Chemical Engineering / Kimya Mühendisliği

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Language: search.filters.language.enSubject: search.filters.subject.Membrane

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  • Article
    Citation - WoS: 17
    Citation - Scopus: 16
    Development of Cissus Quadrangularis-Loaded Poss-Reinforced Chitosan-Based Bilayer Sponges for Wound Healing Applications: Drug Release and in Vitro Bioactivity
    (American Chemical Society, 2023) Değer Aker, Sibel; Tamburacı, Sedef; Tıhmınlıoğlu, Funda
    Nowadays, antibiotic-loaded biomaterials have been widelyusedin wound healing applications. However, the use of natural extractshas come into prominence as an alternative to these antimicrobialagents in the recent period. Among natural sources, Cissus quadrangularis (CQ) herbal extract is usedfor treatment of bone and skin diseases in ayurvedic medicine dueto its antibacterial and anti-inflammatory effects. In this study,chitosan-based bilayer wound dressings were fabricated with electrospinningand freeze-drying techniques. CQ extract-loaded chitosan nanofiberswere coated on chitosan/POSS nanocomposite sponges using an electrospinningmethod. The bilayer sponge is designed to treat exudate wounds whilemimicking the layered structure of skin tissue. Bilayer wound dressingswere investigated with regard to the morphology and physical and mechanicalproperties. In addition, CQ release from bilayer wound dressings and in vitro bioactivity studies were performed to determinethe effect of POSS nanoparticles and CQ extract loading on NIH/3T3and HS2 cells. The morphology of nanofibers was investigated withSEM analysis. Physical characteristics of bilayer wound dressingswere determined with FT-IR analysis, swelling study, open porositydetermination, and mechanical test. The antimicrobial activity ofCQ extract released from bilayer sponges was investigated with a discdiffusion method. Bilayer wound dressings' in vitro bioactivity was examined using cytotoxicity determination, woundhealing assay, proliferation, and the secretion of biomarkers forskin tissue regeneration. The nanofiber layer diameter was obtainedin the range of 77.9-97.4 nm. The water vapor permeabilityof the bilayer dressing was obtained as 4021 to 4609 g/m(2)day, as it is in the ideal range for wound repair. The release ofthe CQ extract over 4 days reached 78-80% cumulative release.The release media were found to be antibacterial against Gram-negativeand Gram-positive bacteria. In vitro studies showedthat both CQ extract and POSS incorporation induced cell proliferationas well as wound healing activity and collagen deposition. As a result,CQ-loaded bilayer CHI-POSS nanocomposites were found as a potentialcandidate for wound healing applications.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 2
    A New-Generation Poly (ether Imide Sulfone) Based Solvent Resistant Ultrafiltration Membrane for a Sustainable Production of Silica Nanopowder
    (Elsevier, 2023) Güngörmüş, Elif; Alsoy Altınkaya, Sacide
    The work presented here demonstrated the feasibility of using a membrane to improve the sustainability of silica nanopowder production. Due to superior chemical resistance, high thermal-oxidative stability, and good processability, poly (ether imide sulfone) has been used for membrane production and modified with amine-functionalized TiO2 nanoparticles. The membrane demonstrated good long-term leaching stability in 40% ethanol and silica synthesis solution and maintained its permeability and rejection characteristics under static and dynamic conditions. Additionally, the high antifouling property of the membrane allowed recovering 99.5% of the nanoparticles. Backwashing with water resulted in a high flux recovery ratio (>93%), and gravity-settling without energy can easily separate silica nanoparticles and water in the backwashing solution. Compared to classical freeze-drying and oven-drying methods, integrating membrane into silica nanopowder production can reduce energy consumption by a factor of 81 and 53. At the same time, the utility cost can be saved by 80% and 69%. Additionally, the solvent and catalyst recovered in the permeate stream can be reused in the synthesis, reducing disposal and purchasing costs. In conclusion, membrane-assisted nanopowder production can minimize the adverse effects caused by commonly used conventional drying methods and make the process more sustainable and environmentally friendly.
