.7 Clean Air Act of RA8749 and Its Implementing Rules and Regulations

- Although polluted gas may not be “ideal”, it is still assumed that at the same temperature and pressure, different kinds of gases have densities proportional to their molecular masses. Physical and Chemical Fundamentals Ideal Gas Law where, = density of gas, kg/m 3 P = absolute pressure, kPa M= molecular mass, grams/mole T= absolute temperature, K R = universal gas constant = J/K · mole

- Since density is mass per unit volume, the expression may be rewritten in the general form as: Dalton’s Law of Partial Pressures where, V is the volume occupied by n moles of gas. - At K and kPa, one mole of an ideal gas occupies L. - Dalton's Law explains that the total pressure by a mixture of gases is equal to the sum of the pressures that each type of gas would exert if it alone occupied the container. where, P t = total pressure of mixture P 1, P 2, P 3 = partial pressure

- Dalton’s law may also be written in terms of the ideal gas law: Example No. 1: What is the density of oxygen, O 2 (in kg/m 3 ) at a temperature of K and at pressure of 98.0 kPa? Example No. 2: A gas mixture at 0 o C contains 250 mg/L of H 2 S gas. What is the partial pressure exerted by this gas in kPa per liter of gas? Seatwork No. 5: Calculate the volume occupied by 5.2 kg of carbon dioxide at kPa and 315 K.

Micrograms per cubic meter and parts per million are measures of concentration. Both are used to indicate concentration of a gaseous pollutant. Micrometer is used to indicate particle size. There is an advantage to the unit ppm which makes it the unit of choice. The advantage is that ppm is a volume-to- volume ratio. Changes in temperature and pressure do not change the ratio of the volume of pollutant gas to the volume of air that contains it. Units of Measure 1. Micrograms per cubic meter (g/m 3 ) 2. Parts per million (ppm) 3. Micron () or micrometer (m) 3 Basic Units of Measure:

where, GMW is the gram molecular weight of the pollutant. GMW is the gram molecular weight of the pollutant. Conversion of g/m 3 to ppm: The conversion of g/m 3 and ppm is based on the fact that at standard conditions (0 o C and kPa), one mole of an ideal gas occupies L. The conversion of g/m 3 and ppm is based on the fact that at standard conditions (0 o C and kPa), one mole of an ideal gas occupies L. The equation that converts the mass of the pollutant M p in grams to its equivalent volume V p in liters at standard temperature and pressure (STP) is: The equation that converts the mass of the pollutant M p in grams to its equivalent volume V p in liters at standard temperature and pressure (STP) is: For readings made at temperatures and pressures other than standard conditions, the standard volume, L, must be corrected. For readings made at temperatures and pressures other than standard conditions, the standard volume, L, must be corrected. Using the ideal gas law to make the corrections, Using the ideal gas law to make the corrections,

where, T 2 and P 2 are the absolute temperature and absolute pressure at which the readings are made. T 2 and P 2 are the absolute temperature and absolute pressure at which the readings are made. Then at absolute temperature and pressure (not STP), Then at absolute temperature and pressure (not STP), where, V p is the volume of pollutant when not in standard temperature and pressure (STP). V p is the volume of pollutant when not in standard temperature and pressure (STP).

Since ppm is a volume ratio, then we may write, Since ppm is a volume ratio, then we may write, where, V a is the volume of air at temperature and pressure of the reading, while V p is the volume of pollutant. V a is the volume of air at temperature and pressure of the reading, while V p is the volume of pollutant. Example No. 3: A sample of air was found to contain 80g/m 3 of SO 2. The temperature and pressure were 25 o C and kPa when the air sample was taken. What was the SO 2 concentration in ppm?