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Title:Advancement of carbon nanomembranes for filtration of aqueous solutions : doctoral dissertation
Authors:ID Ambrož, Ana (Author)
ID Petrinić, Irena (Mentor) More about this mentor... New window
ID Gölzhäuser, Armin (Comentor)
Files:.pdf DOK_Ambroz_Ana_2026.pdf (6,14 MB)
MD5: D3FD1F8CCE464645C29FECFF8FB0DCEF
 
Language:English
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:Membrane-based separation technologies play a critical role in water treatment, yet they remain constrained by fundamental trade-offs between permeability and selectivity, as well as performance losses during prolonged operation. To address these limitations, this dissertation investigates the potential of carbon nanomembranes (CNMs), ultrathin, two-dimensional carbon sheets with nanometer-scale thickness, as selective barriers with high water flux and controlled solute rejection. Two types of CNM-composite membranes are fabricated and examined: (i) transferred CNMs, where CNM layer is first fabricated on the initial substrate and then transferred onto ceramic or track-etched polyethylene terephthalate (TE-PET) supports, and (ii) transfer-free CNMs, where the selective CNM layer is directly fabricated on ion-irradiated PET, avoiding transfer-related defects and scalability limitations. The fabricated membranes are characterized for their surface morphology, stability, and filtration performance. Transferred CNMs reveal major adhesion challenges, particularly on rough ceramic supports, leading to delamination and ruptures that compromise membrane integrity. TE-PET provides a more compatible surface due to its smoother topography, yet stability during forward osmosis (FO) filtration remains problematic. Transfer-free CNMs, by contrast, exhibit better structural robustness and scalability, enabling systematic testing in both FO and low-pressure reverse osmosis (LPRO). Performance evaluation highlights the potential of CNMs as high-efficiency membranes. In FO, transfer-free CNM with low defect densities achieves water fluxes of 28 L/m2h, nearly double those of a commercial FO membrane, while maintaining minimal solute reverse flux (0.02 g/L). In LPRO, CNMs demonstrate stable nanofiltration-like rejection of ~50% of NaCl across multiple filtration cycles, comparable to commercial benchmarks. These findings confirm that molecularly thin CNMs can be tailored for high permeability and selectivity, addressing key limitations of conventional membranes. However, challenges remain with TE-PET supports. A gradual water flux decline is observed during extended aqueous filtration, primarily due to polymer swelling within pore walls. To mitigate swelling, surface functionalization with trimethylchlorosilane is explored, reducing hydrophilicity and improving flux stability. By demonstrating that ultrathin CNMs can achieve water permeabilities and selectivities comparable to or exceeding state-of-the-art membranes, while diagnosing and addressing critical fabrication and support-related challenges, this work advances CNMs one step closer toward practical application. With further optimization of support materials, fabrication methods, and surface modifications, CNM-composite membranes hold strong potential as next-generation solutions for water treatment and related separation technologies.
Keywords:Carbon nanomembrane, track-etched support, polyethylene terephthalate, swelling, forward osmosis, reverse osmosis.
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[A. Ambrož]
Year of publishing:2025
Number of pages:XIII, 101 str.
PID:20.500.12556/DKUM-94033 New window
UDC:544.725(043.3)
COBISS.SI-ID:266914307 New window
Publication date in DKUM:29.01.2026
Views:184
Downloads:23
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:29.07.2025

Secondary language

Language:Slovenian
Title:Razvoj ogljikovih nanomembran za filtracijo vodnih raztopin
Abstract:Membranske tehnologije imajo ključno vlogo pri čiščenju vode, vendar jih še vedno omejujejo temeljni kompromisi med prepustnostjo in selektivnostjo membrane ter izgubo njene zmogljivosti med daljšim delovanjem. Za preseganje teh omejitev delo proučuje potencial ogljikovih nanomembran (ang. carbon nanomembranes, CNMs), izjemno tankih dvodimenzionalnih ogljikovih plasti, ki služijo kot selektivne pregrade z visoko prepustnostjo za vodo in nadzorovanim zadrževanjem topljencev. Izdelani in raziskani sta dve vrsti CNM kompozitnih membran: (i) prenesene (ang. transferred) CNM, pri katerih je CNM plast najprej izdelana na začetnem substratu, nato pa je prenesena na keramično ali ciljno jedkano (ang. track-etched, TE) polietilen tereftalatno (PET) podporno plast ter (ii) CNM kompozitne membrane brez prenosa (ang. transfer-free CNMs), kjer je selektivna plast neposredno sintetizirana na ionsko obsevan PET, s čimer se izognemo poškodbam, povezanih s prenosom ter velikostnim omejitvam izdelanih membran. CNM kompozitne membrane so analizirane glede na površinsko morfologijo, stabilnost in filtracijske lastnosti. Pri prenesenih CNM kompozitnih membranah so se pokazale težave z adhezijo, zlasti na grobih keramičnih podpornih plasteh, kar vodi do odstopanja selektivne plasti in poškodb, ki ogrozijo celovitost membrane. TE-PET se je izkazal kot primernejši nosilec zaradi gladkejše površine, vendar je stabilnost med filtracijo s procesom osmoze (ang. forward osmosis, FO) ostala problematična. Nasprotno, pa so se CNM kompozitne membrane brez prenosa izkazale za strukturno robustnejše, kar je omogočilo sistematično testiranje tako v FO procesu kot tudi v nizkotlačnem reverzno osmoznem procesu (ang. low-pressure reverse osmosis, LPRO). Rezultati testiranj potrjujejo potencial CNM kot visoko zmogljivih membran. V FO procesu so CNM kompozitne membrane brez prenosa z majhnim deležem poškodb dosegle visok fluks vode (28 L/m²h), skoraj dvakrat večji od komercialnih FO membran, ob hkratnem minimalnem povratnem toku topljencev (0,02 g/L). V LPRO procesu so CNM ohranile stabilno nanofiltracijsko selektivnost, z zadrževanjem približno 50 % NaCl skozi več filtracijskih ciklov, kar je primerljivo s komercialnimi membranami. Ti rezultati potrjujejo, da je mogoče molekularno tanke CNM prilagoditi za visoko prepustnost in selektivnost ter s tem nasloviti ključne omejitve obstoječih membran. Kljub obetavnim lastnostim selektivne CNM plasti pa ostajajo izzivi, povezani s TE-PET podporno plastjo. Pri dolgotrajni filtraciji vodnih raztopin je bil opažen postopni upad fluksa vode, zaradi nabrekanja TE-PET. Za zmanjšanje nabrekanja je bila preizkušena površinska funkcionalizacija s trimetilklorosilanom, ki zmanjša hidrofilnost in izboljša stabilnost pretoka skozi membrano. Rezultati potrjujejo, da imajo CNM kompozitne membrane brez prenosa potencial doseči prepustnosti in selektivnosti, primerljive ali celo boljše od konvencionalnih membran. Za prehod v praktično uporabo pa je nujen nadaljnji razvoj, usmerjen v prepoznavanje in odpravljanje ključnih izzivov pri izbiri ustreznih podpornih plasti za posamezne aplikacije ter optimizacijo sinteze CNM plasti z namenom zmanjšanja napak v selektivni plasti.
Keywords:Ogljikova nanomembrana, ciljno jedkana podporna plast, polietilen tereftalat, nabrekanje, proces osmoze, reverzna osmoza.


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