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Title:PRIPRAVA IN KARAKTERIZACIJA SiO2 AEROGELOV MODIFICIRANIH Z ORGANSKIMI FUNKCIONALNIMI SKUPINAMI TER NJIHOVA UPORABA V ADSORPCIJSKIH PROCESIH
Authors:ID Štandeker, Suzana (Author)
ID Novak, Zoran (Mentor) More about this mentor... New window
ID Knez, Željko (Comentor)
Files:.pdf DR_Standeker_Suzana_2010.pdf (5,33 MB)
MD5: DD5ECC61499CAC97C4C60E69B4AFC828
PID: 20.500.12556/dkum/275ee0d1-3e77-4252-b387-39a5b5cec104
 
Language:Slovenian
Work type:Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:Z inkorporacijo metiltrimetoksisilana (MTMS) in trimetiletoksisilana (TMES) v standardno sol-gel sintezo smo pripravili monolitne aerogele SiO2 z različno stopnjo hidrofobnosti. Odlične lastnosti aerogelov, dobljene s sol-gel sintezo, smo ohranili s sušenjem s superkritičnim CO2. Stopnjo hidrofobnosti aerogelov smo določili s pomočjo merjenja kontaktnega kota () med kapljico vode in površino aerogela. Karakterizacijo aerogelov smo izvedli tudi z infrardečo spektroskopijo s Fourier-evo transformacijo (FTIR), diferencialno dinamično kalorimetrijo (DSC) in termogravimetrično analizo (TGA), sorpcijo N2 ter vrstično elektronsko mikroskopijo (SEM). Tako smo opazovali vpliv modifikacije na lastnosti SiO2 aerogelov. Te modificirane aerogele je možno nadalje uporabiti v adsorpcijskih procesih in so dobra alternativa konvencionalnim adsorbentom, kot sta aktivno oglje (AC) in silika gel (SG). Super hidrofobna aerogela smo nadalje uporabili za odstranjevanje različnih toksičnih organskih spojin (toluen, benzen, klorobenzen, etilbenzen, ksilen, kloroform, 1,2-dikloroetan in trikloroetilen) iz vode. Adsorpcijske izoterme smo določili s pomočjo konvencionalne šaržne ekvilibracijske metode. Na podlagi rezultatov meritev adsorpcijske kapacitete lahko trdimo, da so takšni modificirani hidrofobni SiO2 aerogeli odlični adsorbenti in v primerjavi z granuliranim aktivnim ogljem (GAC) izkazujejo kapacitete, ki so 15 do 400-krat večje v primeru vseh testiranih organskih topil. Adsorpcijske lastnosti aerogelov so stabilne tudi po dvajsetih ciklih adsorpcije/desorpcije. Nadalje smo uporabili SiO2 aerogele različne stopnje hidrofobnosti za odstranjevanje in povrnitev hlapov organskih topil (benzen, toluen, etilbenzen in ksilen) iz zraka. Adsorpcijsko kapaciteto različnih aerogelov smo določili z uporabo mini-kolone. Kontinuirane meritve adsorpcije nam kažejo, da so SiO2 aerogeli odlični adsorbenti hlapov BTEX (benzen, toluen, etilbenzen in ksilen) iz zraka. V primerjavi z najbolj uporabljanimi adsorbenti, kot sta AC in SG, aerogeli izkazujejo kapacitete, ki zelo presegajo kapacitete obeh konvencionalnih adsorbentov. Z večanjem stopnje hidrofobnosti aerogeli postanejo manj učinkoviti, vendar je njihova prednost ta, da ne vežejo zračne vlage iz zraka. Izvedli smo tudi modifikacijo površine SiO2 aerogelov z amino (-NH2) ali merkapto (-SH) funkcionalnimi skupinami. V običajni sol-gel sintezi smo uporabili različne ko-prekurzorje, ki v svoji strukturi vsebujejo želeno funkcionalno skupino. Alkogele smo posušili z ekstrakcijo topila s superkritičnim (SC) CO2. Modificirane aerogele smo analizirali z uporabo FTIR-a, DSC/TGA-ja, sorpcijo N2 ter SEM-a ter tako preverili učinkovitost modifikacije ter vpliv le-te na lastnosti aerogelov. Za merkapto modificirane aerogele smo ugotovili, da so dobri adsorbenti Cu(II) in Hg(II) ionov iz vode. Sposobnost odstranjevanja Cu(II) in Hg(II) ionov iz vode teh aerogelov smo določili s šaržnimi adsorpcijskimi testi pri ravnotežnih pogojih. Aerogelni adsorbent z merkapto funkcionalnimi skupinami izkazuje velik adsorpcijski potencial za ione obeh težkih kovin in 99% učinkovitost adsorpcije je bila dosežena v pH območju med 4 in 6. Ravnotežne eksperimentalne podatke smo korelirali s Freundlich-ovim in Langmuir-jevim modelom adsorpcijskih izoterm ter jih primerjali z drugimi adsorbenti, ki se uporabljajo v te namene; ugotovili smo, da so naši adsorbenti zelo učinkoviti.
Keywords:sol-gel sinteza, aerogeli, sušenje s SC CO2, hidrofobnost, organska modifikacija, adsorpcija, VOCs (volatile organic compounds), BTEX, Cu(II) ioni, Hg(II) ioni
Place of publishing:Maribor
Publisher:[S. Štandeker]
Year of publishing:2010
PID:20.500.12556/DKUM-16671 New window
UDC:544.744.2(043.3)
COBISS.SI-ID:253268992 New window
NUK URN:URN:SI:UM:DK:6483PDUR
Publication date in DKUM:08.11.2010
Views:4386
Downloads:395
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
:
ŠTANDEKER, Suzana, 2010, PRIPRAVA IN KARAKTERIZACIJA SiO2 AEROGELOV MODIFICIRANIH Z ORGANSKIMI FUNKCIONALNIMI SKUPINAMI TER NJIHOVA UPORABA V ADSORPCIJSKIH PROCESIH [online]. Doctoral dissertation. Maribor : S. Štandeker. [Accessed 21 March 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=16671
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Secondary language

