Browsing by Author "Ozay, Ozgur"

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4-Vinylpyridine Smart Nanoparticles With N-Isopropylacrylamide, 2-Hydroxyethyl Methacrylate, Acrylic Acid, and Methacrylic Acid for Potential Biomedical Applications
(Bentham Science Publ Ltd, 2011) Sahiner, Nurettin; Ozay, Ozgur; Aktas, Nahit
Stimuli-responsive (pH, temperature and magnetic field) 4-vinylpyridine (4-VP)-based nanoparticles in copolymeric formulation with core-shell morphology were synthesized using N-isopropylacrylamide (NIPAM), 2-hydroxyethyl methacrylate (HEMA), acrylic acid (AAc), and methacrylic acid (MAc) as shell-forming monomers. Keeping the 4-VP ratio constant and varying the comonomer amounts produced particles with variant shell thickness. Multi-responsive p(4-VP)-based nanoparticles were further modified by reacting with different functional groups containing bromoalkanes by quaternization. These p(4-VP)-based particles were also utilized to include composite materials by encapsulating separately prepared magnetic ferrites. To demonstrate the potential usage of the synthesized particles and their modified forms as drug delivery devices, naproxene sodium salt as an antibacterial drug was used for in vitro release studies in PBS.
Adsorption of Malachite Green From Aqueous Solution Using Hydroxyethyl Starch Hydrogel Improved by Graphene Oxide
(Springer, 2022) Onder, Alper; Kivanc, Mehmet Riza; Durmus, Secil; Ilgin, Pinar; Ozay, Hava; Ozay, Ozgur
This study is the first report of the preparation of hydroxyethyl starch (HES) hydrogels rapidly crosslinked with divinyl sulfone in a single step and single pot. To develop the physical and chemical features of hydrogels, Graphene oxide (GO) nanoparticles were combined with the crosslinked HES. In addition to swelling studies, structural characterization of the samples was conducted with a scanning electron microscope (SEM) and transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis and thermogravimetric analysis (TGA). For the removal of malachite green model dye by GO-HES, the effects of GO content, solution concentration, temperature, contact duration, dosage and pH on varying adsorption features were researched. Additionally, adsorption isotherms, kinetic and thermodynamic systematics were analyzed. The maximum adsorption capacity of GO-HES composite hydrogel was found to be 89.3 mg/g for Langmuir isotherm. The possible adsorption mechanism of the composite hydrogels for malachite green dye involved electrostatic, hydrogen bonding, and pi-pi interactions. In addition to reasonable cost and simple synthesis method, the prepared composite materials have potential use in wastewater treatment as adsorbents for the removal of dye from aqueous solutions due to efficient adsorption capacity.
Adsorption of Methylene Blue From Aqueous Solution Using Poly(2-Acrylamido Acid-Co Methacrylate) Hydrogel Crosslinked by Activated Carbon
(Taylor & Francis inc, 2023) Ilgin, Pinar; Onder, Alper; Kivanc, Mehmet Riza; Ozay, Hava; Ozay, Ozgur
This study aimed to develop an environmentally friendly, inexpensive, and efficient adsorbent for removing methylene blue (MB) dye from wastewater using a three-dimensional porous poly(2-Acrylamido-2-methyl-1-propanesulfonic acid-co-2-Hydroxyethyl Methacrylate), p(AMPS-co-HEMA) composite hydrogel crosslinked with vinyl-functionalized activated carbon (VAC). The surface morphology and chemical structure of the crosslinker were characterized using transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area analysis, X-ray spectroscopy (XRD) and Fourier transform-infrared spectroscopy (FT-IR) instruments. The surface morphology, chemical structure and thermal properties of the hydrogel were also characterized using scanning electron microscopy (SEM), FT-IR and thermogravimetric analyzers (TGA). Experimental parameters affecting the adsorption behavior, such as initial dye concentration, time, dosage, pH, and temperature, were systematically investigated. Hydrogel achieved optimal MB removal efficiency (69.53%) at an initial MB concentration of 250 mg/L (1 mg/mL, pH not adjusted) over 24 h. Adsorption kinetics, isotherm, thermodynamic studies, and reusability were investigated. Experimental adsorption isotherm and kinetic data followed the Langmuir model and pseudo-second-order kinetics with a maximum adsorption capacity of 284.90 mg/g hydrogel at 293 K. Thermodynamic findings proved the spontaneity and endothermic behavior of the adsorption process. After 5 adsorption-desorption cycles, the adsorption capacity of the composite hydrogel decreased by only 7.51 mg/g compared to the initial adsorption capacity.
