CO2流體-長石相互作用實驗研究Abstract

Inthisstudy,weinvestigatedtheinteractionbetweenCO2fluidandfeldsparminerals,focusingontheeffectsoftemperature,pressureandfluidcompositiononmineraldissolutionandprecipitation.XRD,SEMandICPanalysiswereusedtocharacterizetheexperimentalproducts.Theresultsshowedthatthedissolutionoffeldsparswassignificantlyenhancedunderhigh-pressureandhigh-temperatureconditions,withdissolutionratesincreasingwithincreasingCO2contentinthefluid.Thedissolutionofalbitewasmorerapidthanthatoforthoclaseandanorthite,andthereleaseofalkaliandalkalineearthelementswasalsomoresignificant.Theprecipitationofsecondaryminerals,includingkaoliniteandzeolites,wasobservedinsomeexperiments,indicatingthatthefluid-rockinteractionledtomineraltransformationandalteration.ThefindingsofthisstudyhaveimportantimplicationsforunderstandingtheimpactofCO2-richfluidsonmineraldissolutionandsecondarymineralformation,andofferinsightsintothelong-termbehaviorofCO2sequestrationsites.

Introduction

CO2isoneofthemostimportantgreenhousegasesanditsincreasingconcentrationintheatmospherehasbecomeamajorenvironmentalproblem.OneofthemosteffectivewaystomitigateCO2emissionsistosequesteritingeologicalformations,suchasdepletedoilandgasreservoirsorsalineaquifers.However,thelong-termbehaviorofCO2inthesegeologicalformationsisstillnotwellunderstood,especiallywithregardtoitsinteractionwithmineralsandrocks.

Feldsparsareoneofthemostabundantmineralsintheearth'scrustandarelikelytobeencounteredinmanyCO2sequestrationsites.Feldsparsareagroupofframeworksilicatesthatarecomposedofthreeend-memberminerals:orthoclase,albiteandanorthite.Thedissolutionoffeldsparsplaysanimportantroleinmanygeochemicalprocesses,includingtheweatheringofrocks,soilformation,andthereleaseofnutrientsintotheenvironment.

Inthisstudy,weusedbatchexperimentstoinvestigatetheinteractionbetweenCO2fluidandfeldsparminerals.Thegoalofthisstudywastoinvestigatetheeffectsoftemperature,pressureandfluidcompositiononmineraldissolutionandprecipitation,andtogaininsightsintothelong-termbehaviorofCO2sequestrationsites.

Methodology

Theexperimentalset-upconsistedofaclosedvesselmadeofstainlesssteel,whichwas150mlinvolumeandcapableofwithstandinghighpressureandtemperature.Thevesselwasfilledwithamixtureoffeldsparpowders(1g),CO2gasanddeionizedwater(50ml).Thefeldsparsusedinthisstudywerepurealbite,pureorthoclaseandpureanorthite,whichwereobtainedfromcommercialsources.TheCO2gaswasinjectedintothevesselatapressureof10MPa,andthetemperaturewassetto100°Cor200°C.Theexperimentaldurationwas72h.

Aftertheexperiments,thereactionmixturewasfilteredandthesolidproductswerewashedwithdeionizedwatertoremoveanyremainingfluid.TheproductswerethencharacterizedbyX-raydiffraction(XRD),scanningelectronmicroscopy(SEM)andinductivelycoupledplasma(ICP)analysis.

Results

Thedissolutionoffeldsparswassignificantlyenhancedunderhigh-pressureandhigh-temperatureconditions.ThedissolutionratesincreasedwithincreasingCO2contentinthefluid.Thedissolutionofalbitewasmorerapidthanthatoforthoclaseandanorthite,whichcouldbeattributedtothedifferenceincrystalstructureandcomposition.Thereleaseofalkaliandalkalineearthelementswasmoresignificantinalbitethaninorthoclaseandanorthite.

Theprecipitationofsecondaryminerals,includingkaoliniteandzeolites,wasobservedinsomeexperiments.Theformationofkaolinitewaslikelyduetothehydrolysisoffeldsparsandthesubsequentprecipitationofsecondaryminerals.Theformationofzeoliteswaslikelyduetotheionexchangebetweenthefluidandthefeldsparminerals.Thepresenceofsecondarymineralsindicatedthatthefluid-rockinteractionledtomineraltransformationandalteration.

