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Air pollution

1. Chemistry (1)
CHE 011
Preparatory year
Lecture (3)
Air pollution
Ass. Prof./ HebaAbdEl Gawad
The Higher Institute of Engineering
Chemical Engineering Department
2022-2023

2. Pollution
Itisdefinedasthedischargeofanysubstance(contaminatesorpollutants)intotheenvironment
whichaffectsadversityqualityofenvironmentandcausingdamagetohumans,plantsand
animals.
Or,itisanyundesirablechangeinphysical,chemicalandbiologicalofcomponentof
environmentsuchasair,waterorsoilwhichcancauseharmfuleffectsonvariousformsoflifeor
property.
Pollutant
meansanysubstanceinsolid,liquidorgaseousstate,oranyplant,animalormicroorganismthat
isinjurioustohumanhealthortheenvironment.(directlyorindirectly)
Or,Itisanysubstancecausingharmfuleffectstoorganisms.

3. Classification of environmental pollution:
EnvironmentalPollutionmaybeclassifiedinto:
1.NaturalPollution:duetoEarthquakes,flood,drought,cyclone.
2.ArtificialPollution:duetohumanactivities(suchas,industries-
Agricultural-transportation…..etc.).

4. Thefollowingarethetypesofpollutionperceivedinourenvironment:
1.Waterpollution.
2.Thermalpollution.
3.Landpollution.
4.RadiationPollution.
5.Noisepollution.
6.Airpollution.
Types of pollution:

5. Effects of Environmental Pollution:
1.EffectsonHumans.
2.EffectsonAnimals.
3.EffectsonPlants.
4.EffectsontheEcosystem.

7. Air pollution
Itisdefinedasanintroductionofundesirablecontaminates
(pollutants)ofgas,smoke,dust,fume,mist,odor,orchemical
particulatesintheatmospherewhichareinjurioustohumanbeings,
plantsandanimals.
Oranyvisibleorinvisibleparticleorgasfoundintheairthatisnot
partoftheoriginal,normalcomposition.
Orconcentrationofforeignmatterinairinexcessivequantity
whichisharmfultothehealthofhuman,plantsandanimals.

8. SourcesofAirPollution:
Thesourcesofairpollutionaredividedintonaturalandman-made.
1.Naturalsourcesincludevolcaniceruptions,dust,storms--etc.,
2.Manmadesources(unnatural)(Artificial)includetransportations,fuel
combustionfromstationarysources(coal,woodandotherfuelsusedincars,
homes,andfactoriesforenergy),industrialprocessesandsolidwastesdisposal,
domesticburning,includesthepollutionfromships,planes,trainand
automobilesbuttheautomobileistheworstcontributortoairpollution
particularlytwowheelers.

9. Air pollutant: A substance in the air that can cause harm to humans and the
environment. [may be particulate matter: (solid or liquid) or gas]
Types of air pollutants:
Air pollutants can broadly classified into two types:
1.Primary pollutants
2.Secondary pollutants
Primary pollutants
Pollutants that are emitted directly from either natural events or from human
activities are called primary pollutants. The natural events are dust storms;
volcano etc. and human activities can be emission from vehicles, industrial wastes.

10. About90%ofglobalairpollutionisconstitutedbyfiveprimarypollutants.These
are
Carbonoxides(COandCO2)
Nitrogenoxides(nitricoxide,NOisproducedbycombustionandNO
2isproduced
fromtheoxidationofNO).
Sulphuroxides(producedwhencoalandfueloilareburned).
Hydrocarbons(Diversegroupoforganiccompoundsthatcontainonlyhydrogenand
carbonex:CH
4-methane).
Particulatematter,SPM(aerosols)(particlesofdifferentsizesandstructuresthatare
releasedintotheatmosphere.presentinmanysourcesincludingfossilfuels,dust,
smoke,fog,etc.).