Aromatic Organic Contaminant Removal From an Aqueous Environment by P(4-Vp) Materials
(Pergamon-elsevier Science Ltd, 2011) Sahiner, Nurettin; Ozay, Ozgur; Aktas, Nahit
p(4-vinylpyridine) (p(4-VP)) hydrogels were prepared in bulk (macro, 5 x 6 mm) and in nanosizes (370 nm) dimensions. The prepared hydrogels were used to remove organic aromatic contaminates such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP), phenol (Ph) and nitrobenzene (NB) from an aqueous environment. Important parameters affecting the absorption phenomena, such as the initial concentration of the organic species and the absorbent, absorption rate, absorption capacity, pH and the temperature of the medium, were evaluated for both hydrogel sizes. The absorption capacity of bulk and microgels were found to be 4-NP > 2-NP > Ph > NB. Furthermore, p(4-VP) microgels were embedded in poly(acrylamide) (p(AAm)) bulk hydrogel as a microgel-hydrogel interpenetrating polymer network and proved to be very practical in overcoming the difficulty of using the microgels in real applications. Moreover, it was demonstrated that separately prepared magnetic ferrite particles inserted inside p(4-VP) microgels during synthesis allowed for trouble-free removal of p(4-VP)-magnetic composite microgels from the aqueous environment by an externally applied magnetic field upon completion of their task. (C) 2011 Elsevier Ltd. All rights reserved.
Arsenic (V) Removal With Modifiable Bulk and Nano P(4-Vinylpyridine) Hydrogels: the Effect of Hydrogel Sizes and Quarternization Agents
(Elsevier, 2011) Sahiner, Nurettin; Ozay, Ozgur; Aktas, Nahit; Blake, Diane A.; John, Vijay T.
Macrogels and nanogels (5 x 6 mm and 370 nm dimensions, respectively) based on 4-vinylpyridine (p-(4VP)) were prepared using redox and microemulsion techniques. The p(4-VP)-based materials were quaternized with HCl/alkyhalides having different chain lengths to tune the charges (macro and nanogels) and size of nanogels. By developing positive charge on the p(4-VP) materials, they behaved as ion exchangers and used in removal of As(V) from aqueous environments. The prepared p(4-VP) materials were also rendered responsive to magnetic field by in situ incorporation of magnetic metal nanoparticles inside macro p(4-VP) hydrogels and by encapsulation of separately prepared magnetic ferrites by nanosized p(4-VP) particles. Nanoparticles quaternized with HCl (p(4-VP)-HCl) (1 g) removed over 95% of As(V) from a stock solution (10 mg L-1 1000 mL) in 15 min whereas bulk hydrogels removed >82% of the As(V) from an equivalent solution in similar to 12 h. Parameters effecting the As(V) removal, including pH, temperature and ionic strength, were also investigated. The synthesized magnetic p(4-VP) composites could be reused after elution with NaOH and regeneration with quaternization agents; these procedures were facilitated using an externally applied magnetic field. The Langmuir and Freundlich adsorption isotherms were also applied to study the removal of As(V) from aqueous environments. (C) 2011 Elsevier B.V. All rights reserved.
