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Title:POVRŠINSKA MODIFIKACIJA NANOFILTRACIJSKIH MEMBRAN Z ALKOKSISILANI ZA ODSTRANJEVANJE IONOV TEŽKIH KOVIN
Authors:ID Bauman, Maja (Author)
ID Lobnik, Aleksandra (Mentor) More about this mentor... New window
ID Roš, Milenko (Comentor)
Files:.pdf DR_Bauman_Maja_2010.pdf (8,38 MB)
MD5: CF5218D7AAEB2C44121A404CFB8299E3
PID: 20.500.12556/dkum/9d2a0116-7b6d-4f45-a834-e6a35f0856d2
 
Language:Slovenian
Work type:Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Ioni težkih kovin, kot so Zn2+, Cd2+, Pb2+, Ni2+, Cu2+, Mn2+, Hg2+, Co2+, Al3+, Fe3+, Cr6+,… največkrat končajo v okolju kot posledica izpustov industrijskih odpadnih vod. Povzročajo onesnaženost tal in površinskih voda ter zaradi ekotoksikoloških lastnosti posledično vplivajo na zdravje živih organizmov. Njihovo odstranjevanje z membranskimi tehnologijami s pomočjo ustrezne nanofiltracijske (NF) membrane je sicer učinkovito, vendar učinkovitost NF membran, zlasti tistih, ki so trenutno dostopne na trgu, zaradi lastnosti materiala in procesa iz katerega so izdelane, variira. Površinska modifikacija membran z alkoksisilanskimi prekurzorji po sol-gel postopku v smislu dodatnega površinskega nanosa lahko dodatno stabilizira membrano, predvsem pa izboljša selektivno odstranjevanje specifičnih težkih kovin zaradi steričnih ovir, elektrosteričnih lastnosti in funkcionalnih skupin z afiniteto do ionov težkih kovin nanesenih na površino membrane. V okviru raziskav je bila izvedena osnovna karakterizacija izbrane tanko slojne kompozitne NF membrane (NF2, Sepro Inc.). Po sol-gel postopku pripravljeni soli, uporabljeni za nanos na membrano, so vsebovali čiste komponente in mešanice alkoksisilanskih prekurzorjev tetraetoksisilana (TEOS), 3-(trimetoksisililpropil)dietilentriamina (DETA), 3-(merkaptopropil)trimetoksisilana (MPTMS), v molarnih razmerjih voda:prekurzor (r525, r264 in r175) in kombinacije prekurzorjev v razmerjih 1:1; 1:2, 1:4; 2:1 in 4:1, in sicer v alkalnem in kislem pH mediju (~4,5 in ~10), v času od 1 do 14 ur in temperaturah od 25 °C do 50 °C. Lastnosti pripravljenih solov in modificiranih membran so bile ovrednotene z različnimi karakterizacijskimi metodami. Namen osnovnih raziskav je bil preučiti vpliv parametrov priprave in nanosa sol-gela (tip in koncentracija sol-gel prekurzorja, katalizator, molsko razmerje voda:prekurzor, staranje sola, čas priprave sola) na končno mikrostrukturo površinske modifikacije. Karakterizacija sol-gel alkoksidnih materialov in površinskega sloja obdelanih membran je podlaga za podatke o parametrih, ki vplivajo na učinek zadrževanja ionov težkih kovin (Zn2+, Cd2+, Hg2+, Pb2+). Površinsko modificirane membrane z najboljšim sol-gel nanosom so bile testirane v smislu učinkovitosti odstranjevanja ionov težkih kovin in modelnih vod pri različnih filtracijskih pogojih. Iz rezultatov filtracije je razvidno, da je karakterizacija nemodificirane, komercialno dostopne tankoplastne kompozitne nanofiltracijske membrane kot njeno pomanjkljivost pokazala nestabilno strukturo in nihajoče rezultate v zadrževanju ionov in molekul različnih velikosti in mas. Z izbranimi alkosisilanskimi prekurzorji (TEOS, DETA in MPTMS) je iz sol-gela z optimizacijo pogojev sinteze in sestave sola moč formirati funkcionalne delce z afiniteto do membrane in ionov težkih kovin ter iz njih tvoriti funkcionalen in obstojen monoplastni nanos na izbrano membrano. Rezultati kažejo, da je površinska modifikacija NF membran lahko učinkovita v smislu selektivnega zadrževanja ionov težkih kovin, predvsem zadrževanje Hg2+ in Pb2+ ionov se izboljša z uporabo kombinacije prekurzorjev TEOS:MPTMS in TEOS:DETA v razmerju 1:1 in temperaturi 50 °C, ter TEOS-a z r525 pri sobni temperaturi. Z eksperimenti filtracije na pilotni filtracijski napravi je bilo dokazano, da je z modifikacijo membrane v smislu nanosa dodatne funkcionalne plasti, formirane iz delcev izbranih alkosisilanskih prekurzorjev po metodi sol-gel možno bistveno (za več kot 100% za Hg2+ in za do 10% za Pb2+) izboljšati selektivnost in stabilnost strukture izbrane nanofiltracijske membrane. Obsežno eksperimentalno delo, katerega rezultati so spremljani in dokazani s premišljeno izbranimi analiznimi metodami (SEM/TEM/EDXS mikroskopija; ATR-FTIR spektroskopija, meritve zeta potenciala koloidov; atomska absorpcijska spektroskopija), dajejo veliko možnosti za nadaljnje raziskave in izboljšave. Modifikacije površin TFC membran predstavljajo izvirni doprinos k novi razvojni perspektivi na področju
Keywords:tankoplastne kompozitne membrane, nanofiltracija, površinska modifikacija, alkoksisilani, tetraetoksisilan, 3-(trimetoksisililpropil)dietilentriamin, 3-(merkaptopropil)trimetoksisilan, ioni težkih kovin, cink, kadmij, živo srebro, svinec
Place of publishing:[Maribor
Publisher:M. Bauman]
Year of publishing:2010
PID:20.500.12556/DKUM-17060 New window
UDC:628.353:542.816(043.3)
COBISS.SI-ID:254125824 New window
NUK URN:URN:SI:UM:DK:EOQBUVUL
Publication date in DKUM:21.12.2010
Views:4212
Downloads:430
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
:
BAUMAN, Maja, 2010, POVRŠINSKA MODIFIKACIJA NANOFILTRACIJSKIH MEMBRAN Z ALKOKSISILANI ZA ODSTRANJEVANJE IONOV TEŽKIH KOVIN [online]. Doctoral dissertation. Maribor : M. Bauman. [Accessed 29 March 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=17060
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Secondary language

