Browsing by Author "Yalcinkaya, Baturalp"

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    Electrospun Polyamide-6 Nanofiber Hybrid Membranes for Wastewater Treatment
    (2019-01-01) Yalcinkaya, Fatma; Yalcinkaya, Baturalp; Hrůza, Jakub
    Electrospun nanofiber hybrid membranes have superior membrane performance due to their high specific surface area, narrow pore size, high porosity, and uniform pore size. Recently, increasing attention has been given to hydrophilic membranes such as polyamide 6 (PA6) in applications microfiltration and reverse osmosis. Electrospun PA6 nanofiber hybrid membranes have not found any real application due to their poor mechanical strength under high pressure. In this study, PA6 nanofiber layer was prepared using wire electrospinning method. Three supporting material with different adhesion method has been used to improve the mechanical properties of the membranes. Membranes were characterized with Scanning Electron Microscope images, pore size, and contact angle measurements. Tensile strength and the delamination tests were run to measure the mechanical properties of the membranes. Three types of wastewater were carried out during filtration; using real wastewater supplied from a company which consists of pitch and tar oils, engine oil/water mixture and kitchen oil/water mixture. Results indicated that the adhesion method and the supporting layer played a big role in the permeability of the membranes. The PA6 nanofiber hybrid membranes exhibited high water fluxes in even at low pressures which indicate that electrospun nanofiber membranes might be highly promising for microfiltration applications.
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    Influence of Salts on Electrospinning of Aqueous and Nonaqueous Polymer Solutions
    (Technická Univerzita v Liberci, 2015-01-01) Yalcinkaya, Fatma; Yalcinkaya, Baturalp; Jirsák, Oldřich
    A roller electrospinning system was used to produce nanofibres by using different solution systems. Although the process of electrospinning has been known for over half a century, knowledge about spinning behaviour is still lacking. In this work, we investigated the effects of salt for two solution systems on spinning performance, fibre diameter, and web structure. Polyurethane (PU) and polyethylene oxide (PEO) were used as polymer, and tetraethylammonium bromide and lithium chloride were used as salt. Both polymer and salt concentrations had a noteworthy influence on the spinning performance, morphology, and diameter of the nanofibres. Results indicated that adding salt increased the spinnability of PU. Salt created complex bonding with dimethylformamide solvent and PU polymer. Salt added to PEO solution decreased the spinning performance of fibres while creating thin nanofibres, as explained by the leaky dielectric model.
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    On the Nature of Electric Current in the Electrospinning Process
    (Hindawi Publishing Corporation, 2013-01-01) Yalcinkaya, Baturalp; Yener, Fatma; Jirsák, Oldřich; Cengiz-Callioglu, Funda
    The electric currents between electrodes in the electrospinning process are based on the movement of charge carriers through the spinning space. The majority of the charge carriers are formed by ionization of the air close to the metallic needle and to the polymer jet. The salt contained in the polymer solution contributes to the concentration of charge carriers, depending on its amount. The conductivity of polymer jets does not significantly affect the current since the jets do not link the electrodes.
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    Separation of racemic compound by nanofibrous composite membranes with chiral selector
    (ELSEVIER, RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS, 2020-02-15) Gaálová, Jana; Yalcinkaya, Fatma; Cuřínová, Petra; Kohout, Michal; Yalcinkaya, Baturalp; Koštejn, Martin; Jirsák, Jan; Stibor, Ivan; Bara, Jason E.; Van der Bruggen, Bart; Izák, Pavel
    A series of unique composite membranes formed from a nano&fibrous material with different amounts of a chiral selector was used for separation of chiral drugs. The membrane performances were demonstrated through sorption tests, wherein they were soaked in an aqueous solution of racemic D, L-tryptophan (a model chiral drug). The changes in concentration of both enantiomers over time were monitored by HPLC analysis. During 100 days, a blank membrane (without the chiral selector) exhibited no sorption activity. The membranes containing the selector had no influence on the amount of D-enantiomer, while the L-enantiomer was preferentially adsorbed on each membrane. The intensity of the sorption was found to be a direct function of the amount of the selector contained in a particular membrane. The separation of the same model chiral compound was further studied in diffusion cells by pertraction. The preferential sorption of L-tryptophan in the feed underlined the crucial importance of the selector in an active layer in view of chiral recognition of enantiomers. Due to the exclusive membrane material, the retention of L-tryptophan in the membrane materials did not block the passage of D-enantiomer into the permeate at any point during the experiment. Moreover, the nanomaterial in the active layer assured the distribution of the selector to the point that only 50% of (S, S)-1,2-diaminocyclohexane in one part of the active layer was sufficient to achieve 99% of enantioselectivity. The membranes - fresh and used - were analysed by Fourier-transform infrared (FTIR) spectroscopy and characterized by scanning electron microscopy (SEM) confirming the stability of the tested membranes. To complete the study, the role of the polyamide active layer in chiral recognition of tryptophan enantiomers was proposed.