Coll 490-Colloidal P(4-Vp) Particles and Composites for Biomedical Application
(Amer Chemical Soc, 2009) Ozay, Ozgur; Aktas, Nahit; Dulger, Basaran; Silan, Coskun; John, Vijay T.; Sahiner, Nurettin
Controllable Hydrogen Generation by Use Smart Hydrogel Reactor Containing Ru Nano Catalyst and Magnetic Iron Nanoparticles
(Elsevier, 2011) Sahiner, Nurettin; Ozay, Ozgur; Inger, Erk; Aktas, Nahit
In this study, p(AMPS) hydrogels are synthesized from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) via a photo polymerization technique. The hydrogels are used as template for metal nanoparticles and magnetic ferrite nanoparticles. and also as a catalysis vessel in the generation of hydrogen from the hydrolysis of NaBH4. Approximately 5 nm Ru (0) and 20-30 nm magnetic ferrite particles are generated in situ inside this p(AMPS) hydrogel network and then used as a catalysis medium in hydrogen production by hydrolysis of sodium boron hydride in a basic medium. With an applied external magnetic field, the hydrogel reactor, containing Ru and ferrite magnetic particles, can be removed from the catalysis medium; providing on-demand generation of hydrogen. The effect of various parameters such as the initial concentration of NaBH4. the amount of catalyst and temperature on the hydrolysis reaction is evaluated. The activation energy for hydrogen production by Ru (0) nanoparticles is found to be 27.5 kJ mol(-1); while the activation enthalpy is 30.4 kJ mol(-1). The hydrogen generation rate in presence of 5 wt% NaOH and 50 mg p(AMPS)-Ru catalyst is 8.2 L H-2 min(-1) g Ru. (C) 2011 Elsevier B.V. All rights reserved.
Hydrogel Assisted Nickel Nanoparticle Synthesis and Their Use in Hydrogen Production From Sodium Boron Hydride
(Pergamon-elsevier Science Ltd, 2011) Ozay, Ozgur; Aktas, Nahit; Inger, Erk; Sahiner, Nurettin
In this study, hydrogels were synthesized from 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) via a photo polymerization technique. Approximately 100 nm Ni metal nanoparticles were generated in situ inside these p(AMPS) hydrogel networks and used as a catalyst in hydrogen production by hydrolysis of sodium boron hydride in a basic medium. The effects of several parameters on the hydrolysis reaction such as the amount of catalyst, the initial concentration of NaBH4, and the temperature were investigated. The activation energy, activation enthalpy and activation of entropy for the reaction were calculated as 42.28 kJ mol(-1), 39.59 kJ mol(-1) and -171.67 J mol(-1) K-1, respectively. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.
Hydrogels as a Potential Chromatographic System: Absorption, Speciation, and Separation of Chromium Species From Aqueous Media
(Taylor & Francis inc, 2011) Ozay, Ozgur; Aktas, Nahit; Sahiner, Nurettin
Hydrogels with highly charged forms and amphiphilic character, based on an anionic monomer 2-acrylamido-2-methyl-1-propansulfonic acid sodium salt (AMPSNa) and a cationic monomer 3-acrylamidopropyltrimethylammoniumchloride (APTMACl), were synthesized via a photo-polymerization technique and investigated for potential use in the separation of chromium species with different oxidation states. They were used for three main purposes. First, a single chromium species was successfully removed from an aqueous medium in the presence of other forms using the appropriate design and synthesis of the hydrogels. Secondly, the copolymerized p(AMPSNa-co-APTMACl) hydrogels were used to remove two chromium species simultaneously from an aqueous medium. Lastly, in addition to speciation of the chromium species, their separation and removal by an externally applied magnetic field using magnetically responsive hydrogels was demonstrated.
Hydrogen Production From Ammonia Borane Via Hydrogel Template Synthesized Cu, Ni, Co Composites
(Pergamon-elsevier Science Ltd, 2011) Ozay, Ozgur; Inger, Erk; Aktas, Nahit; Sahiner, Nurettin
In situ Co, Cu and Ni nanoparticles were synthesized by chemical reduction of the absorbed Co (II), Cu (II) and Ni (II) ions inside hydrogel networks prepared from 2-acryl-amido-2-methyl-1-propansulfonic acid (AMPS) and were used as a catalyst system in the generation of hydrogen in hydrolysis of ammonia borane (AB). Several parameters affecting the hydrolysis reaction such as the type of the metal, the amount of catalyst, the initial concentration of AB, and temperature, were investigated. The activation energy values in the hydrolysis reaction of AB solution in the presence p(AMPS)-Co, p(AMPS)-Cu and p(AMPS)-Ni catalyst systems were calculated as E-a = 47.7 kJ mol(-1), 48.8 kJ mol(-1) and 52.8 kJ mol(-1), respectively. Thus, the catalytic activity of the metal nanoparticles prepared inside the same hydrogel matrix was found to be Ni < Cu < Co. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
In Situ Preparation of Various Metal Nanoparticles Within Hydrogel Networks and Their Application in Catalysis
(Amer Chemical Soc, 2011) Sahiner, Nurettin; Ozay, Ozgur; Butun, Sultan; Demir, Veil; Dibek, Burak; Aktas, Nahit; John, Vijay T.
