Air Pollution-Tropospheric Ozone
Air Pollution-Tropospheric Ozone
Good ozone and bad ozone Stratospheric ozone protect lives on Earth from harmful effects of uv radiation Tropospheric ozone Causing respiratory distress and eye irritation Destroying plants Producing cracks in rubber Ozone is a strong oxidant reacts with molecules containing C=C double bonds, forming epoxides
Good Ozone and Bad Ozone • Stratospheric ozone protect lives on Earth from harmful effects of UV radiation. • Tropospheric ozone: – Causing respiratory distress and eye irritation – Destroying plants – Producing cracks in rubber Ozone is a strong oxidant, reacts with molecules containing C=C double bonds, forming epoxides
Two types of air pollutants: primary vs secondary Primary pollutants: released directly from sources Examples: CO, So2, NOX Secondary pollutants: formed through chemical reactions of the primary pollutants and the constituents of the unpolluted atmosphere in the air. Example: 03
Two types of air pollutants: primary vs. secondary • Primary pollutants: released directly from sources – Examples: CO, SO2, NOx • Secondary pollutants: formed through chemical reactions of the primary pollutants and the constituents of the unpolluted atmosphere in the air. – Example: O3
Formation of ozone No2 is capable of absorbing visible light(<400 nm) to produce o NO2+h→NO+0 O+O2+M→03+M 2) No net o3 formation NO+O3→NO2+O2 (3) NO2+h→NO+0 O+O2+M→O2+M (2)03is (4) formed 千O2NO>NO2+OH RO2+NO→NO2+RO (5) Net of(1)+(2)+(4):RO2+02→03+RO
Formation of ozone NO2 + hv → NO + O (1) O + O2 + M → O3 + M (2) NO + O3 → NO2 + O2 (3) NO2 + hv → NO + O (1) O + O2 + M → O3 + M (2) HO2 . + NO→ NO2 + OH (4) RO2 . + NO → NO2 + RO. (5) No net O3 formation O3 is formed Net of (1)+(2)+(4): RO2. + O2 → O3 + RO. NO2 is capable of absorbing visible light (<400 nm) to produce O
Sources of RO2: Oxidation of hydrocarbons RH+OH→R·+H20 R·+02÷RO2 A single organic radical can produce many peroxy radicals by successive rounds of O2 combination and fragmentation
Sources of RO2. : Oxidation of hydrocarbons RH + OH → R . + H2O R . + O2 → RO2. A single organic radical can produce many peroxy radicals by successive rounds of O2 combination and fragmentation