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Proučavanje uticaja različitih postupaka modifikacije na fizičko-hemijske karakteristike i sorpciona svojstva sepiolita

dc.contributor.advisorPetrović, Rada
dc.contributor.otherJanaćković, Đorđe
dc.contributor.otherOnjia, Antonije
dc.creatorLazarević, Slavica
dc.date.accessioned2021-03-10T15:10:33Z
dc.date.available2021-03-10T15:10:33Z
dc.date.issued2012
dc.identifier.urihttp://eteze.bg.ac.rs/application/showtheses?thesesId=844
dc.identifier.urihttps://fedorabg.bg.ac.rs/fedora/get/o:7208/bdef:Content/download
dc.identifier.urihttp://vbs.rs/scripts/cobiss?command=DISPLAY&base=70036&RID=44828943
dc.identifier.urihttp://TechnoRep.tmf.bg.ac.rs/handle/123456789/4606
dc.description.abstractThe aim of this study was to investigate the influence of modification of natural sepiolite using: 3-mercaptopropyltrimethoxysilane (HS(CH2)3Si(OCH3)3), [3-(2- aminoethylamino)propyl]trimethoxysilane ((CH3O)3Si(CH2)3NH(CH2)2NH2)), N-[3- (trimethoxysilyl)propyl], ethylenediamine triacetic acid trisodium salt ((CH3O)3Si(CH2)3N(CH2COONa)N(CH2)2N(CH2COONa)2) and iron(III)chloride in basic conditions, on physico-chemical properties, sorption of Cu2+, Co2+ and Ni2+ ions from water solutions and sorption of organic molecules from the gas phase. The point of zero charge, pHtnn, as an important surface parameter, was determined in electrolyte solutions with different initial concentration and in the solution of M2+ ions. The value of pHtnn remains constant with changing concentration of the KNO3 solution. The shift of the point of zero charge of sepiolite samples was determined in the presence of Cu2+, Co2+ and Ni2+ ions indicating that specific sorption of M2+ ions onto sepiolite samples had occurred. The improvement of the sorption efficiency of samples obtained by modification of sepiolite with mercapto-silane and amino-silane was not observed. Modification of natural sepiolite by iron oxyhydroxide resulted in formation of an effective sorbent for sorption of Cu2+, Co2+ and Ni2+ ions, while in the case of modification by ethylenediamine triacetic acid trisodium salt from water solution, the increase of sorption capacity was deteced for sorption of Ni2+ ions. The sorption of Cu2+, Co2+ and Ni2+ ions from water solutions is the result of the process of ion exchange of Mg2+ ions from the sepiolite structure and specific sorption. According to maximal sorption capacities, the sorption was the highest in the case of Cu2+ ions, then Co2+, and the lowest in case of Ni2+ ions, for used all sorbent. The equilibrium sorption process, for all investigated ions, on natural, as well as on modified samples, was well described by the Langmuir isotherm model. The change of the initial pH value, in the pH range where sorbent dissolution and hydrolysis of ions can be excluded, did not affect the change of capacities of sorption, on natural, as well on modified samples. The quantity of sorbed Cu2+, Co2+ and Ni2+ ions increased with increasing temperature. The positive enthalpy change indicates that the process of removal of M2+ ions from water solution by sepiolites was endothermic. The sorption kinetic study showed that pseudo-second order was the model that best described the experimental sorption data for all investigated ions and all the sorbents used, indicating that the sorption may be controlled by chemical sorption. The ionization constants of the surface functional groups of sepiolite modified with iron(III)chloride in basic conditions (Fe-SEP) determined from the potentiometric titration data, were p int a1 K = 6.7 ± 0.1 and p int a2 K = 10.2 ± 0.1. The relative acidity of the surface functional groups was lower comparing to natural sepiolite sample, that can be assigned to the presence of iron oxyhydroxide particles at the surface of modified material. The thermodynamic parameters (free energy, enthalpy, entropy) of adsorption as well as dispersive and specific components of free energy of adsorption were calculated from the inverse gas chromatography measurements for the probes on the sample Fe- SEP in temperature range 483-513K. The results of interactions of Fe-SEP amd bacis, acid and amphoteric organic probes indicate that Fe-SEP surface has basic character. The sorption isotherms for n-hexane, benzene, chloroform and tetrahydrofurane, on sample Fe-SEP, determined by inverse gas chromatography at finite concentration condition in the temperature range 483-513 K, were used to estimate the surface area, isosteric heat of adsorption and adsorption energy distribution function. The strong interaction between Fe-SEP surface and chloroform, due to acid-base interactions, was established.en
