《大学化学》课程PPT教学课件（英文版讲稿）Chapter 17 Air resources

Chapter 17 Air resources The atmosphere layer is very thin compared to the size of the earth

Chapter 17 Air resources • The atmosphere layer is very thin compared to the size of the Earth

17.1 The earths atmosphere is a mixture of gases Our atmosphere is a result of actions of both heat and gravity ※:※ (a)Atmospherewith gravity but no (a) Atmosphere with solar heat but(a) Atmosphere with solar heat and solar heat: molecules lie on the no gravity: molecules escape into gravity: molecules reach high earth's surface outer space altitudes but are prevented from escaping into outer space Fig 17. 1 our atmosphere is a result of the actions of both solar heat and gravity

17.1 The Earth’s atmosphere is a mixture of gases. Our atmosphere is a result of actions of both heat and gravity (a) Atmosphere with gravity but no solar heat: molecules lie on the earth’s surface (a) Atmosphere with solar heat but no gravity : molecules escape into outer space (a) Atmosphere with solar heat and gravity : molecules reach high altitudes but are prevented from escaping into outer space Fig 17.1 our atmosphere is a result of the actions of both solar heat and gravity

Atmosphere is divided into layers ionosphere 350km Mesosphere 90 km Fig 17.2 the two 50 km stratosphere lowest atmospheric Tropopause layers-troposphere 18 km and stratosphere Troposphere 14 km Earth

Atmosphere is divided into layers. Fig 17.2 the two lowest atmospheric layers-troposphere and stratosphere

17.2 Human activities have increased air pollution ·∨ olcano Fig 17. 3 the cloud of sulfur dioxide generated by the June 15, 1991 eruption of Mount Pinatubo reached India in four days. (the black strips are where satellite data are missing. ) by July 27, the sulfur dioxide cloud had traveled around the globe

17.2 Human activities have increased air pollution • Volcano Fig 17.3 the cloud of sulfur dioxide generated by the June 15,1991, eruption of Mount Pinatubo reached India in four days. (the black strips are where satellite data are missing.) by July 27, the sulfur dioxide cloud had traveled around the globe

Aerosol(烟、雾、气凝胶) and particulates facilitate chemical reactions involving pollutants Aerosol co O co H2CO NO →NO2 Solid particle 001mm Hydrocarbon Hydrocarbons NO+ O Aldehydes, NO HaSO SO dehyde sO Fig 17. 4(a) micrograph of aerosols in the atmosphere. b) an aerosol is the site of many chemical reactions involving pollutants. Water surrounding the solid particle attracts airborne molecules that them readily react in aqueous solution before being released back into the atmosphere

Aerosol (烟、雾、气凝胶) and particulates facilitate chemical reactions involving pollutants Aerosol Fig 17.4 (a) micrograph of aerosols in the atmosphere. (b) an aerosol is the site of many chemical reactions involving pollutants. Water surrounding the solid particle attracts airborne molecules that them readily react in aqueous solution before being released back into the atmosphere

Removal of aerosol and particulates scrubbing liquid Fig 17.5 during scrubbing compressed air of industrial gaseous hybrid nozzle effluents a fine mist of cleaned gas water captures and off-gas removes solid particles that have diameters as small as 0.001 millimeter venturi throat cyclon droplet separator sun

Removal of Aerosol and particulates Fig 17.5 during scrubbing of industrial gaseous effluents, a fine mist of water captures and removes solid particles that have diameters as small as 0.001 millimeter

(+)r voltage 1(-) Fig 17.6(a)particulates in industrial gaseous Gas effluents become electrode negatively charged by an electrode and are attracted Without electrostatic to the positively charged particles precipitator wall of the electrostatic precipitator. Once it touches the wall a particulate loses its charge and falls into a collection bin. (b) Gas and smokestacks with and suspende without electrostatic d particles To collection bin precipitators With electrostatic precipitat

Fig 17.6 (a) particulates in industrial gaseous effluents become negatively charged by an electrode and are attracted to the positively charged wall of the electrostatic precipitator . Once it touches the wall, a particulate loses its charge and falls into a collection bin. (b) smokestacks with and without electrostatic precipitators Without electrostatic precipitator With electrostatic precipitator To collection bin electrode particles (+) voltage (-) Gas and suspende d particles Gas

There are two kinds of smog Industrial and photochemical Industrial smog: sulfur dioxide and sulfuric acid Photochemical smog: nitrogen oxides, ozone and hydrocarbons from internal combustion engine 50 )40 NO Fig 17. 8 the average daily concentration of O130 nitrogen monoxide z120 itrogen dioxide, and ozone in Los Angeles 10 night sunrise noon sunset ht ppm= parts per million Catalytic converters reduce automobile emissions

There are two kinds of smog: Industrial and photochemical Industrial smog: sulfur dioxide and sulfuric acid Photochemical smog: nitrogen oxides, ozone and hydrocarbons from internal combustion engine. Catalytic converters reduce automobile emissions Fig 17.8 the average daily concentration of nitrogen monoxide, nitrogen dioxide, and ozone in Los Angeles *ppm = parts per million night sunrise noon sunset night NO,NO 2,O 3(ppm)

17.3 Stratospheric ozone protects the Earth from UV radiation O3+UV—03+heat Fig 17.17 false-color image Earth Probe TOMS Total Ozone September 16, 2000 of ozone levels over the Northern Hemisphere, recorded by NASA's total- ozone mapping spectrometer(TOMS). Blue and purple areas are areas of ozone depletion; red and green areas are areas of higher-than- normal ozone levels 0oonu超3+0

17.3 Stratospheric ozone protects the Earth from UV radiation • O3 + UV O3 + heat Fig 17.17 false-color image of ozone levels over the Northern Hemisphere, recorded by NASA’s total￾ozone mapping spectrometer (TOMS). Blue and purple areas are areas of ozone depletion; red and green areas are areas of higher-than-normal ozone levels

17.4 Air pollution may result in global warming Short-wavelength visible light from the sun is transmitted through the glass Fig 17.18 glass acts as Long-wavelength frared radiation is a one-way valve, letting not transmittedout visible light in and through the glass preventing infrared and is trapped inside energy from exiting The Greenhouse Effect Some of the intrared radiation passes rough the atmosphere, and some is Fig 17.19 the greenhouse effect in solar radiaton absorbed and re emitted n all directions by greenhouse gas the earth s atmosphere visible light is reflected by the molecules. The effect of this is to war earth and the the earth's surface and the lowe from the sun is absorbed by the atmosphere atmosphere. ground, which then emits infrared radiation Carbon dioxide, water vapor, and other greenhouse gases in the atmosphere absorb and re Most radiation is absorb by the earth's surtace emit heat that would otherwise be and warms it hom the ear radiated from the earth into space

17.4 Air pollution may result in global warming Fig 17.18 glass acts as a one-way valve, letting visible light in and preventing infrared energy from exiting. Fig 17.19 the greenhouse effect in the earth’s atmosphere. Visible light from the sun is absorbed by the ground, which then emits infrared radiation. Carbon dioxide, water vapor, and other greenhouse gases in the atmosphere absorb and re￾emit heat that would otherwise be radiated from the earth into space Long-wavelength infrared radiation is not transmitted out through the glass and is trapped inside Short-wavelength visible light from the sun is transmitted through the glass