  • Article
    Citation - WoS: 16
    Citation - Scopus: 15
    Ultrasound-Assisted Dopamine Polymerization: Rapid and Oxidizing Agent-Free Polydopamine Coatings on Membrane Surfaces
    (Royal Society of Chemistry, 2021) Cihanoğlu, Aydın; Schiffman, Jessica D.; Alsoy Altınkaya, Sacide
    Herein, we report a controllable pathway to accelerate the polymerization kinetics of dopamine using ultrasound as a trigger. The use of ultrasound was demonstrated to dramatically accelerate the slow liquid phase reaction kinetics and increase the deposition rate of the polydopamine coating on the surface of polymeric membranes.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Flat sheet metakaolin ceramic membrane for water desalination via direct contact membrane distillation
    (IWA Publishing, 2022) Zewdie, Tsegahun Mekonnen; Habtu, Nigus Gabbiye; Dutta, Abhishek; Van der Bruggen, Bart
    Hydrophobic metakaolin-based flat sheet membrane was developed via phase inversion and sintering technique and modified through 1H,1H,2H,2H-perfluorooctyltriethoxysilane grafting agents. The prepared membrane was characterized by different techniques such as XRD, FTIR, SEM, contact angle, porosity, and mechanical strength. Their results indicated that the wettability, structural, and mechanical properties of the prepared membrane confirm the suitability of the material for membrane distillation (MD) application. The prepared metakaolin-based flat sheet membrane acquired hydrophobic properties after surface modification with the water contact angle values of 113.2° to 143.3°. Afterward, the membrane performance was tested for different sodium chloride aqueous solutions (synthetic seawater) and various operating parameters (feed temperature, feed flow rate) using direct contact membrane distillation (DCMD). Based on the findings, the prepared membrane at metakaolin loading of 45 wt.% and sintered at 1,300 °C was achieved the best performance with >95% salt rejection and permeate flux of 6.58 + 0.3 L/m2 · h at feed temperature of 80 °C, feed concentration of 35 g/L, and feed flow rate of 60 L/h. It can be con-cluded that further optimization of membrane porosity, mechanical, and surface properties is required to maximize the permeate flux and salt rejection.
  • Article
    Citation - WoS: 11
    Citation - Scopus: 12
    Numerical Modelling Assisted Design of a Compact Ultrafiltration (uf) Flat Sheet Membrane Module
    (MDPI, 2021) Bopape, Mokgadi F.; Van Geel, Tim; Dutta, Abhishek; Van der Bruggen, Bart; Onyango, Maurice Stephen
    The increasing adoption of ultra-low pressure (ULP) membrane systems for drinking water treatment in small rural communities is currently hindered by a limited number of studies on module design. Detailed knowledge on both intrinsic membrane transport properties and fluid hydrodynamics within the module is essential in understanding ULP performance prediction, mass transfer analysis for scaling-up between lab-scale and industrial scale research. In comparison to hollow fiber membranes, flat sheet membranes present certain advantages such as simple manufacture, sheet replacement for cleaning, moderate packing density and low to moderate energy usage. In the present case study, a numerical model using computational fluid dynamics (CFD) of a novel custom flat sheet membrane module has been designed in 3D to predict fluid flow conditions. The permeate flux through the membrane decreased with an increase in spacer curviness from 2.81 L/m(2)h for no (0%) curviness to 2.73 L/m(2)h for full (100%) curviness. A parametric analysis on configuration variables was carried out to determine the optimum design variables and no significant influence of spacer inflow or outflow thickness on the fluid flow were observed. The numerical model provides the necessary information on the role of geometrical and operating parameters for fabricating a module prototype where access to technical expertise is limited.