Magnetic Hydrogel Syntheses and Their Applications in the Environment for the Removal of Toxic Metal Ions
(Amer Chemical Soc, 2009) Ozay, Ozgur; Onder, Alper; Sahan, Tekin; Aktas, Nahit; Baran, Yakup; John, Vijay T.; Sahiner, Nurettin
New Catalytic Route: Hydrogels as Templates and Reactors for in Situ Ni Nanoparticle Synthesis and Usage in the Reduction of 2-And 4-Nitrophenols
(Elsevier Science Bv, 2010) Sahiner, Nurettin; Ozay, Hava; Ozay, Ozgur; Aktas, Nahit
Nickel nanoparticles inside poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS)) hydrogel were prepared by reduction of Ni(II) ions absorbed within hydrogel network. TEM images confirmed that in situ formed nickel particle in p(AMPS) hydrogel networks are about 100 nm. These nickel metal nanoparticles containing hydrogel-composites were utilized as catalysts and reaction media for the reduction reactions of aromatic nitro compounds, 2- and 4-nitrophenols with aqueous NaBH(4). The reduction rate constants at four different temperatures (30, 40,50 and 60 degrees C) and activation parameters were calculated. The activation energies (E(a)) for 4- and 2-nitrophenols are 25.70 and 38.69 kJ mol(-1), respectively. It was found that these types of hydrogel-composite catalyst systems can be used repetitively up to five times with 100% conversion and only with 25% reduction in the initial reduction rate. (c) 2010 Elsevier B.V. All rights reserved.
Novel Stimuli-Responsive Hydrogels Derived From Morpholine: Synthesis, Characterization and Absorption Uptake of Textile Azo Dye
(Springer, 2017) Ilgin, Pinar; Ozay, Ozgur
A new cationic monomer methacrylamido-4-(2-aminoethyl) morpholine, (MAEM) derived from morpholine was synthesized in a single step and characterized by FTIR, H-1 and C-13 NMR analyses. Through free radical aqueous polymerization, novel copolymeric hydrogels have been prepared successfully using methacrylamido-4-(2-aminoethyl) morpholine and acrylamide (Aam) as monomers. Later on SEM, FTIR, elemental analysis and TG instruments were used to characterize the obtained poly(acrylamide-co-methacrylamido-4-(2-aminoethyl) morpholine), poly(Aam-c-MAEM), hydrogels. Poly(Aam-c-MAEM) hydrogels were tested for swelling, diffusion and uptake of reactive orange, RO, anionic dye. In this regard, various adsorption kinetics and isotherm models as well as operation parameters were systematically examined and discussed in detail in relation to adsorption uptake such as pH of media, comonomer composition, adsorbent dosage, temperature, initial dye concentration and contact time. The description of adsorption process of RO on hydrogels was consistent with the pseudo-second-order model followed by Elovich and pseudo-first-order. The best fitting adsorption model was selected on the basis of R-2, in the order of: Temkin > D-R > Langmuir > Freundlich isotherm. The results obtained in this study demonstrate that poly(Aam-c-MAEM) hydrogels provide an excellent advantage for application of this hydrogel system in the removal of anionic textile dyes from wastewater.
