diossido di carbonio - techintroduce

Abriefhistoryofresearch

Inprimitivesociety,primitivepeopleperceivetheexistenceofcarbondioxideintheirdailylife,butduetothelimitationofhistoricalconditions,theylookattheinvisibleandintangiblecarbondioxide.Chengisamonsterthatkillswithoutleavingatrace,notasubstance.

Inthe3rdcentury,ZhangHua(232-300)duringtheWesternJinDynastyinChinarecordedakindofburningwhitestone(CaCO₃)Thegasproducedintheprocessofmakingwhiteash(CaO),whichisnowthelimekilngasusedinindustryfortheproductionofcarbondioxide.

Atthebeginningofthe17thcentury,theBelgiandoctorHelmont(ieJanBaptistavanHelmont,JanBaptistavanHelmont,1580-1644)discoveredthatafterburningcharcoal,inadditiontoproducingashesSomeinvisibleandintangiblesubstancesareproduced,andexperimentshaveconfirmedthatthiskindofcarbondioxide,whichhecalledthe"EssenceoftheForest",isanon-combustiblegas,andthatcarbondioxideisagas;itisalsofoundthatcandlesareinthegas.Thisisthefirstdiscoveryoftheinertnatureofcarbondioxide.Soonafter,theGermanchemistHoffmann(ieFriedrichHoffmann,1660-1742)studiedthecarbondioxidegashecalled"spiritusmineralis"andinferredforthefirsttimeThecarbondioxideaqueoussolutionisweaklyacidic.

In1756,theBritishchemistBlack(ieJosephBlack,JosephBlack,1728-1799)wasthefirsttoquantitativelystudythecarbondioxidegashecalled"fixedair".Afterthat,itwascalled"fixedair"foraperiodoftime.

In1766,BritishscientistCavendish(ieHenryCavendish,HenryCavendish,1731-1810)successfullycollectedthe"fixedair"bythemercurytankmethod,andusedphysicalmethodsThespecificgravityandsolubilityweremeasured,anditwasalsoprovedthatitisthesameasthegasexhaledbyanimalsandthegasproducedbyburningcharcoal.

In1772,theFrenchscientistLavoisier(namelyAntoine-LaurentdeLavoisier,Antoine-LaurentdeLavoisier,1743-1794)etc.usedalargeflamemirrortocondenseandheatthemercury.Thediamondintheglasscoveronthetroughisfoundtoburn,andtheproductis"fixedair".Inthesameyear,whenthescientistPriestley(ieJosephPriestley,JosephPriestley,1733-1804)studiedfermentedgas,hefoundthatpressureisbeneficialtothedissolutionof"fixedair"inwater,andtheincreaseintemperatureisnotconducivetoitsdissolution..Thisdiscoveryallowscarbondioxidetobeusedtoartificiallymakecarbonatedwater(soda).

In1774,theSwedishchemistBergman(i.e.TorbernOlofBergman,TorbernOlofBergman,1735-1784)describedinhispaper"ResearchonFixedAir"Hisresearchresultsonthedensityof"fixedair",solubilityinwater,effectonlitmus,conditionofbeingabsorbedbyalkali,existenceintheair,anddissolutionofmetalliczincandironbyaqueoussolution.

In1787,Lavoisierdescribedthe"fixedair"producedbyburningcharcoalinoxygen,confirmingthatthe"fixedair"iscomposedofcarbonandoxygen,becauseitItisagasandwasrenamed"carbondioxide".Atthesametime,Lavoisieralsomeasuredthemassratioofcarbonandoxygen(carbonaccountedfor23.4503%,oxygenaccountedfor76.5497%),revealingthecompositionofcarbondioxideforthefirsttime.

In1797,BritishchemistTennant(ieSmithsonTennant,SmitbsonTennant,1761-1815,alsotranslated"Tainet"etc.)usedanalyticalmethodstodetermine"Fixedair"contains27.65%carbonand72.35%oxygen.

In1823,BritishscientistFaraday(ieMichaelFaraday,MichaelFaraday,1791-1867)discoveredthatpressurizationcanliquefy"carbonicacidgas".Inthesameyear,FaradayandDavid(namelyHumphryDavy,1778-1829,alsotranslatedas"DiBi")liquefied"carbonicacidgas"forthefirsttime.

