Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Institution Author: search.filters.institutionAuthor.Alsoy Altınkaya, SacideWoS Q: search.filters.wosQuartile.Q1

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Now showing 1 - 10 of 29
  • Article
    Citation - WoS: 12
    Citation - Scopus: 12
    Biofouling-Resistant Ultrafiltration Membranes Via Codeposition of Dopamine and Cetyltrimethylammonium Bromide With Retained Size Selectivity and Water Flux
    (American Chemical Society, 2022) Cihanoğlu, Aydın; Schiffman, Jessica D.; Alsoy Altınkaya, Sacide
    Biofouling is a serious problem in ultrafiltration (UF) membrane applications. Modifying the surface of membranes with low molecular weight, commercially available antibacterial chemistries is an excellent strategy to mitigate biofouling. Herein, we report a new strategy to impart antibacterial and anti-biofouling behavior without changing the support membrane’s size selectivity and pure water permeance (PWP). To this end, a strong antibacterial agent, cetyltrimethylammonium bromide (CTAB), was codeposited with dopamine onto commercial polyethersulfone (PES) UF membranes in the presence of nitrogen (N2) gas backflow. The PWP and pore size of the support membrane did not change with codeposition, confirming the benefit of N2 backflow in mitigating the solution intrusion phenomenon. X-ray photoelectron spectroscopy (XPS), surface ζ potentials, and contact angle measurements confirmed the successful codeposition of polydopamine (PDA) and CTAB onto the membrane. Among three different CTAB concentrations systematically investigated, the membrane functionalized with CTAB at the critical micelle concentration (CMC) provided the best anti-biofouling activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and retained its surface ζ potential after being stored in 1 M NaCl (pH = 6.8) for 3 months. Our results demonstrate the potential of using a facile, one-step approach to modify commercial UF membranes without compromising their pore size or flux, while simultaneously endowing antibacterial activity.
  • Article
    Citation - WoS: 54
    Citation - Scopus: 62
    A Positively Charged Loose Nanofiltration Membrane Fabricated Through Complexing of Alginate and Polyethyleneimine With Metal Ions on the Polyamideimide Support for Dye Desalination
    (Elsevier, 2021) Metecan, Ayşe; Cihanoğlu, Aydın; Alsoy Altınkaya, Sacide
    Nowadays, loose nanofiltration (NF) membranes are preferred for dye desalination to achieve high dye/salt selectivity and enable filtration at low operating pressure. However, current fabrication techniques require rigorous reaction conditions and long preparation times. Herein, we used the chelating ability of the polyethyleneimine (PEI) and alginate with the metal ions to fabricate loose NF membranes via a facile approach. The positively charged polyamide imide (PAI)/PEI support was used to build the assembly. Direct attachment of Zn or Fe ions to the PEI chains did not result in a stable complex in the presence of a high salt concentration (1000 ppm NaCl). On the other hand, alginate coated on the support allowed building permanent assemblies after crosslinked with Fe3+ and Zn2+ transition metal ions. The PAI/PEI-Alg-Fe3+ membrane exhibited the highest permeability, excellent antifouling behaviour upon exposure to synthetic textile wastewater, and maintained long-term stability under static and dynamic conditions. Also, the same membrane rejected dyes and coloured substances in real wastewater sample during 72 h continuous filtration. With alginate metal complex formation on a suitable support, a scalable loose NF membrane was manufactured, demonstrating improved throughput value compared to current NF membranes.