Language:English
Title:PREPARATION AND CHARACTERIZATION OF SILICA AEROGELS MODIFIED WITH ORGANIC FUNCTIONAL GROUPS AND THEIR USE IN ADSORPTION PROCESSES
Abstract:Silica monolith aerogels with different degrees of hydrophobicity were prepared by incorporating methyltrimethoxysilane (MTMS) or trimethylethoxysilane (TMES) in standard sol-gel synthesis. Excellent properties of aerogels, obtained with the sol-gel synthesis, were preserved with supercritical drying with CO2. The degree of hydrophobicity of the aerogels was tested by measuring the contact angle () of a water droplet with the aerogel surface. The aerogels were characterised by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetry (TGA) measurements, nitrogen physisorption and scanning electron microscope (SEM). The influence of aerogel chemical modification on their properties was also studied. Those modified silica aerogels can be used in adsorption processes and they are good alternative to the conventional adsorbents as activated carbon (AC) and silica gel (SG). Super hydrophobic silica aerogels were used for removal of different toxic organic compounds (toluene, benzene, chlorobenzene, ethylbenzene, xylene, chloroform, 1,2-dichloroethane, trichloroethylene) from water. Adsorption isotherms were measured by conventional batch equilibration procedure. Adsorption capacity measurements show that such modified hydrophobic silica aerogels are excellent adsorbents and compared to granulated active carbon (GAC) exhibit capacities which are from 15 to 400 times higher for all tested compounds. Adsorption properties of hydrophobic silica aerogel remain stable even after 20 adsorption/desorption cycles. Silica aerogels of different degree of hydrophobicity were also used for the removal and the recovery of organic vapours (benzene, toluene, ethylbenzene, xylene) from gas streams. The adsorption capacity measurements of different silica aerogels were done by mini-column method. Continuous adsorption measurements show that silica aerogels are excellent adsorbents of BTEX (benzene, toluene, ethylbenzene and xylene) vapours from waste gas stream. Compared to the most used adsorbents, such as AC and SG, aerogels exhibit capacities which enormously exceed that of both commonly used adsorbents. By increasing the degree of hydrophobicity, aerogels become less effective, but they do not adsorb water vapour from gas stream. Surface modified silica aerogels with amino (-NH2) or mercapto (-SH) functional group were also synthesized by standard sol-gel synthesis with incorporation of different co-precursors, containing in their structure desired functional group. Alcogels were dried by supercritical (SC) CO2. The modified aerogels were characterized by FTIR, DSC/TGA, nitrogen sorption and SEM measurements and by this the efficacy of the modification and influence on aerogel properties was observed. It was found for mercapto aerogels that they are excellent adsorbents of copper and mercury ions from water. The ability of modified silica aerogel with mercapto group to remove Cu(II) and Hg(II) from aqueous solutions was assessed using batch adsorption technique under equilibrium conditions. Aerogel adsorbent with mercapto functional groups exhibits very high adsorption potential for both heavy metals ions and more than 99.0 % removal was achieved in the pH range between 4 and 6. The measured equilibrium data for adsorption isotherms were fitted well by the Freundlich and Langmuir isotherm model and comparing to other used adsorbents for this application prepared aerogels exhibit very high adsorption capacities.
Keywords:sol-gel synthesis, aerogels, SC CO2 drying, hydrophobicity, organic modification, adsorption, VOCs (volatile organic compounds), BTEX, Cu(II) ions, Hg(II) ions


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