In1834or1835,theGermanTyrolean(ieAdrianJean-PierreThilorier,Adrien-Jean-PierreThilorier,1790-1844,andTranslated"Tilorel","Dilauriyari","Chilorie",etc.)successfullyproduceddryice(solidcarbondioxide).

In1840,theFrenchchemistDumas(namelyJean-BaptisteAndréDumas,Jean-BaptisteAndréDumas,1800-1884)putaccuratelyweighedcontentPurecarbongraphiteisburnedinsufficientoxygen,andtheresulting"fixedair"isabsorbedbypotassiumhydroxidesolution,andthemassfractionratioofoxygentocarboninthe"fixedair"iscalculatedtobe72.734:27.266.Earlier,Avogadro(i.e.AmedeoAvogadro,AmedeoAvogadro,August9,1776-July9,1856)putforwardthehypothesisin1811-"AtthesametemperatureandUnderpressure,anygasofthesamevolumecontainsthesamenumberofmolecules."Chemistscombinetheatomicweightsofoxygenandcarbontoarriveatthe"fixedair"ofthenumberofoxygenandcarbonatoms.Thesimpleintegerratiois2:1.BasedonthehypothesisputforwardbyAvogadroin1811,themolecularweightof"fixedair"wasmeasuredtobe44throughexperiments,andthechemicalformulaof"fixedair"wasCO₂,whichisthesameasthischemicalformula.Thecorrespondingnameis"carbondioxide".

In1850,theIrishphysicalchemistAndrews(thatis,ThomasAndrews,ThomasAndrews,1813-1885)begantostudythesupercriticalphenomenonofcarbondioxide,andin1869measuredthecarbondioxideTwocriticalparameters:thesupercriticalpressureis7.2MPa,andthesupercriticaltemperatureis304.065K(therecognizedvaluesofthetwoin2013were7.375MPaand303.05K,respectively).

In1896,theSwedishchemistArrhenius(SvanteAugustArrhenius,SvanteAugustArrhenius,1859-1927)pointedoutbycalculationthattheatmosphereAdoublingoftheconcentrationofcarbondioxidecanincreasethesurfacetemperatureby5to6°C.

Between1950and1952,theSovietUnion’sLyubavsky(KBЛюбавский),Novorzhlov(HMНовожилов)andJapan’sHarujiroSekiguchieachstudiedtheuseofaprotectivegasforcarbondioxide.Usedweldingwire,andproposedanewmetallurgicalprogramforweldingsteel.Subsequently,in1953,Ljubavskyandothersinventedcarbondioxidegasshieldedwelding.

Molecularstructure


CO₂molecularstructure	CO₂bondingprocess

CO₂Themolecularshapeisstraight,Itsstructurewasoncethoughttobe:O=C=O.Butthecarbon-oxygenbondbondlengthintheCO₂moleculeis116pm,whichisbetweenthecarbon-oxygendoublebond(thebondlengthis124pm)andthecarbon-oxygentriplebond(thebondlengthis113pm),soCO2hasacertaindegreeoftriplebondcharacteristics.

ModernscientistsgenerallythinkthatthecentralcarbonatomofCO₂moleculeadoptssphybridization,andthetwosphybridorbitalsarerespectivelyconnectedwiththe2porbitalsoftwooxygenatoms(containingoneelectron).)Overlappingtoform2σbonds,theporbitalsperpendiculartoeachotheronthecarbonatomsandtheparallelporbitalsofthe2oxygenatomsrespectivelyform2largeπbonds.

Physicalandchemicalproperties

Physicalproperties

Carbondioxideisacolorlessandodorlessgasatroomtemperatureandpressure,anditissolubleinmostorganicsolventssuchaswaterandhydrocarbons.Thephysicalconstantsareasfollows:

Properties

Conditionsorsymbols

Unit

Data

tr>

Meltingpoint	527kPa	Celsius(°C)	-56.6
Boilingpoint		Celsius(℃)	-78.5
Relativedensity	-79℃,water=1		1.56
Relativevapordensity	Air=1		1.53
Saturatedvaporpressure	-39℃	kPa(kPa)	1013.25
Criticaltemperature		Celsius(°C)	31.3
criticalpressure		MegaPascal(MPa)	7.39
Octanol/waterpartitioncoefficient			0.83
Refractiveindex	12.5～24℃		1.173～1.999
molarrefractiveindex			6.98
Viscosity	21℃，5.92MPa	mPa·s	0.0697
Evaporationheat p>	Sublimation	kJ/mol(kJ/mol)	25.25
Heatoffusion		kJ/mol(kJ/mol)	8.33
Generateheat		kJ/mol(kJ/mol)	394.40
Specificheatcapacity	20℃,constantpressure	kJ/kg·Kelvin[kJ/(kg·K)]	2.8448
Vaporpressure	5.9～14.9℃	MegaPascal(MPa)	4.05～5.07
Thermalconductivity	12～30℃	WattspermeterKelvin[W/(m·K)]	0.10048～83.74×10^-7
bodyexpansioncoefficient	-50～0℃	perKelvin(K^-1)	0.00495
0～20ºC	PerKelvin(K^-1)	0.00991
Molevolume		Milliliterpermole(mL/mol)	44.7
Isometricspecificvolume	90.2K		60.9
surfacetension		Dynepercentimeter(dyne/cm)	3.4
Polarizationrate	10^-24cm³		2.76

(Reference:)

Chemicalproperties

Carbondioxideisoneofthecarbonandoxygencompounds.Itisaninorganicsubstance,non-flammableandusuallynotItsupportscombustionandisnon-toxicatlowconcentrations.Itisalsoanacidicanhydrideofcarbonicacid.Itisanacidicoxideandhasthesamepropertiesasanacidicoxide.Thevalenceofcarbonis+4,whichisthehighestvalenceofcarbon.Therefore,carbondioxideisoxidizingandnon-reductive,butoxidizing.Notstrong.

1.Generalityofacidicoxides

1-1.Reactwithwater

Carbondioxidecandissolveinwaterandreactwithwatertoformcarbonicacid.Unstablecarbonicacidiseasilydecomposedintowaterandcarbondioxide.Thecorrespondingchemicalreactionequationis:

;

1-2.Reactwithalkalineoxide

Undercertainconditions,carbondioxideItcanreactwithalkalineoxidestoformcorrespondingsalts,suchas:

;

1-3.Reactwithalkali

①andCalciumHydroxideReaction

Addingcarbondioxidetotheclarifiedlimewaterwillmaketheclarifiedlimewaterturbidandformcalciumcarbonateprecipitation(thisreactionOftenusedtotestcarbondioxide),thecorrespondingchemicalreactionequationis:

Whencarbondioxideisexcessive,calciumbicarbonateisformed:

Thefirststep:;

Thesecondstep:;

Generalequation:.

Becauseofthehighsolubilityofcalciumbicarbonate,ifcarbondioxideisaddedtotheturbidlimewaterforalongtime,itcanbefoundthattheprecipitationgraduallydisappears.

②Reactionwithsodiumhydroxide

Carbondioxidewilldeterioratecausticsoda.Thecorrespondingchemicalreactionequationis:

Whencarbondioxideisexcessive,sodiumbicarbonateisformed:

Firststep:;

Secondstep:;

Generalequation:.

2.Weaklyoxidizing

2-1.Carbonelementreduction

Underhightemperatureconditions,carbondioxidecanreactwithcarbonelementstoformcarbonmonoxide.Thecorrespondingchemicalreactionequationis:

2-2.Magnesiumelementreduction

Underlightingconditions,magnesiumbarsItcanburnincarbondioxide,andthecorrespondingchemicalreactionequationis:

2-3.Hydrogenationreduction

CarbondioxideandhydrogenwillAseriesofreactionstogeneratemethanol,carbonmonoxideandmethaneoccur.Thechemicalreactionequationsofseveralreactionsare:

;

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2-4.Electrochemicalreduction