  • Article
    Citation - WoS: 50
    Citation - Scopus: 51
    A Facile Route To the Preparation of Antibacterial Polysulfone-Sulfonated Polyethersulfone Ultrafiltration Membranes Using a Cationic Surfactant Cetyltrimethylammonium Bromide
    (Elsevier, 2020) Cihanoğlu, Aydın; Alsoy Altınkaya, Sacide
    Cetyltrimethylammonium bromide (CTAB), a cationic surfactant, is known to have strong bactericidal potential. In this study, we report a facile approach for preparing CTAB-containing polysulfone-sulfonated polyethersulfone (PSF-SPES) based ultrafiltration membranes with antibacterial properties. The CTAB was added in gelation medium at three different concentrations and made an electrostatic interaction with SPES at the polymer/bath interface during phase inversion. The successful incorporation of the CTAB in the membrane structure was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The CTAB-containing membranes had higher contact angle, lower pure water permeability (PWP) and molecular weight cut-off than the pristine membrane. The membranes prepared at critical and above critical micelle concentration (CMC) of the CTAB showed excellent antibacterial activity on both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. On the other hand, the PWP of the membrane decreased from 93 +/- 1.6 to 39.3 +/- 3.2 L/m(2) h bar upon increasing the CTAB concentration from 10(-3) M (=CMC) to 10(-2) M, consequently, CMC was chosen as the optimal concentration. The membrane prepared at the CMC displayed almost 100% flux recoveries after dynamic bacteria filtration followed by simple rinsing with PBS solution. Leaching experiments continued up to 30 days demonstrated that 96% of the CTAB remained in this membrane. Furthermore, at the end of 1 month of storage in 1 M NaCl solution, no change was observed in the antibacterial activity of this membrane compared to fresh membrane. These findings emphasize the potential of the facile approach proposed in this study to develop antibacterial ultrafiltration membranes in a single step.
  • Article
    Citation - WoS: 28
    Citation - Scopus: 29
    Development of a High-Flux Thin-Film Composite Nanofiltration Membrane With Sub-Nanometer Selectivity Using a Ph and Temperature-Responsive Pentablock Co-Polymer
    (American Chemical Society, 2019) Bar, Canbike; Çağlar, Nagahan; Uz, Metin; Mallapragada, Surya K.; Alsoy Altınkaya, Sacide
    Producing block co-polymer-based nanofiltration (NF) membranes with sharp molecular weight cutoffs via an efficient method exhibiting persistent size-based separation quality is challenging. In this study, this challenge was addressed by reporting a facile approach to fabricate pentablock co-polymer (PBC)-based thin-film composite (TFC) NF membranes. The PBC, consisting of temperature-responsive Pluronic F127 (PEO-b-PPO-b-PEO) middle blocks and pH-responsive poly(N,N-(diethylamino)ethyl methacrylate) end blocks, were synthesized by atom-transfer radical polymerization. This polymer was then attached electrostatically to the surface of polysulfone/sulfonated polyether-sulfone support membranes fabricated using a non-solvent-induced phase separation technique. The conformational changes of the PBC chains in response to pH and temperature determined the, pure water flux and neutral solute (PEG 1000) rejection performance of TFC membranes. Permeability of the membranes increased from 13.0 +/- 0.63 to 15.9 +/- 0.06 L/m(2).h bar and from 6.7 +/- 0.00 to 13.9 +/- 0.07 L/m(2).h.bar by changing the solution pH from 4 to 8.5 and temperature from 4 to 25 degrees C, respectively. The pH- and temperature-responsive conformational changes did not affect the PEG 1000 rejection and membrane pore radius, which remained constant at similar to 89% and similar to 0.9 nm, respectively. This important finding was attributed to the high grafting density of co-polymer chains, resulting in spatial limitations among the grafted chains. The pore size of similar to 0.9 nm achieved with the proposed membrane design is the smallest size reported so far for membranes fabricated from block copolymers. TFC membranes demonstrated high stability and maintained their flux and rejection values under both static (storage in an acidic solution for up to 1 month) and dynamic (filtering PEG 1000 solution over 1 week) conditions. Pentablock copolymers enable a NF membrane with a sharp molecular weight cutoff suitable for size-selective separations. The membrane fabrication technique proposed in this study is a scalable and promising alternative that does not involve complex synthetic routes.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 16
