Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 63Citation - Scopus: 65Amidoxime Functionalized Polymers of Intrinsic Microporosity (pim-1) Electrospun Ultrafine Fibers for Rapid Removal of Uranyl Ions From Water(Elsevier Ltd., 2019) Satılmış, Bekir; Isık, Tuğba; Demir, Mustafa Muammer; Uyar, TamerThe Polymers of Intrinsic Microporosity (PIM-1) is considered as one of the most promising polymer candidates for adsorption applications owing to its high surface area and the ability to tailor the functionality for the targeted species. This study reports a facile method for the preparation of amidoxime functionalized PIM-1 fibrous membrane (AF-PIM-FM) by electrospinning technique and its practical use for the extraction of U(VI) ions from aqueous systems via column sorption under continuous flow. Fibrous membrane form of amidoxime functionalized PIM-1 (AF-PIM-FM) was prepared by electrospinning method owing to its excellent processability in dimethylformamide. Bead-free and uniform fibers were obtained as confirmed by SEM imaging and average fiber diameter was 1.69 +/- 0.34 mu m for AF-PIM-FM. In addition, electrospun PIM-1 fibrous membrane (PIM-FM) was prepared as a control group. Structural and thermal characterization of powder and membrane forms of the materials were performed using FT-IR, H-1 NMR, XPS, Elemental analyses, TGA, and DSC. The porosity of the samples was measured by N-2 sorption isotherms confirming amidoxime PIM-1 still maintain their porosity after functionalization. Amidoxime functionality along with membrane structure makes AF-PIM-FM a promising material for uranyl adsorption. First, a comparison between powder and membrane form of amidoxime functionalized PIM-1 was investigated using batch adsorption process. Although membrane form has shown slightly lower adsorption performance in the batch adsorption process, the advantage of using the membrane in column adsorption processes makes membrane form more feasible for real applications. In addition, amidoxime modification enhanced the uranium adsorption ability of PIM-FM up to 20 times. The effect of initial concentration and pH were investigated along with regeneration of the adsorbents. AF-PIM-FM was successfully used for five adsorption-desorption cycles without having any damage on the fibrous structure.Article Citation - WoS: 49Citation - Scopus: 55A Facile Approach for Preparation of Positively Charged Nanofiltration Membranes by In-Situ Crosslinking Between Polyamide-Imide and Polyethylenimine(Elsevier Ltd., 2018) Cihanoğlu, Aydın; Alsoy Altınkaya, SacidePolyamide-imides (PAI) are attractive materials for membrane formation due to their high chemical and thermal stability. In this study, we report a facile approach for preparing positively charged nanofiltration (NF) membranes using a one-step process. Polyethylenimine (PEI) was dissolved in a coagulation bath and formed in-situ ionic crosslinking with PAI during phase inversion. The membranes were characterized by attenuated total reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), atomic force microscopy (AFM), contact angle and zeta potential measurements. The most positively charged membrane was obtained when the pH of the coagulation bath was adjusted to 10. This membrane showed a significant decrease in contact angle and surface roughness and increase in the pure water permeability (PWP) compared to the plain PAI membrane. The salt rejection performance of the crosslinked PAI membrane was measured using MgCl2, CaCl2, NaCl and Na2SO4 salts. The rejection of Mg2+ and Ca2+ ions was found to be 95.6% and 90.2%, respectively. The crosslinked membrane showed excellent chemical stability when stored in HCl solution at pH 3 up to 7 days. Antifouling behaviour of the optimized membrane was tested using bovine serum albumin (BSA) and flux recovery ratio of the membrane was found to be 92.2% at the end of 3 h filtration. The results suggest that the positively charged PAI membranes crosslinked with PEI may have a potential in recovering valuable cationic metals from acid mine wastewater.Article Citation - WoS: 62Citation - Scopus: 72Diatomite Reinforced Chitosan Composite Membrane as Potential Scaffold for Guided Bone Regeneration(Elsevier Ltd., 2017) Tamburacı, Sedef; Tıhmınlıoğlu, FundaIn this study, natural silica source, diatomite, incorporated novel chitosan based composite membranes were fabricated and characterized for bone tissue engineering applications as possible bone regeneration membrane. The effect of diatomite loading on the mechanical, morphological, chemical, thermal