The on Demand Generation of Hydrogen From Co-Ni Bimetallic Nano Catalyst Prepared by Dual Use of Hydrogel: as Template and as Reactor
(Pergamon-elsevier Science Ltd, 2011) Sahiner, Nurettin; Ozay, Ozgur; Aktas, Nahit; Inger, Erk; He, Jibao
We report the preparation of metal nanoparticles in various formulations inside p(2-acrylamido-2-methyl-1-propansulfonic acid; p(AMPS)) hydrogels and their utilization as a catalyst in hydrolysis of NaBH4. The swollen, flexible p(AMPS) network was used for metal ion loading and reduction in situ for the preparation of Co:Ni nanoparticles as bimetallic clusters in various formulation, and Co and Ni bimetallic catalysts as Co + Co, Co + Ni, Ni + Co and Ni + Ni. In addition to utilization of hydrogels as support materials, the p(AMPS)-metal nanoparticle system was used as catalyst to generate hydrogen in the hydrolysis of NaBH4 with very high yield. Various parameters for the hydrolysis reaction were determined and the activation parameters were calculated. For the first time, inclusion of ferrite magnetic particles to control hydrogen generation on demand by using an externally applied magnetic field to remove the hydrogel-catalyst system from the hydrolysis medium is reported. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
P(4-Vinyl Pyridine) Hydrogel Use for the Removal of Uo22+ and Th4+ From Aqueous Environments
(Academic Press Ltd- Elsevier Science Ltd, 2011) Ozay, Ozgur; Ekici, Sema; Aktas, Nahit; Sahiner, Nurettin
4-vinyl pyridine (4-VP) based hydrogels with 2-hydroxyethylmetacrylate (HEMA) and magnetic composites were prepared and tested for use in the removal of UO22+. and Th4+ ions from aqueous environments. It was found that the absorption of these metal ions from aqueous environments decreased with an increase in the amount of HEMA contained within p(4-VP-co-HEMA) hydrogels between 0.498 mmol for pure p(4-VP) and 0.027 mmol for pure p(HEMA). The characterization of the hydrogels was determined by swelling experiments, FT-IR and thermal analysis. The effects of initial metal ion concentration, hydrogel amount and the temperature of the medium on absorption of the ions were investigated. Langmuir and Freundlich isotherms were constructed for the absorption of UO22+ and Th4+. Both isotherms demonstrated that these metal ions complied with monolayer absorption kinetics. (C) 2011 Elsevier Ltd. All rights reserved.
P(4-Vp) Based Nanoparticles and Composites With Dual Action as Antimicrobial Materials
(Elsevier Science Bv, 2010) Ozay, Ozgur; Akcali, Alper; Otkun, Mueserref Tatman; Silan, Coskun; Aktas, Nahit; Sahiner, Nurettin
Polymeric 4-VP (p(4-VP)) particles were synthesized in an oil-in-water microemulsion system using various amounts of ethylene glycol dimethacrylate (EGDMA) as crosslinker. The prepared p(4-VP) particles were chemically modified to obtain positively charged particles as polyelectrolytes. Furthermore, these p(4-VP) particles were used for in situ Ag and Cu metal nanoparticle syntheses to provide dual action with an additional advantage as bactericidal particles. The synthesized p(4-VP) particles with positive charges and metal constituents were tested for potential antibacterial action against various bacteria such as Staphylococcus aureus ATCC6538, Pseduomonas aeruginosa ATCC9027, Bacillus subtilis ATCC6633, Escherichia coli ATCC8739. It was found that p(4-VP) particles, especially the positively charged forms had potential as antibacterial materials. The synthesized particle dimensions were characterized with TEM, and DLS measurements. Chemical modification of the particles was confirmed by FT-IR spectroscopy and zeta potential measurements, and the metal nanoparticle contents were determined with thermogravimetric (TGA) studies. (C) 2010 Elsevier B.V. All rights reserved.