Language:English
Title:SURFACE MODIFICATION OF NANOFILTRATION MEMBRANES WITH ALKOXYSILANES FOR HEAVY METAL ION REMOVAL
Abstract:Heavy metal ions, such as Zn2+, Cd2+, Pb2+, Ni2+, Cu2+, Mn2+, Hg2+, Co2+, Al3+, Fe3+, Cr6+,… are mainly discharged into the environment as industrial wastewaters, causing serious soil and water pollution and consequently effect the health of living organisms due to ecotoxical properties. Their removal is achievable with membrane technologies, by using appropriate nanofiltration membrane. Since NF membrane’s efficiency varies regarding the material used and preparation process of the manufacturer, surface modification with alkoxysilanes via sol-gel process seems promising for a more successful selective removal of heavy metal ions. Surface modification of membranes by alkoxysilane precursors via sol-gel process in terms of additional surface coating can further stabilize the membrane, and particularly improve the selective removal of specific heavy metals due to steric effects, electrosteric properties and functional groups with a tendency to heavy metal ions on the surface membrane. The research was focused on the basic characterization of the selected thin-film composite NF membrane (NF2, Inc. Sepro.). Sols were prepared in accordance with the sol-gel process pure and combined components of alkoxysilane precursors, i.e. tetraethoxysilane (TEOS), 3-(trimethoxysilylpropyl)diethylenetriamine (DETA), 3-(mercaptopropyl)trimethoxysilane (MPTMS) for particle. Sol formation was based on water-to-precursor ratio: (r525, r264 and r175) and combinations of precursors in the proportions 1:1, 1:2, 1:4, 2:1 and 4:1, in alkaline and acidic pH medium (~4.5 and ~10), from 1 to 14 hours aging time and temperatures from 25 °C to 50 °C. Prepared sols and modified membranes were characterized via several different characterization techniques. The purpose of basic research was to examine the parameters effect of preparation and sol-gel coating (type and concentration of sol-gel precursor, catalyst, molar ratio water to precursor, sol aging, and preparation time of sol) on the final microstructure of membrane surface modification. Based on the analyzed properties of sol-gel alkoxide materials and surface layer of the modified membranes, information of the basic parameters that influence the effect of retention of heavy metals ions (Zn2+, Cd2+, Hg2+, Pb2+) from wastewater was obtained. Surface-modified membranes with the best sol-gel coatings were tested for efficiency of heavy metal ions removal using model water at various filtration conditions. The characterization results of non-modified, commercially available thin-film composite nanofiltration membrane showed an unstable structure and varying retention rates of ions and molecules of different sizes and weights as its drawback. Selected alkoxysilane precursors (TEOS, DETA and MPTMS) forming coatings in sol-gel process with optimized sol composition under optimized sol-gel procedure enable to form the functional particles with affinity to membranes and to heavy metal ions and to apply them as a functional and stable monolayer onto the selected membrane. The results of the filtration show that the surface modification of NF membranes can be effective in terms of selective retention of heavy metal ions. Particularly the selective retention of Hg2+ and Pb2+ ions is improved by using a combination of precursor TEOS:MPTMS and TEOS:DETA 1:1 ratio, at temperature 50 °C, and TEOS with a r525 at room temperature. The filtration experiments using a laboratory scale filtration unit demonstrated that by modifying the membrane in terms of application of additional functional layers, formed of particles on the basis of selected alkoxysilane precursors by the sol-gel method, the selectivity and stability of selected TFC nanofiltration membrane can be significantly improved (more than 100% for Hg2+ and up to 10% the Pb2+). Extensive experimental work, the results of which are monitored and proven by selected analytical methods (SEM/TEM/EDXS microscopy, ATR-FTIR spectroscopy, measurements of zeta potential of colloids, atomic absorption spectroscopy), lead to great opportunities for furthe
Keywords:Thin film composite membranes, Nanofiltration, Surface modification, Sol-gel, Alkoxysilanes, Tetraethoxysilane, 3-(trimethoxysilylpropyl)diethylenetriamine, 3-(mercaptopropyl)trimethoxysilane, Heavy metal ions, Zinc, Cadmium, Mercury, Lead


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