and surface properties, wettability and in vitro cytotoxicity and cell proliferation on of composite membranes were investigated and observed by tensile test, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), protein adsorption assay, air/water contact angle analysis and WST-1 respectively. Swelling studies were also performed by water absorption capacity determination. Results showed that incorporation of diatomite to the chitosan matrix increased the surface roughness, swelling capacity and tensile modulus of membranes. An increase of about 52% in Young's modulus was achieved for 10 wt% diatomite composite membranes compared with chitosan membranes. High cell viability results were obtained with indirect extraction method. Besides, in vitro cell proliferation and ALP activity results showed that diatom incorporation significantly increased the ALP activity of Saos-2 cells cultured on chitosan membranes. The novel composite membranes prepared in the present study with tunable properties can be considered as a potential candidate as a scaffold in view of its enhanced physical & chemical properties as well as biological activities for bone tissue engineering applications.Article Citation - WoS: 66Citation - Scopus: 73Novel Low-Fouling Membrane Bioreactor (mbr) for Industrial Wastewater Treatment(Elsevier Ltd., 2016) Deowan, Shamim Ahmed; Galiano, Francesco; Hoinkis, Jan; Johnson, Daniel; Alsoy Altınkaya, Sacide; Gabriele, Bartolo; Hilal, Nidal; Drioli, Enrico; Figoli, AlbertoA novel antifouling coating of ultrafiltration (UF) commercial membranes, based on a polymerisable bicontinuous microemulsion (PBM) technique, was developed and tested for the first time in a membrane bioreactor (MBR) using an artificial model textile dye wastewater and compared with a commercial uncoated UF membrane. The results showed that the commercial MBR module faced severe fouling problems whereas the novel coated PBM MBR module reduced the fouling significantly. The analysis of fouling rate using a resistance model confirms that PBM coated membrane has a higher antifouling effect. The antimicrobial properties of the PBM membrane contributed by polymerisable cationic surfactant acryloyloxyundecyltriethylammonium bromide (AUTEAB) guaranteed an anti-biofouling effect preventing the growth of microorganisms on the membrane surface. In addition, the PBM MBR module showed 10±1% higher blue dye removal efficiency and a similar rate of COD removal efficiency of about 95±1% compared to commercial module. However, water permeability was slightly lower due to extra resistance of the PBM coating. Root mean squared (RMS) roughness measurement and analysis of AFM images confirmed that the stable novel membrane coating still existed and showed antimicrobial effect even after 105 days of operation. The results obtained demonstrated the potential of the low fouling PBM membrane.Article Citation - WoS: 13Citation - Scopus: 15Ancillary Effects of Surfactants on Filtration of Low Molecular Weight Contaminants Through Cellulose Nitrate Membrane Filters(Elsevier Ltd., 2016) Olcay, Aybike Nil; Polat, Mehmet; Polat, HürriyetRemoval of contaminants with low molecular weight (<800 Dalton) requires the use of advanced separation techniques such as ultrafiltration (UF) or micellar enhanced ultrafiltration (MEUF). However, surface active agents invariably co-exist in waste waters along with these contaminants or they may be added intentionally as part of the separation process as in the case of MEUF. Though it is quite likely that both the filter medium and the contaminants would interact with the surfactant molecules or their micelles, there is not sufficient emphasis in the literature on the concomitant aspects of such interactions.The ancillary effects created by anionic (sodium dodecyl sulfate, SDS), cationic (hexadecyltrimethyl ammonium bromide, CTAB) and non-ionic (ethoxylated octylphenol, TX-100) surfactants on the mechanism and efficiency of the filtration process were investigated in this study. Methylene blue (MB) and cellulose nitrate membrane (CNM) filters were employed as model retentate and the separation medium. A combination of surface tension, contact angle and charge measurements demonstrated that the addition of surfactants had a remarkable effect on the filtration outcome. The effect depended on both the type and concentration of the surfactant and was manifested mainly through the creation of MB-surfactant entities which acted differently than the MB alone; but more importantly, through the