TheelectrochemicalreductionofcarbondioxideisaElectricenergyreducescarbondioxideatthecathodeoftheelectrolyticcellandoxidizeshydroxideionstooxygenattheanodeoftheelectrolyticcell.Sincethereductionofcarbondioxiderequiresahighactivationenergy,thisprocesscanonlybeachievedafteracertainhighvoltageisapplied.Thedegreeofhydrogenprecipitationreactionincreaseswiththeincreaseofvoltage,whichwillinhibitthereductionofcarbondioxide.Therefore,theefficientreductionofcarbondioxiderequiresasuitablecatalyst,sothattheelectrochemicalreductionofcarbondioxideisoftenanelectrocatalyticreductionprocess.Thesimplemechanismofthisprocessis:(1)Electrolyticcellcathode:Intheinitialstage,carbondioxideisadsorbedonthesurfaceofthecathodecatalysttoformanintermediateproduct(reactionformula①);thenelectronsaretransferredundertheactionofthepotentialdifferencebetweenthetwoelectrodes,andthenumberoftransfersmaybeItis2,4,6,8,12.Thereductionproductmaybecarbonmonoxide,formate,formicacid,etc.dependingonthenumberofelectrontransfers(reactionformula②-④).⑵Anodeofelectrolysiscell:Hydrogenevolutionreactionoccursintheaqueoussolutiontoproducehydrogen(reactionformula⑤,⑥).

①

②

③

④

⑤

⑥

3.Reactwithperoxide

Carbondioxidecanreactwithsodiumperoxide(Na₂O₂)toformsodiumcarbonate(Na₂CO₃)andoxygen(O₂),thecorrespondingchemicalreactionequationis:.

4.ReactwithGrignardreagent

Underacidicconditions,carbondioxidecanreactwithGrignardreagentinanhydrousethertoformcarboxylicacid,thecorrespondingchemistryThereactionequationis:

Description:Intheformula,Risanaliphatichydrocarbongrouporanaromatichydrocarbongroup,andXisahalogen.

5.Intercalationreactionwithepoxycompounds

Carbondioxidecanreactwithepoxycompoundstoformcycliccarbonatesundertheactionofelectrocatalysis,correspondinglyThechemicalreactionequationis:

6.Preparationofdiamond(replacementreaction)

At440℃(713.15K)and800atmospheres(about808MPa)Undertheconditionof),carbondioxidecanreactwithsodiummetaltoproducediamond,andthecorrespondingchemicalreactionequationis:.

7.Thedarkreactionofphotosynthesis

Carbondioxideparticipatesinthedarkreactionofphotosynthesisandisanindispensablerawmaterialforphotosynthesisofgreenplants.Theprocessiscalled"carbondioxidefixation",andthecorrespondingchemicalreactionequationis:

Explanation:C₅intheformulais1,5-Ribulosediphosphate,2C₃is2moleculesof3-phosphoglycerate.

Waysofproduction

Carbondioxideisapartoftheatmosphere(0.03%-0.04%ofthetotalvolumeoftheatmosphere).Itisabundantinnature.Themainwaysofproductionareasfollows:①Organicmatter(includinganimalsandplants)canreleasecarbondioxideintheprocessofdecomposition,fermentation,decayanddeterioration.②Duringthecombustionofpetroleum,paraffin,coal,andnaturalgas,carbondioxideisalsoreleased.③Petroleumandcoalalsoreleasecarbondioxideduringtheproductionofchemicalproducts.④Allfecesandhumicacidcanalsoreleasecarbondioxideduringfermentationandmaturation.⑤Allanimalsmustbreatheinoxygenandexhalecarbondioxide.

Preparationmethod

Industrialpreparation

Calcinationmethod

Thecarbondioxidegasproducedintheprocessofhigh-temperaturecalcinationoflimestone(ordolomite)iswashed,impurity-removed,andcompressedtoproducecarbondioxidegas:

Fermentationgasrecoverymethod

Waterwashing,impurityremoval,compression,toobtaincarbondioxidegas.

By-productgasrecoverymethod

Ammonia,hydrogen,andsyntheticammoniaareoftenproducedintheproductionprocessTheprocessofdecarburization(removalofcarbondioxideinthegasmixture)allowsthecarbondioxideinthemixedgastobeabsorbedunderpressureandheatedunderreducedpressuretoobtainhigh-puritycarbondioxidegas.

Adsorptionexpansionmethod

Usually,by-productcarbondioxideisusedasrawmaterialgas,andadsorptionexpansionisusedThemethodextractshigh-puritycarbondioxidefromtheadsorptionphase,andcollectstheproductwithacryogenicpump;itcanalsobepreparedbytheadsorptionrectificationmethod.Theadsorptionrectificationmethodusessilicagel,3Amolecularsieveandactivatedcarbonasadsorbentstoremovesomeimpurities.Itcanbepreparedafterrectification.High-puritycarbondioxideproducts.

