diossido di carbonio

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(therecognizedvalues​​ofthetwoin2013were7.375MPaand303.05K,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.

Reactionwithsodiumhydroxide

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:

;

section>;

.

  • 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).

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)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.

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)allowableconcentrationvalues​​andTherecommendedconcentrationvalueoftheNationalInstituteforOccupationalSafetyandHealth(NIOSH)is5000ppm(5000×10-6).

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