    A High-Performance Acid-Resistant Polyaniline Based Ultrafiltration Membrane: Application in the Production of Aluminium Sulfate Powder From Alumina Sol
    (Elsevier, 2020) Güngörmüş, Elif; Alsoy Altınkaya, Sacide
    In this work, we report a new class of acid-resistant ultrafiltration membrane fabricated from polyaniline (PANI) based on its self-acid doping ability. The doped membrane was prepared by filtering the H2SO4 solution (pH = 0.55) through the PANI membrane at 2 bar. To critically assess the acid resistance, the resulting doped membrane was stored in H2SO4 solution (pH = 0.55) for one month. The chemical structure and separation performance of the membrane was not adversely affected by acid exposure. The membrane was also tested in realistic conditions through filtration of alumina sol synthesized in an extremely acidic H2SO4 solution. The results have shown that 99% recovery of the aluminium sulfate particles is possible with the doped PANI membrane as a result of the hydrophilic, relatively smooth, and antifouling surface created by acid doping. The membrane filtration did not change the size and size distribution of the particles in the sol. After filtration, concentrated particles were converted into powder form in 24 h at room temperature without using a dryer. The method proposed in this study is easy and robust and can be used to develop acid-resistant UF membranes not only for concentrating the alumina sol but also for recovering valuable compounds from acid-containing feeds.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 13
    Development of Agcl-Tio2 Xerogels Entrapped Antibacterial Polyacrylonitrile Membranes: the Effect of High Salinity Water on Silver Release, Antibiofouling and Antibacterial Efficacies
    (Elsevier Ltd., 2020) Uz, Metin; Yaşar Mahlıçlı, Filiz; Şeker, Erol; Alsoy Altınkaya, Sacide
    Silver-containing antibacterial membranes are commonly used to control biofouling during bacteria filtration. Unfortunately, fast and uncontrolled release of silver to water is a challenge since this causes mass accumulation of silver in water resources and insufficient long-term antimicrobial effect. To overcome these disadvantages, we propose to add AgCl-TiO2 xerogels (0–0.8 wt%) in the polyacrylonitrile membranes. The long-term silver retaining of the membranes was evaluated by measuring the silver release under filtration of deionized water in the absence and the presence of 1 M NaCl up to 5 days. The antibiofouling and the antibacterial efficacies were determined by measuring the changes in antibacterial activity and DI water flux of the membranes at the end of 5 days of E. coli filtration. The 0.2 wt% AgCl-TiO2 xerogel incorporated polyacrylonitrile membrane demonstrated a constant ~1 ?g of silver release/cm2 per filtration cycle after a total filtration of 0.05 L/cm2 with 1 M NaCl solution. Additionally, it showed antibacterial efficacy and ~100% recovery of deionized water flux by simple backwashing with water after having been used in many E. coli filtration cycles. Thus, this membrane could potentially be used up to ~5.8 years for 8000 h a year for the filtration of high salinity water. Statement of novelty: Silver-containing antibacterial membranes are commonly used to control biofouling during bacteria filtration. Uncontrolled release of silver from the membrane causes massive silver accumulation in water which in turn leads to contamination of water resources and threat to aquatic organisms. Although silver release is strongly influenced by the salinity of water, the release data was collected through filtration of pure DI water or tap water in literature. To overcome the shortcomings of the published studies, we propose to use AgCl-TiO2 xerogels in membranes due to low solubility of AgCl in water and measure the release by filtering high-salinity water. © 2020 Elsevier B.V.