CharcoalKilnMethod

ItisrefinedfromthegasobtainedfromthecarbonkilnkilngasandmethanolcrackingGetcarbondioxide.

Preparationbylaboratory

Preparationbyreactionofmarbleanddilutehydrochloricacid

Theformula

Thelaboratoryproducescarbondioxide,marbleanddilutehydrochloricacid.Bothtypesofsodaarenotused,andthespeedistoofasttocontrol.

Withoutsulphuricacidhydrochloricacid,magnesiumsaltisnotascheapascalciumsalt.Nitricacidiseasytodecomposewhenexposedtolight.

Reactionproducts

Marbleorlimestone(themaincomponentisCaCO_₃)anddilutehydrochloricacid.(Laboratoryproductionofcarbondioxide,marbleanddilutehydrochloricacid)

Reactionprinciple

Reactionequation:

Preparationdevice

Solid-liquidnormaltemperaturetype(pictured).

Collectionmethod

Becausecarbondioxidehasahigherdensitythanair,itissolubleinwaterandcanreactwithwater,theupwardairexhaustmethodisadopted.

Inspectionmethod

Pourthegeneratedgasintoclarifiedlimewater.Thelimewaterbecomesturbid,whichprovesthatthegasiscarbondioxide.

Methodoffullinspection

Theburningwoodstickisusedatthemouthofthegascylinder(cannotbeinsertedintothebottle).Iftheflamegoesout,itisprovedSetfull.

Precautions

①Thehydrogenchloride(HCl)gasthatmayvolatilizeduringthereactioncanpassthroughsaturatedsodiumbicarbonate(NaHCO₃)Thesolutionremovesthehydrogenchloridegasinthegeneratedgas.

②Ifnecessary,agasscrubberfilledwithconcentratedsulfuricacidcanbeusedtoremovewatervaporinthegeneratedgas.

③Cannotreactwithcalciumcarbonateandconcentratedhydrochloricacid.Reason:Concentratedhydrochloricacidiseasytovolatilizealargeamountofhydrogenchloridegas,sothatsodiumbicarbonatecannotbecompletelyremoved,andthepurityofthecarbondioxideproducedwilldecrease.

carbon dioxide

④Inthelaboratory,marble(CaCO₃)isreactedwithdilutehydrochloricacidtoproducecarbondioxide.

⑤Can’tuseNa₂CO₃(soda)andNaHCO₃(bakingsoda)insteadofCaCO₃Itreactswithhydrochloricacidtoproducecarbondioxide.Reason:Na₂CO₃andNaHCO₃reacttoofastwithhydrochloricacid,Theproducedcarbondioxideescapesquickly,whichisnoteasytocontrolandeasytooperate.(Neitherofthesetwokindsofsodaisused,andthespeedistoofasttocontrol)

⑥Dilutesulfuricacidcannotbeusedinsteadofhydrochloricacid.Reason:thereactionofdilutesulfuricacidwithmarble(CaCO₃)willgeneratemicroTheprecipitationofcalciumsulfate(CaSO₄)dissolvedinwatercoversthesurfaceofthemarble,hinderingthereactionfromproceeding,andmakingthereactionveryslow.(Donotusesulfuricacidinsteadofhydrochloricacid)

⑦CannotuseMgCO₃(magnesiumsalt)insteadofCaCO₃(calciumsalt),Reason:AlthoughMgCO₃reactssimilarlywithhydrochloricacidandCaCO₃withhydrochloricacid,becauseMgCO₃hasfewersources,itisnotasgoodasCaCO₃Cheapandeasytoget.(Magnesiumsaltisnotascheapascalciumsalt)

⑧Nitricacidcannotbeusedinsteadofhydrochloricacid.Thereason:nitricacidiseasytodecomposewhenexposedtolight().Ifnitricacidisusedinsteadofhydrochloricacid,theobtainedCOTherewillbeasmallamountofNO₂andO₂in₂.Inaddition,nitricacidismoreexpensivethanhydrochloricacid,sonitricacidisusuallynotusedinsteadofhydrochloricacid.(Nitricacidiseasytodecomposewhenexposedtolight)