11. Secondary pollutants
Primary pollutants when reacting with each other or from substances normally
found in the atmosphere; forms new pollutants called secondary pollutant.
For example:O
3, sulphuricacid, nitric acid, carbonic acid, hydrogen peroxide,
PAN (peroxyacetyl nitrate), etc.

12. Effect of air pollution:
1.Effectsonhumanhealth,
2.Effectsonanimalsandplants,and
3.Effectsonatmosphere
Effects on Human Health
[short term effects (Acute) & long-term effects (chronic)]
Acuteeffects:withintwenty-fourhoursofsuddenexposuretopollutedairillnesswouldoccur.
Chroniceffects:Thecause-and-effectrelationshipofairpollutionandchroniceffectsonhealthis
inawaydifficulttoproveduetolongtimecontactandaccumulationeffect.

13. Effects on animals and plants
Theimpactofairpollutiononanimalsismoreorlesssimilartothatonman.Chronicpoisoningresultsfrom
theingestionofforagecontaminatedwithatmosphericpollutants.Plantsdamagedbyozone,sulfurdioxide,&
acids.
Effects on atmosphere
Someoftheeffectsofairpollutiononatmosphericconditions,suchaseffectonozonelayer,greenhouse
effect(producingglobalwarming),etc.,havealreadybeendiscussed.Thereisanincreaseinthecarbon
dioxideconcentrationintheairduetoincreasedcombustionoffossilfuels.Carbondioxideabsorbsheat
stronglyandtheradiativecoolingeffectoftheearthisthusdecreased.
Therisingoftemperaturesandozoneholesaresomeoftheproblemswhichhaveattractedtheattentionof
thescientistsallovertheworld.Theseproblemsarenotrelatedtoanyregionoracountrybutarethe
globalproblemsandtheirimpactonworldclimatemaybehazardoustothewholeworld.Thelocal
weatherconditionsarehighlysusceptibletoairpollution.Itsimpactontemperature,humidity,rainfalland
cloudsisapparent.Duetoairpollution,visibilityalsoreduces.

14. Control of air pollution:
Todesignacertainsystemtocontrolairpollution,wemusthavedataabout:
1.Flowrate
2.Concentrationofpollutants
3.Physicalpropertiesofpollutants
4.Chemicalpropertiesofpollutants

16. Control of particulate solids

19. Anelectrostaticprecipitator(ESP)isdefinedasafiltrationdevicethatisusedtoremovefineparticleslike
smokeandfinedustfromtheflowinggas.Itisthecommonlyuseddeviceforairpollutioncontrol.
Removetheparticlesofsize<0.01µm.
C)Anelectrostaticprecipitator(ESP)

20. Itconsistsoftwosetsofelectrodes:positiveandnegative.Thenegativeelectrodesareintheformofawire
mesh,andthepositiveelectrodesareplates.Theseelectrodesareverticallyplacedandarealternateto
eachother.
Thegasborneparticlessuchasashareionizedbythehighvoltagedischargeelectrode.Theseparticles
areionizedtoanegativechargeandareattractedtopositivelychargedcollectorplates.

21. Inwetscrubbingprocesses,liquidorsolidparticlesareremovedfromagasstreambytransferring
themtoaliquid.Theliquidmostcommonlyusediswater.

23. Adsorptionisdesirableforcontaminantremovaldowntoextremelylow
levels.Condensationisbestforsubstanceshavingratherhighvapor
pressures.Incinerationisusedtoremoveorganicpollutantsandsmall
quantitiesofH
2S,CO,andNH
3.

28. Control of gaseous pollutants
SO2AirpollutedwithSO2ispumpedinadsorptiontowercontainactive
charcoalwhichadsorbSO2fromtheairandtheairfreeofSO2isleftaway
fromtheabsorber
NOXAircontainNoxandsulphuroxidesispumpedtoascrubberwhere
Mg(oH)2isfallingdownandthecleangasisleftaway.
H2SAircontainH2Sispumpedinabsorptiontowerwhileethanolamine
isfallingdownandcleanairisleftfromthetop.