Priprava i karakterizacija celulozno acetatnih membrana

undergraduate thesis

• Title (english): Preparation and characterization of cellulose acetate membranes
• Author: Teo Terzić
• Mentor: Krešimir Košutić (mentor)
• Committee member: Krešimir Košutić (predsjednik povjerenstva)
• Committee member: Elvira Vidović (član povjerenstva)
• Committee member: Marko Racar (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2021-09-24, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering

Abstract

Reverzna osmoza (RO) je tehnologija koja se koristi za desalinaciju i pročišćavanje voda pri čemu pod visokim tlakom (40-60 bar) voda učinkovito prolazi kroz polupropusnu membranu, dok sve anorganske i organske otopljene tvari bivaju u najvećoj mogućoj mjeri zadržane na strani RO membrane. Među prvim materijalima koji su se koristili za pripravu RO membrane bio je celulozni acetat (CA). Neki od glavnih nedostataka CA membrane su relativno niska permeabilnost, rad pu uskom neutralnom pH području te podložnost biološkom blokiranju čime se znatno smanjuju performanse membrana. Kako bi se pripremile membrane s poboljšanim svojstvima, provedena je modifikacija CA s
poli(metil-metakrilat-ko-dimetilaminoetil-metakrilatom (P(MMA-ko-DMAEMA). Funkcionalan komonomer MAEMA doprinosi antibakterijskim svojstvima kopolimera koja se dodatno mogu pospješiti kvaternizacijom tercijarnog amina DMAEMA. Dodatkom P(MMA-ko-DMAEMA) moguće je smanjiti utjecaj bioškog blokiranja, odnosno promjene separacijskih i protočnih karakteristika uzrokovanih ovim fenomenom. Cilj ovog rada bio je ispitati utjecaj dodatka kopolimera P(MMA-ko-DMAEMA) u različitim masenim udjelima i termičke obrade na morfologiju asimetričnih celulozno-acetatnih membrana te njihova membranska svojstva. Pripremljene su sljedeće membrane: 17 % i 20 % čisti CDA, 17 % mješavina omjera 95/5 CDA/P(MMA-ko-DMAEMA) te 17 % mješavina 90/10 CDA/ P(MMA-ko-DMAEMA). Utjecaj dodatka kopolimera na karakteristike CDA membrana ispitan je u reverzno osmotskom uređaju. Također, membrane su karakterizirane pomoću infracrvene spektroskopije (IR), mjerenjem kontaktnog kuta i skenirajućeg elektronskog mikroskopa (SEM). Provedene su dvije serije eksperimenata: 1) sirove membrane podvrgnute su tlačnoj obradi, 2) sirove membrane podvrgnute su toplinskoj i tlačnoj obradi. U prvoj seriji eksperimenata membrane pripravljene iz mješavine CDA i P(MMA-ko-DMAEMA) postigle su veći koeficijent zadržavanja soli NaCl i CaCl2 od membrana koje su pripravljene od čistog CDA. Usprkos manjem koeficijentu zadržavanja, membrane pripravljene od čistog CDA pokazale su znatno veće vrijednosti fluksa. U drugoj seriji eksperimenata, termički i tlačno obrađene membrane pokazale su veći koeficijent zadržavanja navedenih soli uz značajno niže vrijednosti fluksa od tlačno obrađenih membrana.

Abstract (english)

Reverse osmosis (RO) is a technology used for desalination and water purification where under high pressure (40-60 bar) water effectively passes through the semipermeable membrane, while all inorganic and organic solutes are retained as much as possible on the side of the RO membrane. Among the first materials used to prepare RO membranes was cellulose acetate (CA). Some of the main disadvantages of CA membranes are relatively low permeability, operation in a narrow neutral pH range and susceptibility to biological fouling, which significantly reduces the performance of membranes.
In order to prepare membranes with improved properties, a modification of CA with the copolymer poly(methyl-methacrylate-co-dimethylaminoethyl-methacrylate,
P(MMA-co-DMAEMA) was carried out. The functional comonomer DMAEMA contributes to the antibacterial properties of the copolymer, which can be further enhanced by quaternization of the tertiary amine of DMAEMA. By adding P(MMA-co-DMAEMA) it is possible to reduce the effect of biological fouling i.e., changes in separation and flow properties caused by this phenomenon. The aim of this study was to investigate the effects of adding P(MMA-co-DMAEMA) copolymer in different mass fractions and heat treatment on the morphology of asymmetric cellulose acetate membranes and their performance. The following membranes were prepared: 17 % and 20 % pure CDA, 17 % blends of 95/5 CDA and P(MMA-co-DMAEMA), and 17 % blends of 90/10 CDA and P(MMA-co-DMAEMA). The effect of the addition of the copolymer on the properties of the CDA membranes was studied in a reverse osmotic apparatus. In addition, the membranes were characterized using infrared spectroscopy (IR), contact angle measurements and a scanning electron microscope. Two series of experiments were conducted: 1) the raw membranes were subjected to pressure treatment, 2) the raw membranes were subjected to heat and pressure treatment. In the first series of experiments, the membranes prepared from a mixture of CDA and P (MMA-co-DMAEMA) obtained a higher retention coefficient for NaCl and CaCl2 than the membranes prepared from pure CDA. Despite the lower retention coefficient, the membranes prepared from pure CDA exhibited significantly higher flux values. In the second series of experiments, thermally and pressure treated membranes showed a higher retention coefficient for salts with significantly lower flux values than the pressure treated membranes.

• Keywords: celulozni diacetat; poli(metil-metakrilata-ko-dimetilaminoetil-metakrilat; reverzno osmotske membrane
• Keywords (english): cellulose diacetate; poly(methyl-methacrylate-co-dimethylaminoethyl-methacrylate; reverse osmotic membranes
• Language: croatian
• URN:NBN: urn:nbn:hr:149:678804
• Study programme: Title: Chemical Engineering - Undergraduate study; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2023-04-27 13:33:09