광화학 스모그는 햇빛, 질소산화물(NOx), 휘발성 유기화합물(VOC)이 관련된 복잡한 일련의 반응을 통해 생성됩니다. 이 과정은 햇빛이 이산화질소(NO₂)를 일산화질소(NO)와 산소 원자(O)로 분해하면서 시작됩니다. 이렇게 생성된 자유 산소 원자는 분자 산소(O₂)와 결합하여 지표면 오존(O₃)을 형성하는데, 이는 스모그의 주요 구성 요소입니다.
광화학 스모그
1950
(설명을 위한 생성된 이미지입니다)
The formation of photochemical smog is a cyclical process driven by solar radiation. The cycle begins in the morning rush hour, when vehicles emit large quantities of nitrogen oxides (NOx) and volatile organic compounds (VOCs). Sunlight’s ultraviolet (UV) radiation provides the energy for the initial key reaction: the photolysis of nitrogen dioxide ([latex]NO_2 \\xrightarrow{h\nu} NO + O[/latex]). The highly reactive atomic oxygen (O) then quickly combines with diatomic oxygen ([latex]O_2[/latex]) to form ozone ([latex]O_3[/latex]): [latex]O + O_2 \\rightarrow O_3[/latex]. Normally, this ozone would be destroyed by reacting with the nitric oxide (NO) produced in the first step, reforming [latex]NO_2[/latex] and [latex]O_2[/latex] in a null cycle. However, the presence of VOCs disrupts this balance.
VOCs react with hydroxyl radicals (OH) in the atmosphere to form peroxy radicals ([latex]RO_2[/latex]). These peroxy radicals are highly effective at oxidizing NO to [latex]NO_2[/latex] without consuming an ozone molecule: [latex]RO_2 + NO \rightarrow RO + NO_2[/latex]. This reaction rapidly regenerates [latex]NO_2[/latex], which can then be photolyzed again to produce more ozone, while also preventing NO from depleting the existing ozone. This leads to a net accumulation of ozone throughout the day, with concentrations typically peaking in the afternoon. The complex mixture also includes other harmful secondary pollutants like peroxyacetyl nitrate (PAN), aldehydes, and nitric acid, creating the characteristic hazy, irritant-laden air known as smog.
UNESCO Nomenclature: 2501
대기과학
유형
화학 공정
분열
상당한
용법
널리 사용됨
전구체
- discovery of ozone by christian friedrich schönbein
- understanding of chemical kinetics and reaction mechanisms
- development of the internal combustion engine and widespread use of automobiles
- identification of volatile organic compounds and nitrogen oxides as pollutants
- arie jan haagen-smit’s research linking ozone to plant damage in los angeles
응용 프로그램
- formulation of low-voc paints, solvents, and consumer products
- vehicle emission standards (e.g., euro standards, us epa standards)
- air quality forecasting models that predict high ozone days
- vapor recovery systems at gasoline stations
- development of alternative fuel vehicles with lower nox and voc emissions
특허:
NA
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Related to: photochemical smog, ground-level ozone, nitrogen oxides, volatile organic compounds, VOC, NOX, sunlight, atmospheric chemistry, secondary pollutant, peroxyacetyl nitrate.
역사적 맥락
광화학 스모그
(날짜를 알 수 없거나 관련이 없는 경우, 예를 들어 "유체역학"의 경우, 주목할 만한 등장 시기를 대략적으로 추정하여 제공합니다.)