⑨Becausecarbondioxidecanextinguishthefire,aburningmatchcanbeplacedatthemouthofthegascylinderforinspection.Iftheflamegoesout,itprovesthatthegascylinderhasbeenfilledwithcarbondioxide.(Identifythatmatchesarenotcombustible)

Heattodecomposesodiumbicarbonatetoprepare

Afterthesodiumbicarbonateisfullydried,itisputintoahardglasstube,andthemouthofthetubeisfilledwithglasswoolandthensealed,andvacuumisdrawnwithanairpump.Then,heatingdecomposessodiumbicarbonate.Thefirstcarbondioxidecanbereleased.Thegasproducedbythedecompositionneedstobeintroducedintoanice-cooledpipetocondensethewatervaporinthegas,andthenthegasisintroducedintoU-shapedtubescontainingcalciumchlorideandphosphoruspentoxidetodrythem.At100°C,thedecompositionpressureofsodiumbicarbonateis97.458kPa,andat120°Citis166.652kPa.

Otherpreparationmethods

Whenbakingsoda(themaincomponentissodiumbicarbonate)andwhitevinegararemixedtogether,ametathesisreactionoccursandcarbondioxidegasisreleased.Thecorrespondingchemicalreactionequationis:

Mainapplications

High-puritycarbondioxideismainlyusedintheelectronicsindustry,medicalresearchandclinicaldiagnosis,carbondioxidelasers,calibrationgasfortestinginstrumentsandthepreparationofotherspecialmixedgas.Itisusedasaregulatorinthepolymerizationreaction.

Solidcarbondioxideiswidelyusedinrefrigerateddairyproducts,meat,frozenfoodandotherfoodsthatareperishableintransit.Itisusedasarefrigerantinmanyindustrialprocesses,suchascrushingheat-sensitivematerials,rubberpolishing,andmetalColdprocessing,shrinkassemblyofmechanicalparts,vacuumcoldtraps,etc.

Gaseouscarbondioxideisusedforcarbonizationofsoftdrinks,pHcontrolinwatertreatmentprocesses,chemicalprocessing,foodpreservation,inertprotectioninchemistryandfoodprocessing,weldinggas,plantgrowthstimulant,andhardeningincastingMoldsandcoresandusedinpneumaticdevices,andalsousedasadiluentforsterilizinggas(thatis,usingamixtureofethyleneoxideandcarbondioxideasasterilization,insecticide,andfumigant.Itiswidelyusedinmedicalappliances,packagingmaterials,andclothing,Fur,bedding,etc.,sterilizationofbonemeal,fumigationofwarehouses,factories,culturalrelics,books).

Liquidcarbondioxideisusedasarefrigerant,low-temperaturetestsofaircraft,missilesandelectroniccomponents,toimproveoilwellrecovery,rubberpolishingandchemicalreactioncontrol,andcanalsobeusedasafireextinguishingagent.

Supercriticalcarbondioxidecanbeusedasasolventtodissolvenon-polar,non-ionic,andlow-molecular-weightcompounds,soitiswidelyusedinhomogeneousreactions.

Calculationofchemicaldata

Calculationreferencevalueofhydrophobicparameter(XlogP)	0.9
Numberofhydrogenbondacceptors	2
Topologicalmolecularpolarsurfacearea	34.1
Numberofheavyatoms	3
Complexity	18.3
Numberofcovalentbondunits	1

(Tablereference:)

Safetymeasures

Naturalenvironmentaspects

Environmentalhazards

Naturalgreenhouseeffect:greenhousegasessuchascarbondioxideintheatmospherecanstronglyabsorblong-waveradiationfromtheground.Long-waveradiationwithalongerwavelengthisradiatedtotheground,whichplaysaroleininsulatingtheground.

Enhancedgreenhouseeffect:SincetheIndustrialRevolution,humanactivitieshaveemittedalargeamountofgreenhousegasessuchascarbondioxide,whichhascausedtheconcentrationofgreenhousegasesintheatmospheretorisesharply,resultinginanincreasinggreenhouseeffect.Accordingtostatistics,beforeindustrialization,theglobalaverageannualatmosphericcarbondioxideconcentrationwas278ppm(1ppmisonepartpermillion).In2012,theglobalaverageannualatmosphericcarbondioxideconcentrationwas393.1ppm.ByApril2014,themonthlyaveragecarbondioxideconcentrationintheatmosphereofthenorthernhemisphereItexceeded400ppmforthefirsttime.