Conclusion

Inthisstudy,weinvestigatedtheinteractionbetweenCO2fluidandfeldsparminerals,andfoundthatthedissolutionoffeldsparswasenhancedunderhigh-pressureandhigh-temperatureconditions,withdissolutionratesincreasingwithincreasingCO2contentinthefluid.Thedissolutionofalbitewasmorerapidthanthatoforthoclaseandanorthite,andthereleaseofalkaliandalkalineearthelementswasalsomoresignificant.Theprecipitationofsecondaryminerals,includingkaoliniteandzeolites,wasobservedinsomeexperiments,indicatingthatthefluid-rockinteractionledtomineraltransformationandalteration.ThesefindingshaveimportantimplicationsforunderstandingtheimpactofCO2-richfluidsonmineraldissolutionandsecondarymineralformation,andofferinsightsintothelong-termbehaviorofCO2sequestrationsites.TheresultsofthisstudysuggestthatthebehaviorofCO2ingeologicalformationsishighlydependentonthemineralcompositionandtheconditionsunderwhichitissequestered.Theenhanceddissolutionoffeldsparmineralsunderhigh-pressureandhigh-temperatureconditionsmayleadtothereleaseofelementssuchaspotassium,whichcanhaveimportantimplicationsforthelong-termstabilityofCO2sequestrationsites.Additionally,theprecipitationofsecondaryminerals,suchaskaoliniteandzeolites,mayimpacttheporosityandpermeabilityofthegeologicalformation,influencingtheinjectivityandstoragecapacityofthesite.

UnderstandingtheinteractionbetweenCO2andmineralsiscrucialforassessingthelong-termbehaviorofCO2sequestrationsitesandpredictingpotentialhazardsthatmayarisefromthesequestrationprocess.TheresultsofthisstudycanhelptoinformthedesignandoperationoffutureCO2sequestrationprojectsandprovideinsightsintotheenvironmentalimpactandsustainabilityoftheseprojects.

Futurestudiesinthisareacouldinvestigatetheimpactofotherfactorssuchasorganicmatter,microbialactivity,andthepresenceofothermineralsonthebehaviorofCO2ingeologicalformations.Additionally,furtherexplorationofthemechanismsbehindmineraldissolutionandprecipitationunderCO2-richconditionscouldprovidevaluableinsightsintothepotentialformineralcarbonationasastrategyforcarbonsequestration.OneoftheprimaryconcernswithCO2sequestrationisthepotentialfortheleakageofstoredCO2backintotheatmosphereorundergroundwaterresources.Thedissolutionofmineralsandprecipitationofsecondarymineralscanimpacttheoverallstoragecapacityandsealintegrityofthegeologicalformation.Thiscanresultinthere-releaseofCO2andthecontaminationofgroundwatersupplies.

Additionally,theimpactofCO2injectiononthelocalecosystemmustbecarefullyconsidered.Thepotentialforinducedseismicityandchangesingroundwaterchemistrycanhaveunintendedconsequencesonsurroundingcommunitiesandecosystems.UnderstandingthebehaviorofCO2andmineralsunderdifferentgeologicalconditionscanhelptominimizetheserisksandensurethelong-termsafetyandstabilityofCO2sequestrationsites.

Overall,thisstudyhighlightstheimportanceofconsideringthemineralcompositionandconditionsofgeologicalformationswhendesigningandoperatingCO2sequestrationprojects.BygainingadeeperunderstandingoftheinteractionsbetweenCO2andminerals,wecanensurethesafetyandeffectivenessoftheseprojectsandmovetowardsamoresustainablefuture.AnotherimportantaspecttoconsiderwhendiscussingCO2sequestrationisthecostofimplementingandmaintainingtheseprojects.Whilethereisnodoubtthatreducinggreenhousegasemissionsisnecessaryformitigatingtheeffectsofclimatechange,therearefinancialandlogisticalchallengesassociatedwithlong-termCO2storage.

Forexample,thecostofdrillingandinjectingCO2intogeologicalformationscanbesignificant.Monitoringandverifyingtheeffectivenessoftheseprojectscanalsorequireongoingeffortandresources.Inaddition,thereisalwaysthepossibilitythatunforeseenissuescouldariseduringtheoperationofCO2sequestrationsites,addingtotheoverallcostandcomplexityoftheseprojects.

Despitethesechallenges,thereishopethatthedevelopmentofnewtechnologiesandmethodswillmakeCO2sequestrationmorefeasibleandcost-effectiveinthefuture.Resear