interactions of the surfactant molecules/micelles and the MB-surfactant pairs with the separation membrane.Article Citation - WoS: 52Citation - Scopus: 60A Step Forward To a More Efficient Wastewater Treatment by Membrane Surface Modification Via Polymerizable Bicontinuous Microemulsion(Elsevier Ltd., 2015) Galiano, Francesco; Figoli, Alberto; Deowan, Shamim Ahmed; Johnson, Daniel; Alsoy Altınkaya, Sacide; Veltri, Lucia; De Luca, Giorgio; Mancuso, Raffaella; Hilal, Nidal; Gabriele, Bartolo; Hoinkis, JanAn innovative hydrophilic and anti-fouling coating material for application in membrane technology for wastewater treatment has been developed by polymerization of a polymerizable bicontinuous microemulsion (PBM) and used for surface modification of a commercial flat polyethersulfone (PES) membrane. The novel nanostructured coating has been produced using acryloyloxyundecyltriethylammonium bromide (AUTEAB) as a co-polymerizable surfactant, obtained through a synthetic method characterized by a lower cost and a higher reproducibility compared to other known polymerizable surfactants. The novel composite membranes have been characterized and compared with the uncoated PES membranes. Coated membranes resulted in a smoother surface and a higher hydrophilicity with respect to the uncoated ones, and showed a particular nano-size channel-like morphology making them highly resistant to the fouling phenomenon. The covalent anchorage of the surfactant on the membrane surface ensured the embedment of the molecule in the polymeric matrix avoiding its leaching and also leading the coated membranes to have significant antimicrobial activity, which is very important for reducing the biofouling phenomenon.All these aspects make the tailored coating material an ideal and efficient coating for modifications of commercial membrane surfaces, to be used in membrane processes in wastewater treatment.Article Citation - WoS: 6Citation - Scopus: 7Modeling of Asymmetric Membrane Formation by a Combination of Dry/Wet Phase Inversion Processes(Elsevier Ltd., 2006) Alsoy Altınkaya, SacideThe invention of asymmetric polymer membranes by Loeb and Sourirajan has caused an enormous growth in the field of membrane science and technology. Application areas range from chemical, biomedical to biotechnology industries. Asymmetric membranes are mostly fabricated by a process called phase inversion which can be achieved through four principal methods: immersion precipitation (wet phase inversion), vapor-induced phase separation, thermally induced phase separation and dry-casting. In these techniques, an initially homogeneous polymer solution becomes thermodynamically unstable and phase separates into polymerlean and polymer-rich phases. Structure of these types of membranes is greatly influenced by even slight change in membrane preparation conditions.Article Citation - WoS: 100Cholesterol Dictates the Freedom of Egf Receptors and Her2 in the Plane of the Membrane(Elsevier Ltd., 2013) Orr, Galya; Hu, Dehong; Özçelik, Serdar; Wiley, H. Steven; Colson, Steven D.; Opresko, Lee K.The flow of information through the epidermal growth factor receptor (EGFR) is shaped by molecular interactions in the plasma membrane. The EGFR is associated with lipid rafts, but their role in modulating receptor mobility and subsequent interactions is unclear. To investigate the role of nanoscale rafts in EGFR dynamics, we used single-molecule fluorescence imaging to track individual receptors and their dimerization partner, human epidermal growth factor receptor 2 (HER2), in the membrane of human mammary epithelial cells. We found that the motion of both receptors was interrupted by dwellings within nanodomains. EGFR was significantly less mobile than HER2. This difference was likely due to F-actin because its depolymerization led to similar diffusion patterns between the EGFR and HER2. Manipulations of membrane cholesterol content dramatically altered the diffusion pattern of both receptors. Cholesterol depletion led to almost complete confinement of the receptors, whereas cholesterol enrichment extended the boundaries of the restricted areas. Interestingly, F-actin depolymerization partially restored receptor mobility in cholesterol-depleted membranes. Our observations suggest that membrane cholesterol provides a dynamic environment that facilitates the free motion of EGFR and HER2, possibly by modulating the dynamic state of F-actin. The association of the receptors with lipid rafts could therefore promote their rapid interactions only upon ligand stimulation.