Researcher:
Adatoz, Elda Beruhil

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PhD Student

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Elda Beruhil

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Adatoz

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Adatoz, Elda Beruhil

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2015 - 20194

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Researcher Of Publications: search.filters.isAuthorOfPublication.06a21047-3f9e-4527-bcb1-7e2d6ff4994c

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    Opportunities and challenges of MOF-based membranes in gas separations
    (Elsevier, 2015) Avci, Ahmet K.; N/A; Department of Chemical and Biological Engineering; Adatoz, Elda Beruhil; Keskin, Seda; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548
    Gas separation using metal organic framework (MOF) membranes has become an increasingly important research field over the last years. Several recent studies have shown that thin-film MOF membranes and MOF/polymer composite membranes can outperform well known polymer and zeolite membranes in various gas separation applications. The continuously increasing number of experimental and computational studies emphasizes the superior membrane properties of MOFs. In this review, we present a summary of experimental and computational studies both for thin-film MOF membranes and MOF/polymer composite membranes. We aim to address opportunities and challenges related with use of MOF membranes for gas separations as well as give directions on the requirements for employing these membranes in practical applications. (C) 2015 Elsevier B.V. All rights reserved.
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    Restructuring of poly(2-ethyl-2-oxazoline)/tannic acid multilayers into fibers
    (Royal Society of Chemistry (RSC), 2018) Ow-Yang, C. W.; N/A; N/A; Department of Chemistry; Adatoz, Elda Beruhil; Hendessi, Saman; Demirel, Adem Levent; PhD Student; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Sciences; N/A; N/A; 6568
    H-Bonded, pH-responsive poly(2-ethyl-2-oxazoline) (PEOX) and tannic acid (TA) multilayers were prepared by layer-by-layer deposition. Free-floating PEOX/TA multilayers were shown to restructure in a pH3 phosphate buffer solution to H-bonded, pH-responsive PEOX/TA fibers. This restructuring was also evident during the growth of multilayers thicker than 15 bilayers (BL). The growth profile of 30 BL-thick films showed a significant decrease in the film thickness from 118 nm to 85 nm between 15 BL and 20 BL, after which the growth trend was regained with some small fluctuations. This decrease was associated with the detachment of film patches from the top surface of the film. The rinse solutions consisted of fibrous aggregates, which were formed by the restructuring of the detached multilayer patches. These fibers were characterized by TGA, XPS, FTIR and SEM measurements which showed that the fibers consisted of H-bonded PEOX and TA molecules. As such, the fibers were pH-responsive and disintegrated at pH > 8.5. Scanning electron microscopy images indicated that the fibers might have been formed by the curling of planar LbL film patches and the dried fibers looked like collapsed hollow tubes on solid substrates. These results contribute to our understanding of the stability of LbL films in various chemical conditions and the ways to modify the morphology of self-assembled structures. pH-responsive fibrous aggregates are important in a variety of biomedical applications, from controlled release to sensors.
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    PublicationOpen Access
    Self-assembled poly(2-ethyl-2-oxazoline)/malonic acid hollow fibers in aqueous solutions
    (Elsevier, 2019) Department of Chemistry; Department of Chemical and Biological Engineering; Miko, Annamaria; Altıntaş, Zerrin; Ijaz, Aatif; Demirel, Adem Levent; Adatoz, Elda Beruhil; Teaching Faculty; Researcher; Researcher; Faculty Member; Department of Chemistry; Department of Chemical and Biological Engineering; College of Sciences; Graduate School of Sciences and Engineering; 163509; N/A; N/A; 6568; N/A
    Well-defined poly(2-ethyl-2-oxazoline) (PEOX)/Malonic Acid (MA) fibers having hollow tubular morphology were shown to form in aqueous solutions at 25 degrees C by complexation induced self-assembly between PEOX and MA. The fibers had diameter of similar to 1-3 mu m and a wall thickness of -40 nm. Different interactions between PEOX and MA were identified for complexation as a function of pH. At pI-12, when both ends of MA were protonated, H-bonded complexation was the driving interaction in the fiber formation. IR data showed both PEOX -C=0 band and MA -COOH band in dried fibers formed at pH2. The downshift in the -C=0 stretching of PEOX by as much as 15 cm(-1) confirmed the H-bonded complexation. The interaction enthalpy of PEOX and MA was determined by isothermal titration Calorimetry (ITC) as -49.39 kJ/mol which is consistent with H-bonding. Thermogravimetric analysis (TGA) of the fibers showed two distinct decomposition temperatures one between 100 and 150 degrees C corresponding to MA and the other one at 350-450 degrees C corresponding to PEOX which also indicated the presence of both components in the fibers. At pH4, when one end of MA was protonated and the other end was ionized, electrostatic complexation between carboxylate (-COO-) group of MA and the amide group of PEOX was the driving interaction in the fiber formation. At pH7, when both ends of MA were ionized, fiber formation was significantly hindered. The results are important in understanding the role of different interactions in the hollow fiber formation mechanism as a function of pH. pHresponsive hollow fibers have great potential to be used in biomedical applications for drug delivery and release purposes.
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    PublicationOpen Access
    Application of MD simulations to predict membrane properties of MOFs
    (Hindawi, 2015) Department of Chemical and Biological Engineering; Adatoz, Elda Beruhil; Keskin, Seda; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548
    Metal organic frameworks (MOFs) are a new group of nanomaterials that have been widely examined for various chemical applications. Gas separation using MOF membranes has become an increasingly important research field in the last years. Several experimental studies have shown that thin-film MOF membranes can outperform well known polymer and zeolite membranes due to their higher gas permeances and selectivities. Given the very large number of available MOF materials, it is impractical to fabricate and test the performance of every single MOF membrane using purely experimental techniques. In this study, we used molecular simulations, Monte Carlo and Molecular Dynamics, to estimate both single-gas and mixture permeances of MOF membranes. Predictions of molecular simulations were compared with the experimental gas permeance data of MOF membranes in order to validate the accuracy of our computational approach. Results show that computational methodology that we described in this work can be used to accurately estimate membrane properties of MOFs prior to extensive experimental efforts.