dc.description.abstractPredmet ove doktorske disertacije je proučavanje uticaja modifikacije prirodnog sepiolita primenom soli N-[(3-trimetoksi)propil]etilendiamintriacetatne kiseline ((CH3O)3Si(CH2)3N(CH2COONa)N(CH2)2N(CH2COONa)2), [3-(2- aminoetilamino)propil]trimetoksisilana ((CH3O)3Si(CH2)3NH(CH2)2NH2)), 3- merkaptopropiltrimetoksisilana (HS(CH2)3Si(OCH3)3) i gvožñe(III)-hlorida u baznoj sredini na fizičko-hemijska svojstva sepiolita, kao i na sorpciju Cu2+, Co2+ i Ni2+ jona iz vodenih rastvora i sorpciju organskih jedinjenja iz gasovite faze. Karakteristično svojstvo površine, tačka nultog naelektrisanja, pHtnn, odreñena je u rastvoru elektrolita različite koncentracije, kao i u prisustvu jona Cu2+, Co2+ i Ni2+. Utvrñeno je da se tačka nultog naelektrisanja ne menja sa promenom koncentracije rastvora KNO3, dok se u prisustvu Cu2+, Co2+ i Ni2+ jona pomera ka nižim pH vrednostima, što ukazuje na specifčnu sorpciju jona. Postupak modifikacije prirodnog sepiolita merkapto-silanom i amino-silanom nije doveo do povećanja sorpcije jona. Uzorak modifikovan oksidom gvožña pokazao se kao efikasan sorbent u sorpciji Cu2+, Co2+ i Ni2+ jona, dok je u slučaju modifikacije vodenim rastvorom natrijumove soli N-[(3-trimetoksi)propil]etilendiamintriacetatne kiseline uočen porast sorpcionog kapaciteta za Ni2+ jone. Sorpcija jona Cu2+, Co2+ i Ni2+ iz vodenog rastvora rezultat je istovremenog odigravanja procesa jonske izmene sa Mg2+ jonima iz sepiolitske strukture i specifične sorpcije. Poreñenjem maksimalnih sorpcionih kapaciteta utvrñeno je kod svih ispitanih sorbenata najveća sorpcija Cu2+ jona, zatim Co2+ jona a najmanja sorpcija Ni2+ jona. Proces sorpcije ispitanih jona na prirodnom, kao i na modifikovanim sepiolitima najbolje se opisuje Langmuir-ovom izotermom. Promena pH vrednosti, u oblasti u kojoj ne dolazi do rastvaranja sorbenta i hidrolize jona, nije bitno uticala na količinu sorbovanih jona na prirodnom sepiolitu, kao ni na modifikovanim uzorcima. Sorpcija jona Cu2+, Co2+ i Ni2+ jona raste sa porastom temperature. Pozitivne vrednosti promene entalpije sorpcije pokazuju da je sorpcija endoterman proces. Ispitivanje kinetike sorpcije, pri istoj polaznoj koncentraciji jona metala pokazalo je da kinetički model pseudo-drugog reda najbolje opisuje eksperimentalne rezultate, za sve ispitane sorbente. Vrednosti konstanti jonizacije uzorka sepiolita modifikovanog gvožñe(III)- hloridom u baznoj sredini (Fe-SEP) iznose: p 1 int a K = 6,7 ± 0,1 i p 2 int a K = 10,2 ± 0,1. Uzorak ima veću relativnu kiselost površinskih funkcionalnih grupa u odnosu na prirodni sepiolit, usled prisustva gvožñe(III)-oksihidroksida u strukturi modifikovanog sepiolita. Primenom inverzne gasne hromatografije u uslovima nulte prekrivenosti u temperaturnom opsegu 483-513 K izračunate su vrednosti osnovnih termodinamičkih parametara adsorpcije (slobodne površinske energije, standardne entalpije i standardne entropije adsorpcije) na uzorku Fe-SEP, kao i specifična i disperzivna komponenta slobodne energije adsorpcije. Rezultati ispitivanja interakcija uzorka Fe-SEP i kiselih, baznih i amfoternih organskih molekula pokazali su da je površina ispitanog uzorka baznog karaktera. Na osnovu dobijenih adsorpcionih izotermi za n-heksan, benzen, hloroform i tetrahidrofuran na sepiolitu Fe-SEP primenom inverzne gasne hromatografije u uslovima konačne prekrivenosti u temperaturnom opsegu 483-513 K i B.E.T. jednačine izračunate su vrednosti specifične površine, izosterične toplote adsorpcije, kao i raspodela adsorpcione energije. Površina sepiolita pokazuje povećani afinitet prema hloroformu usled uspostavljanja jakih kiselo-baznih interakcija.sr
dc.publisherUniverzitet u Beogradu, Tehnološko-metalurški fakultet
dc.relationinfo:eu-repo/grantAgreement/MESTD/Integrated and Interdisciplinary Research (IIR or III)/45019/RS//
dc.rightsopenAccess
dc.rights.urihttps://creativecommons.org/licenses/by-nc-nd/4.0/
dc.subjectsepioliteen
dc.subjectmodificationen
dc.subjectorganosilanesen
dc.subjectiron oxyhydroxideen
dc.subjectspecific sorptionen
dc.subjection exchangeen
dc.subjectinverse gas chromatographyen
dc.subjectsepiolitsr
dc.subjectmodifikacijasr
dc.subjectorgano-silanisr
dc.subjectoksihidroksidi gvožđasr
dc.subjectspecifična sorpcijasr
dc.subjectjonska izmenasr
dc.subjectjoni metalasr
dc.subjectinverzna gasna hromatografijasr
dc.titleThe influence of modification methods on physico-chemical and sorption properties of sepiolite Umnoženo za odbranu.en
dc.titleProučavanje uticaja različitih postupaka modifikacije na fizičko-hemijske karakteristike i sorpciona svojstva sepiolitasr
dc.typedoctoralThesis
dc.rights.licenseBY-NC-ND
dc.identifier.fulltexthttp://TechnoRep.tmf.bg.ac.rs/bitstream/id/2132/4603.pdf
dc.identifier.rcubhttps://hdl.handle.net/21.15107/rcub_technorep_4606
dc.type.versionpublishedVersion


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