Globalwarming:Theincreasinggreenhouseeffectoftheatmospherehasledtoglobalwarming,resultinginaseriesofglobalclimateproblemsthatareunpredictablebysciencetoday.AccordingtotheInternationalEconomicsofClimateChangeReport,ifhumanbeingscontinuetomaintaintheircurrentlifestyles,by2100,thereisa50%chancethattheglobalaveragetemperaturewillriseby4°C.Iftheglobaltemperaturerisesby4℃,theglaciersinthenorthandsouthpolesoftheearthwillmelt,andthesealevelwillriseasaresult.Morethan40islandcountriesandthemostpopulouscoastalcitiesintheworldwillbeindangerofbeingsubmerged,withtensofmillionsofpeopleworldwide.Hislifewillfaceacrisis,andevenaglobalecologicalbalancedisorderwilleventuallyleadtolarge-scalemigrationandconflictsaroundtheworld.

Countermeasures

Low-carbonlife:MinimizetheconsumptionindailylifeEnergyneeds,therebyreducingcarbondioxideemissions,reducingairpollution,andslowingdownecologicaldegradation.

CCStechnology:carbondioxidecaptureandstorage(CarbonDioxideCaptureandStorage,abbreviation:CCS)technology,isoneofthemostimportanttechnologiestodealwithglobalclimatechangeintheshortterm,referringtotheuseofcarboncapturetechnology,Separatethecarbondioxideproducedbyindustryandrelatedenergyindustries,andthentransportandsealittotheseabedorunderground,etc.,whichisisolatedfromtheatmosphere,throughstoragemeans.

Internationallaw:AttheUnitedNationsConferenceonEnvironmentandDevelopmentheldinBrazilinJune1992,153countriessignedtheUnitedNationsFrameworkConventiononClimateChange.ThisconventionhasbeeneffectivesinceMarch1994.Thereare176contractingparties(asofFebruary2015);InDecember1997,ameetingattendedbyparticipatingcountriesofthe"JointFrameworkConventiononClimateChange"washeldinKyoto,Japan.Themeetingformulatedthe"KyotoProtocol"asthe"JointFrameworkConventiononClimateChange".AsupplementaryclausetotheFrameworkConventiononChange.ThistreatyhasbeeneffectivesinceFebruary16,2005,andhas183contractingparties(asofFebruary2009);November30-December11,2015,heldinParisAtthe21stConferenceofthePartiestothe"JointFrameworkConventiononClimateChange"andthe11thConferenceofthePartiestothe"KyotoProtocol",representativesfrom195countriesunanimouslyadoptedthe"ParisAgreementoftheUnitedNationsFrameworkConventiononClimateChange"("ParisAgreement").

Intermsofhumanhealth

Researchshowsthatwhentheconcentrationofcarbondioxideintheairislessthan2%,thereisnoobviousharmtohumans.Iftheconcentrationexceedsthisconcentration,itcancausedamagetothehumanrespiratoryorgans.Undercircumstances,carbondioxideisnotatoxicsubstance,butwhentheconcentrationofcarbondioxideintheairexceedsacertainlimit,thebodywillbepoisoned,andhighconcentrationsofcarbondioxidewillsuffocatepeople.Animalexperimentshaveprovedthat:intheairwithnormaloxygencontent(20%),thehighertheconcentrationofcarbondioxide,thehigherthemortalityofanimals.Atthesametime,purecarbondioxidecausesanimaldeathsanddeathscausedbyloweroxygenaremorerapid.Inaddition,somepeoplebelievethatinthecaseoflowoxygen,carbondioxideataconcentrationof8%to10%cancausedeathsofhumansandanimalsinashortperiodoftime.

Principleofpoisoning

High-concentrationcarbondioxideitselfhasstimulatingandanestheticeffectsandcancausehypoxiaandasphyxiationinthebody.

Symptomsofpoisoning

Mild:Generaldiscomfortsuchasdizziness,headache,muscleweakness,andbodyaches.

Moderate:dizzinessmayfalltotheground;chesttightness,unbearablepaininthenasalcavityandthroat,shortnessofbreath,pressureandsuffocationinthechest;severeheadache,tinnitus,muscleweakness,redskin,Bloodpressurerises,pulseisfastandstrong.