  • Article
    Citation - WoS: 34
    Citation - Scopus: 35
    Development of High Flux Nanofiltration Membranes Through Single Bilayer Polyethyleneimine/Alginate Deposition
    (Elsevier Ltd., 2019) Tekinalp, Önder; Alsoy Altınkaya, Sacide
    The aim of this study is to prepare high flux, stable, antifouling nanofiltration membranes through single bilayer polyelectrolyte deposition. To this end, a tight ultrafiltration support membrane was prepared from a polysulfone/sulfonated polyethersulfone blend. Deposition of a polyethyleneimine and alginate pair on this support has reduced the molecular weight cut off from 6 kDa to below 1 kDa. The pure water permeability and polyethylene glycol 1000 rejection of the coated membrane were found to be 15.5 ± 0.3 L/m2·h·bar and 90 ± 0.6%, respectively, by setting the deposition pH for each layer to 8 and the ionic strengths to 0.5 M and 0 M. This membrane has exhibited significantly higher permeability than commercial membranes with the same molecular weight cut off, retaining 98% of the initial flux during 15 h filtration of bovine serum albumine. In addition, the membrane has been able to completely remove anionic dyes from aqueous solution by showing 99.9% retentions to Reactive red 141, Brilliant blue G and Congo red with a 2 bar transmembrane pressure. High flux and membrane stability in acidic and salty environments have been achieved when deposition conditions favor high adsorption levels for the first layer and strong ionic cross-linking between the carboxyl group on the alginate and the amine groups on the polyethyleneimine
  • Article
    Citation - WoS: 49
    Citation - Scopus: 55
    A 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, Sacide
    Polyamide-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: 40
    Citation - Scopus: 47
    Gelatin-Based 3d Conduits for Transdifferentiation of Mesenchymal Stem Cells Into Schwann Cell-Like Phenotypes
    (Elsevier Ltd., 2017) Uz, Metin; Büyüköz, Melda; Sharma, Anup D.; Sakaguchi, Donald S.; Alsoy Altınkaya, Sacide; Mallapragada, Surya K.
    In this study, gelatin-based 3D conduits with three different microstructures (nanofibrous, macroporous and ladder-like) were fabricated for the first time via combined molding and thermally induced phase separation (TIPS) technique for peripheral nerve regeneration. The effects of conduit microstructure and mechanical properties on the transdifferentiation of bone marrow-derived mesenchymal stem cells (MSCs) into Schwann cell (SC) like phenotypes were examined to help facilitate neuroregeneration and understand material-cell interfaces. Results indicated that 3D macroporous and ladder-like structures enhanced MSC attachment, proliferation and spreading, creating interconnected cellular networks with large numbers of viable cells compared to nanofibrous and 2D-tissue culture plate counterparts. 3D-ladder-like conduit structure with complex modulus of ∼0.4 × 106 Pa and pore size of ∼150 μm provided the most favorable microenvironment for MSC transdifferentiation leading to ∼85% immunolabeling of all SC markers. On the other hand, the macroporous conduits with complex modulus of ∼4 × 106 Pa and pore size of ∼100 μm showed slightly lower (∼65% for p75, ∼75% for S100 and ∼85% for S100β markers) immunolabeling. Transdifferentiated MSCs within 3D-ladder-like conduits secreted significant amounts (∼2.5 pg/mL NGF and ∼0.7 pg/mL GDNF per cell) of neurotrophic factors, while MSCs in macroporous conduits released slightly lower (∼1.5 pg/mL NGF and 0.7 pg/mL GDNF per cell) levels. PC12 cells displayed enhanced neurite outgrowth in media conditioned by conduits with transdifferentiated MSCs. Overall, conduits with macroporous and ladder-like 3D structures are promising platforms in transdifferentiation of MSCs for neuroregeneration and should be further tested in vivo. Statement of Significance This manuscript focuses on the effect of microstructure and mechanical properties of gelatin-based 3D conduits on the transdifferentiation of mesenchymal stem cells to Schwann cell-like phenotypes. This work builds on our recently accepted manuscript in Acta Biomaterialia focused on multifunctional 2D films, and focuses on 3D microstructured conduits designed to overcome limitations of current strategies to facilitate peripheral nerve regeneration. The comparison between conduits fabricated with nanofibrous, macroporous and ladder-like microstructures showed that the ladder-like conduits showed the most favorable environment for MSC transdifferentiation to Schwann-cell like phenotypes, as seen by both immunolabeling as well as secretion of neurotrophic factors. This work demonstrates the importance of controlling the 3D microstructure to facilitate tissue engineering strategies involving stem cells that can serve as promising approaches for peripheral nerve regeneration.
  • Article
    Citation - WoS: 66
    Citation - Scopus: 73
    Novel 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, Alberto
    A 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.