文档名：烷基硅烷化Silicalite1分子筛膜的醇水分离性能
摘要：Silicalite-1分子筛膜因其疏水特性在低浓度有机物/水分离中得到广泛应用.但膜面硅羟基(Si—OH)的存在会严重影响其分离效果.以Silicalite-1分子筛膜为基膜,表面接枝正辛基三乙氧基硅烷(OTES)来消除Si—OH,进一步改善疏水性,提高其分离能力.系统考察OTES浓度、反应温度和修饰时间对于膜改性效果的影响,分析改性机理,并对比改性前后Silicalite-1分子筛膜的渗透汽化稳定性.结果表明,烷基硅烷的接枝能有效提高膜疏水性、分离性能与长期稳定性.当OTES的质量分数为3%、温度为60℃、时间为10h时,所制备的膜在70℃分离3.5%±0.1%(质量分数)的乙醇水溶液,膜通量为0.92kg·m-2·h-1,分离因子达到30.4,且能够在连续120h的渗透汽化过程中,保持良好的稳定性.烷基硅烷接枝优化了Silicalite-1分子筛膜的表面结构,在渗透汽化法回收有机组分领域具有广阔的应用前景.
Abstract：IntroductionSilicalite-1zeolitemembranehasahighseparationperformanceduetoitshydrophobicproperties,whichcanpreferentiallypermeateorganicmoleculesandeffectivelyblockwatermoleculesinaqueous-organicphasemixtures.However,thehydrophilicSi—OHonthesurfaceofSilicalite-1zeolitemembraneisoneofthemostimportantreasonsforthelowhydrophobicityandselectivityofmembrane,whichpreferentiallyadsorbswatermolecules,andeasilyreactswithethanolinthesolutionandgeneratesSi—OC2H5toblockthezeolitepores.Tosolvetheproblemsabove,then-octyltriethoxysilane(OTES)wasgraftedontothesurfaceofSilicalite-1zeolitemembranetoeliminateSi—OH,furtherimprovinghydrophobicityandseparationabilityofthemembrane.TheeffectsofmassfractionofOTES,reactiontemperatureandmodificationtimeonthemembranemodificationwereinvestigated.Themodificationmechanismwasanalyzed,andthepervaporationstabilityofSilicalite-1zeolitemembranebeforeandaftermodificationwascompared.MethodsAmolarratioofprecursorsolutionwasn(TEOS):n(TPAOH):n(H2O):n(NaOH)of1.00:0.05:75.00:0.03.Silicalite-1zeolitewithaparticlesizeof400nmwasusedasseedstoprepareSilicalite-1zeolitemembranesbyasecondarygrowthmethod.Themembraneswerehydrothermallycrystallizedat175℃for8h.Afterwashing,themembraneswerecalcinedat550℃for4htoremovethetemplate,obtainingsilicalite-1zeolitemembranes.Silicalite-1zeolitemembraneswereplacedinasolutionwithOTESasasoluteandtolueneasasolventatdifferentmassfractionsof1%-5%,andmodifiedat20-100℃for5-20h.Themembraneswerewashedwithanhydrousethanoltoremovetheresidualsolvent,andfinallydriedat80℃for12htoobtaintheOTES@Silicalite-1zeolitemembranes.TheseparationperformanceofOTES@Silicalite-1zeolitemembraneswastestedbyalaboratoryhomemadepervaporationdevice.Themembranefluxwascalculatedviaaweighingmethod,theseparationfactorwasanalyzedwiththesolutioncompositiondataonthefeed-sideandpermeate-side.ThephysicalphasecompositionofthemembraneswasdeterminedbyX-raydiffractometry.ThechemicalbondsandfunctionalgroupsofthemembraneswereanalyzedbyFouriertransforminfraredspectroscopy.Themicroscopicmorphologyandelementaldistributionofthemembranesweredeterminedbyscanningelectronmicroscopy.Thehydrophobicityofthemembraneswasanalyzedviawatercontactanglemeasurement.ResultsanddiscussionsTheseparationfactorofOTES@Silicalite-1zeolitemembranesshowsanupwardtrendwiththeincreaseofthemassfractionofOTES.ApartoftheSi—OHonthemembranesurfacearereplacedbyOTES,andthemembranesurfacebecomesmorehydrophobic,whichfavorstheadsorptionanddiffusionofethanolmolecules.AttheOTESmassfractionof3%,theOTES@Silicalite-1zeolitemembranehasthemaximumseparationfactor.However,theseparationfactordecreasesasthemassfractionofOTESfurtherincreases.ThisispossiblyduetotheexcessOTEScoveringtheporesonthemembranesurfaceandaffectingthetransportationofethanol.AsSi—OHeliminates,theamountofSi—OC2H5decreases,sothemembranefluxtrendaupwardinitially.However,thehydrophobicityofOTEShindersthewatermoleculetransportation,thusreducingthemembraneflux.Asthetemperatureincreases,thegraftingreactioniseasiertoaccomplish,andthehydrophobicityoftheOTES@Silicalite-1zeolitemembraneenhances.At60℃,themembraneshowsthemaximumseparationfactorandmembraneflux.However,theseparationperformanceofthemembranedecreasesslightlyasthetemperaturefurtherincreases,whichisattributedtotheexcessiveandpromiscuousorganicgroupsthatblockethanolpermeation,whilereducingwaterflux.Thehydrophobicityandselectivityofthemembraneimproveat5-10hasthemodificationtimeincreases.At10h,themembranehasthemaximumseparationfactor.However,theseparationperformanceofthemembranedecreasessharplyasthemodificationtimefurtherincreasespossiblyduetotheOTEScross-linkwitheachothertoformpolymers,whichseverelyblocktheporesofthezeolite,resultinginasignificantdecreaseinmembraneflux.Also,thetransportofethanolisimpeded,thusdecreasingtheseparationfactor.ConclusionsThesurfacemodificationofOTEScouldnotdamagetheframeworkandcrystalstructureofSilicalite-1zeolitemembrane.ItcouldeffectivelyeliminatetheSi—OHonthemembranesurface,improvethehydrophobicityandseparationperformanceofthemembrane.TheSilicalite-1zeolitemembraneshowedthemembranefluxof0.92kg·m-2·h-1andtheseparationfactorof30.4at70℃for3.5%±0.1%ethanolaqueoussolution,whichwasmodifiedatamassfractionofOTESof3%and60℃for10h.Meanwhile,thismembranecouldalsomaintainagreatstabilityduringthepervaporationtestfor120h.ThisstudyindicatedthatalkylsilanegraftingcouldbeaneffectivemeasuretosubstantiallyimprovethehydrophobicityandseparationperformanceofSilicalite-1zeolitemembrane,havingpromisingapplicationprospectsinthefieldoforganiccomponentrecoverybypervaporation.
作者：赵业昊 吴红丹 周志辉 赵尧Author：ZHAOYehao WUHongdan ZHOUZhihui ZHAOYao
作者单位：武汉科技大学资源与环境工程学院,冶金矿产资源高效利用与造块湖北省重点实验室,武汉430081
刊名：硅酸盐学报 ISTICEIPKU
Journal：JournaloftheChineseCeramicSociety
年，卷(期)：2024, 52(7)
分类号：TQ028
关键词：Silicalite-1分子筛膜 烷基硅烷 接枝改性 醇水分离 渗透汽化
Keywords：Silicalite-1zeolitemembrane alkylsilane graftmodification ethanolaqueoussolutionseparation pervaporation
机标分类号：TQ028.8O631TB383
在线出版日期：2024年7月24日
基金项目：湖北省教育厅科学研究计划指导性项目烷基硅烷化Silicalite-1分子筛膜的醇水分离性能[
期刊论文] 硅酸盐学报--2024, 52(7)赵业昊 吴红丹 周志辉 赵尧Silicalite-1分子筛膜因其疏水特性在低浓度有机物/水分离中得到广泛应用.但膜面硅羟基(Si—OH)的存在会严重影响其分离效果.以Silicalite-1分子筛膜为基膜,表面接枝正辛基三乙氧基硅烷(OTES)来消除Si—OH,进一步改善疏...参考文献和引证文献
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