Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Preparation and Characterization of Antifouling Nanofiltration Membranes From a Responsive Pentablock Copolymer(Izmir Institute of Technology, 2018) Çağlar, Nağahan; Alsoy Altınkaya, SacideThe most substantial factor restricting the extensive application of membrane processes is the fouling problem resulting from the deposition of solutes in water on the surface or within the pores of membranes. The frequently used chemical washing procedure to eliminate the fouling issue causes environmental pollution and shortens the membrane life. In order to overcome these disadvantages, the development of membranes possessing low fouling potential is needed. In recent years, the stimuliresponsive polymers have received attention for developing membranes possessing low fouling potential. The antifouling property of these membranes is controlled through the change in their conformation and hydrophilic/hydrophobic characteristics as a response to change in external stimuli such as pH, temperature and ionic strength. The aim of this study was to design antifouling nanofiltration membranes (NF) using a pentablock copolymer which consists of temperature responsive Pluronic F127 (PEO-b-PPO-b- PEO) in the middle block and pH responsive poly(N,N-(diethylamino)ethyl methacrylate) (PDEAEM) in the end blocks. Effects of pH and temperature responsiveness on the membrane fouling were investigated. Fouling tendencies of the membranes were evaluated by using Bovine Serum Albumin (BSA), Alginate (ALG) as organic foulant and Escherichia coli (E.coli) as biological foulant. NF membranes were characterized by scanning electron microscope (SEM), contact angle and zeta potential measurements. It was demonstrated that pentablock copolymer coated membranes displayed antifouling resistance by changing filtration pH and temperature.Master Thesis Development of Thin Film Composite Nanofiltration Membranes With Layer by Layer Polyelectrolyte Deposition(Izmir Institute of Technology, 2017) Tekinalp, Önder; Alsoy Altınkaya, SacideNanofiltration (NF) membranes are usually prepared in thin film composite (TFC) structure through polymerization of various monomers or coating of previously synthesized polymer on porous support membranes. Layer by layer (LbL) deposition of polyelectrolytes on a porous support is a facile and convenient method for the sake of producing NF membranes. This study intends to manufacture TFC NF membrane via alternating polyelectrolyte deposition with limited number of layers on polysulfone/sulfonated polyethersulfone (PSF/SPES) porous support membrane. Polyethyleneimine (PEI) and alginate (ALG) were chosen as polyelectrolyte pairs. The support membranes with different pore sizes were prepared via nonsolvent induced phase inversion method by changing compositions and thickness of casting solution as well as composition of coagulation bath. The polyelectrolytes were deposited dynamically in a dead end filtration module at 1 bar. The influences of supporting electrolyte, polyelectrolyte pH and concentration as well as type of coating method on the membrane performances were investigated. The membranes were characterized by SEM, AFM, staining, and contact angle measurements. Stability and fouling tendency of produced membranes were determined. It was demonstrated that NF membrane (83% PEG1000 rejection) with a high flux (14 L/m2.h.bar) can be manufactured by depositing only a single layer of PEI. Further deposition of ALG on PEI-coated membrane resulted in water permeability of 15.5±0.3 L/m2.h.bar with 89.1±0.6% PEG1000 rejection by adjusting PSF:SPES ratio to 4:1.