Severe:Suddenlydizzyandunabletosupport,falltotheground,holdbreath,dyspnea,palpitations,unconsciousness,coma,bruisingskin,lipsandnails,dropinbloodpressure,weakpulsetoreach,anddilatedpupils.Thelightreflexdisappears,thewholebodyissoft,theglottisisenlarged,andthebreathingandheartbeatstoponeafteranotheruntildeath.Somesymptomssuchaslethargyandmemorylossmayremainaftertheacuteperiod.

Firstaidmeasures

①Quicklygetthepoisonedpersonoutofthehigh-concentrationcarbondioxideenvironment,gotothefreshair,loosenthepoisonedperson’scollar,artificialassistanceBreatheinordertobreatheinoxygenassoonaspossible,andtreatwithhyperbaricoxygenifnecessary.Rescuersshouldweareffectiverespiratoryprotectiveequipment.

②Injectrespiratorystimulants,andantibioticsforsecondaryinfections;intravenousinfusionofsodiumbicarbonateorsodiumlactateforreducedcarbondioxidebindingcapacity;largerdosesofsedativesforlimbspasm;long-termhighfeverandconvulsionsSedativedrugscanbeused;othersymptomatictreatmentssuchaspulmonaryedemaandcerebraledema.

Precautions

Beforeenteringaworkareawithahigherconcentrationofcarbondioxide,checkwhethertheconcentrationofcarbondioxideintheairexceeds2%.Ifitexceeds,youneedtoTakeeffectivesafetymeasures,suchas:①Ventilationanddetoxification,replacingtheairintheworkplace,sothattheconcentrationofcarbondioxideintheairdoesnotexceed2%;②Wearingventilationmasks,self-primingductgasmasks,oxygenbreathingapparatusandothercommonlyusedanti-virusmask.

Storageprecautions

Carbondioxideissuitableforstorageinacool,ventilatednon-combustiblegaswarehouse,suitableforshipmentinliquidorsolidform.Payattentiontothefollowingpointswhenstoringandtransportingcarbondioxide:①Keepawayfromfireandheatsources,andthestoragetemperatureshouldnotexceed30℃;②Storeseparatelyfromeasily(combustible)materialsandavoidmixedstorage;③Thestorageareashouldbeequippedwithleakageemergencytreatmentequipment.

Relevantlawsandregulations

InChina,carbondioxideisreleasedonApril12,2007andimplementedonNovember1,2007.Part1:OccupationalExposureLimitsforHazardousFactorsintheWorkplace:Forthe90thsubstancein"ChemicalHarmfulFactors"(GBZ2.1-2007),intermsofhygienerequirements,thepermissibleconcentration-timeweightedaverage(PC-TWA)intheworkplaceis9000mg/m³,Permissibleconcentration-ShortTermExposureLimit(PC-STEL)is18000mg/m³.Inaddition,thenationalregulationcloselyrelatedtocarbondioxideisthenationalstandard"Methodforthedeterminationofcarbondioxideintheairinpublicplaces"(GB/T18204.24-2000),whichstipulatesthemethodformeasuringtheconcentrationofcarbondioxideintheairinpublicplaces.ThisstandardhasbeenapprovedinSeptember2014.Replacedby"PublicPlaceHygieneInspectionMethodsPart2:ChemicalPollutants"(GB/T18204.2-2014)issuedonDecember3,2014andimplementedonDecember1,2014.Forthedetectionofcarbondioxide,thestandarddetectionmethodsrecommendedby"PublicPlaceSanitationInspectionMethodsPart2:ChemicalPollutants"include3detectionmethods,namely,non-spectralinfraredgasanalysis(theminimumdetectionconcentrationis0.01%),andgaschromatographyMethod(thelowestdetectableconcentrationis0.014%),volumetrictitrationmethod(thelowestdetectableconcentrationis0.001%).

IntheUnitedStates,theAmericanConferenceOFGovernmentalIndustrialHygienists(ACGIH)thresholdconcentration,theOccupationalSafetyandHealthAdministration(OccupationalSafetyandHealthAdministration,OSHA)allowableconcentrationvaluesandTherecommendedconcentrationvalueoftheNationalInstituteforOccupationalSafetyandHealth(NIOSH)is5000ppm(5000×10^-6).