Removal of Anionic Dyes From Aqueous Media by Using a Novel High Positively Charged Hydrogel With High Capacity
(Taylor & Francis inc, 2022) Kivanc, Mehmet Riza; Ozay, Ozgur; Ozay, Hava; Ilgin, Pinar
Poly((methacryloylamino)propyl trimethylammonium chloride-co-vinylimidazole) (p(MAPTAC-co-VI)) hydrogels were synthesized through free radical polymerization of 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC) and 1-vinylimidazole (VI) in aqueous solutions with ammonium persulfate (APS) used as initiator and N,N '-methylenebis(acrylamide) (MBA) as the crosslinking agent. By modifying with HCl, the positive charge density on the hydrogel network structure was increased and quaternized hydrogels (p(MAPTAC-co-VI)-q) were obtained. Traditional swelling and spectrophotometric characterization techniques were used to gain a better understanding of the performance of cationic hydrogels for the removal of anionic dyes. FTIR, SEM, and EDX confirmed the structure of the hydrogel before and after the adsorption process. Later, dye adsorption performance of these p(MAPTAC-co-VI)-q hydrogels was investigated under different adsorption conditions, including initial concentration, temperature, pH values of dye solutions, and adsorption contact time, adsorbent dosage and in real water samples. Various isotherm and kinetic models of dye adsorption by the hydrogel were also studied and the experimental adsorption followed a pseudo-second order model and fitted the Langmuir isotherm well. Thanks to the effective use of existing adsorption sites, high adsorption capacity was achieved for eriochrome black T (EBT) and methyl orange (MO) dyes. The values of q(max) are as follows: 1818.2 mg/g and 1449.3 mg/g, respectively. Thermodynamic parameters indicate that the process was spontaneous and endothermic. P(MAPTAC-co-VI)-q hydrogels can be used as a potential adsorbent for removal of anionic dye molecules, one of the industrial pollutants, from wastewater.
The Removal of Cyanide Ions From Aquatic Environments by Quaternizable P(4-Vp) Hydrogels of Different Dimensions
(Springer, 2013) Sahiner, Nurettin; Ozay, Ozgur; Aktas, Nahit
Hydrogels based on p(4-VP) of different dimensions were prepared and, after chemical modification, were used in the removal of one of the most potent toxic materials, cyanide. Macro and micron p(4-VP) hydrogel swelling behavior was evaluated in various aquatic environments. HCl, bromoethane, 1-bromobutane, 1-bromohexane, and 2-bromoethylamine were used as quaternizing agents to generate positive charges on both p(4-VP) macrogels and microgels. The modified p(4-VP) macrogels and microgels were used in cyanide ion removal for the first time from aqueous environments. The p(4-VP)-HCl at macro and micro sizes removed almost 49 and 61 mg cyanide ions per gram hydrogel in deionized water after modification, respectively. Moreover, the absorption capacity of the modified p(4-VP) hydrogel did not change significantly in tap, drinking, and creek waters. Parameters that affect the absorption process, such as cyanide concentration, contact time, hydrogel amount, and contaminated water source, were investigated. Additionally, magnetic field responsive macro and micro p(4-VP) hydrogel composites provided many advantages, such as easy handling after cyanide absorption, e. g., ready removal of cyanide-loaded p(4-VP) composites with an externally applied magnetic field. Langmuir and Freundlich adsorption isotherms were applied to the data obtained for cyanide uptake from aqueous environments.
Removal of Toxic Metal Ions With Magnetic Hydrogels
(Pergamon-elsevier Science Ltd, 2009) Ozay, Ozgur; Ekici, Sema; Baran, Yakup; Aktas, Nahit; Sahiner, Nurettin
Hydrogels, based on 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS) were synthesized via photopolymerization technique and used for the preparation of magnetic responsive composite hydrogels. These composite hydrogels with magnetic properties were further utilized for the removal of toxic metal ions such as Cd(II), Co(II), Fe(II), Pb(II), Ni(II), Cu(II) and Cr(III) from aqueous environments. It was revealed that hydrogel networks with magnetic properties can effectively be utilized in the removal of pollutants. The results verified that magnetic iron particle containing p(AMPS) hydrogel networks provide advantageous over conventional techniques. Langmuir and Freundlich adsorption isotherms were applied for toxic metal removal and both isotherms were fit reasonably well for the metal ion absorptions. (c) 2009 Elsevier Ltd. All rights reserved.