  • 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: 69
    Citation - Scopus: 77
    Novel Zein-Based Multilayer Wound Dressing Membranes With Controlled Release of Gentamicin
    (John Wiley and Sons Inc., 2019) Kimna, Ceren; Tamburacı, Sedef; Tıhmınlıoğlu, Funda
    Recently, functional multilayer scaffolds with controlled drug release ability come into prominence for wound healing applications to mimic the layered structure of skin tissue and prevent the possible infections at the defect site. In this study, controlled antibiotic releasing zein bilayer membranes were fabricated for treatment of acute skin infections. Gentamicin loaded fibers were prepared by electrospinning on the membrane surface. Membranes were characterized with scanning electron microscope, atomic force microscopy, Fourier transform infrared spectroscopy, contact angle, mechanical analysis, swelling, degradation, and water vapor permeability studies. In vitro cytotoxicity, cell attachment, and proliferation were investigated. Cell attachment on fiber layer was observed with fluorescence imaging. Fabricated fibers showed structural similarity to the skin tissue layers with a fiber diameter range of 350-425 nm and film thickness in the range of 311-361 mu m. Mechanical properties were found compatible with the skin tissue. In addition, membranes showed antimicrobial activity against Staphylococcus aureus and Escherichia coli. The sustained release was achieved with a cumulative release of 94%. Membranes did not show any cytotoxic effect. NIH/3T3 and HS2 cell lines were proliferated on each layer mimicking the multilayer skin tissue. Hence, zein-based bilayer membrane showed promising properties to be used as a potential antimicrobial wound dressing for skin tissue regeneration. (c) 2018 Wiley Periodicals, Inc.
  • Article
    Citation - WoS: 4
    Citation - Scopus: 3
    Modification of Surface Charge Characteristics for Unsupported Nanostructured Titania-Zirconia Uf/Nf Membrane Top Layers With Calcination Temperature
    (Springer, 2020) Erdem, İlker; Çiftçioğlu, Muhsin
    Ceramic membranes are more advantageous alternatives especially for harsh working conditions when compared with the polymeric membranes. The porous multilayer structure of the ceramic membranes (composed of support, intermediate, and top layers) can be prepared via different oxides. Titania and zirconia, having superior properties, are mainly preferred for the top layer formation. The separation properties of the membrane are both dependent on pore morphology and surface charge of the oxide(s) forming the top layer. The effect of surface charge in separation may be very significant in case of filtration of charged species with relatively lower mass as in the ultrafiltration (UF) and nanofiltration (NF). In this study, unsupported membrane top layers were prepared with varying titania/zirconia ratios by sol-gel technique. Their surface charges at different pH conditions after calcination at varying temperatures (400 degrees, 500 degrees, and 600 degrees C) were determined. The surface charge of the pure titania (full Ti) top layer was decreasing with the increasing calcination temperature. The highest magnitudes of zeta potential for both acidic and basic conditions were measured via Zr rich top layer (TiZr2575) at calcination temperatures >= 500 degrees C, which was composed of anatase, rutile (titania), and tetragonal (zirconia) phases after calcination. The tailor-made top layer can be prepared with modifications during membrane preparation.
  • Article
    Citation - Scopus: 2
    The Surface Charge of Unsupported Nano-Structured Titania Ceramic Membrane Top Layers With Varying Calcination Temperatures
    (University of Chemical Technology and Metallurgy, 2019) Erdem, İlker; Çiftçioğlu, Muhsin
    Titania is one of the most preferable ceramic membrane materials of superior durability (as zirconia) when compared to that of other ceramics, e.g. alumina or silica. The surface charge of the membrane top layer is an important parameter of the separation performance of the multilayer ceramic membrane due to the Donnan exclusion mechanisms. In this study, the change of the surface charge of unsupported nano-structured titania top layer is investigated with calcination temperature variation. The effect observed indicates the possibility of preparation of tailor-made top layers for multilayer ceramic membranes. © 2019, University of Chemical Technology and Metallurgy.
  • 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.