Environmental Chemistry Tropospheric chemistry

Presentation on theme: "Environmental Chemistry Tropospheric chemistry"— Presentation transcript:

1 Environmental Chemistry Tropospheric chemistry
대류권화학 Tropospheric chemistry 1. 광화학스모그 ( smog) - 가스성분의 농도표기법 및 변환 (concentration) 1) mol/cm3 2) ug/m3 3) mol/liter (mol/dm3) 4) ppmv, ppbv 농도변환의 예 1 SO2 (Mw 64.1g)in air 320ug/m3  ? ppb 320ug  3.011018 molecules of SO2 1m3  2.451025 molecules of SO2 = 2.45 1016 billion molecules 농도변환의 예 2 40ppb O3  ? ug/cm3  ? mg/m3 환경화학 37

2 Environmental Chemistry
광화학스모그 기본반응 VOCs + NO + ( )  O3, HNO3, organics (organic ) 환경화학 38

3 Environmental Chemistry
1. 광화학반응의 발생요건 (conditions for phtochemical smog) 1) 충분한 교통량, traffic ( ) 2) 충분한 일조량, ( ), 적정온도 (temp) 3) 공기정체, stable atmospheric condition 환경화학 39

4 Environmental Chemistry
2. 광화학반응 (photochemical reactions) 1) NOx의 발생 N2 + O2  2NO 2NO + O2  2NO2 NO + O3  NO2 + O2 NO + ROO•  NO2 + RO• 2) 오존과 hydroxyl free radical의 발생 NO2 + hν(<400nm)  ( ) O + O2 + M  ( ) O3 + hν(<315nm)  O2* + O* O* + H2O  2HO•__________ NO2 + H2O  2HO• + NO 3) hydroxyl radical 발생반응2 NO + NO2 + H2O  2HONO 2HONO + hν(<400nm)  2NO + 2HO• 환경화학 40

5 Environmental Chemistry
광화학반응 (계속) 4) 탄화수소(hydrocarbon)의 산화반응 RCH3 + OH•  RCH2 + H2O RCH2 + O2 + M  RCH2OO• + M RCH2OO• + NO  RCH2O• + NO2 RCH2O• + O2  RCHO + HOO• HOO• + NO  HO• + NO2 RCH3 + 2O2 + 2NO  ( ) + 2NO2 + H2O 5) hydroxyl free radical의 소멸반응 HO• + NO2 + M  HNO3 2HOO•  H2O2 + O2 HO• + HOO•  H2O + O2 6) 광화학스모그 2차반응 CH3CHO + OH•  CH3CO + H2O CH3CO + O2 + M  CH3C(O)OO• CH3C(O)OO• + NO2  CH3C(O)OONO2 peroxyacetic acid nitric anhydride peroxyacetyl nitrate ( ) 환경화학 41

6 Environmental Chemistry
광화학반응 (계속) 7) Alkene (unsaturated hydrocarbon)의 산화반응 R R’ R R’ C = C + HO•  HO  C  C H H H H R R’ R R’ HO  C  C O2  HO  C  C  O  O• H H H H R R’ HO  C  C  O  O• + NO  R R’ H H HO  C  C  O• + NO2 H H R R’ R R’ HO  C  C  O•  C  H + O = C H H HO H R R C  H + O2  C = O + HOO• HO H 환경화학 42

7 Environmental Chemistry
3. NO의 제거, 3원 촉매 1) 환원실(reduction chamber): Rd 금속촉매 H2O + fuel  H2 2NO + 2H2  ( ) 2) 산화실(oxidation chamber): Pt/Pd 금속촉매 2CO + O2  2CO2 fuel + O2  ( ) 환경화학 43

8 Environmental Chemistry
3. 산성비 (acid rain) What goes up must come down, though in the acid rain, what comes down is worse than what went up! 환경화학 44

9 Environmental Chemistry
1) 산성비의 기준 pH 대기중 CO2 농도: 약 350 ppmv CO2 + H2O  H2CO3(aq) H2CO3(aq)  HCO3 +H+ pH = ( ) 따라서 pH<( ) 일 경우 acid rain 통상 pH가 5 미만일 때 acid rain이라 함 환경화학 45

10 Environmental Chemistry
2) 산성비의 산성성분 ( ), H2SO4 3) HNO3의 생성 Daytime NO2• + HO• + M  HNO3 + M Night-time NO2• + O3  NO3• + O2 NO3• 축적:야간 NO2• + NO3•  N2O5 N2O5 + H2O  2HNO3 HNO3의 제거 -( ) deposition -reaction with ammonia NH3 + HNO3  NH4NO3 환경화학 46