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Öğe Calix[4]arene derivative bearing imidazole groups as carrier for the transport of palladium by using bulk liquid membrane(ELSEVIER SCIENCE BV, 2012) Akin, Ilker; Erdemir, Serkan; Yilmaz, Mustafa; Ersoz, MustafaThe carrier activity of calix[4]arene containing imidazole groups towards the facilitated transport of palladium(II) through dichloromethane bulk liquid membrane has been studied. The optimum transport conditions were established by the studies on the effect of pH, feed concentration, carrier concentration, receiver phase concentration and transport time. A solution of 1 M hydrochloric acid (HCl) served as receiving phase for maximum transport of the metal ion. Maximum transport efficiency was observed for Pd(II) ion when it was present in the concentration of 10(-3) M and the transport efficiency after 24 h was found as 95%. (C) 2012 Elsevier B.V. All rights reserved.Öğe Enhanced Hydrogen Evolution Catalysis at the Liquid/Liquid Interface by NixSy and NixSy/Carbon Nanotube Catalysts(WILEY-V C H VERLAG GMBH, 2017) Akin, Ilker; Aslan, Emre; Patir, Imren HatayNixSy (NiS and Ni17S18) nanoparticles and their nano-composite with carbon nanotubes (NixSy/CNT) were synthesized by a modified hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy-dispersive X-ray microanalysis. The synthesized materials were used as hydrogen evolution catalysts at the water/1,2-dichloroethane interface by using decamethylferrocene as a lipophilic electron donor. The hydrogen evolution reaction in biphasic systems was investigated by two-phase reactions and by cyclic voltammetry with a four-electrode system. A kinetic study of the hydrogen production was also performed. The rates of the reactions catalyzed by the NixSy nanoparticles and the NixSy/CNT nanocomposite were found to be about 690-fold and 2000-fold higher, respectively, than the rate for the reaction performed in the absence of a catalyst.Öğe Enhanced Hydrogen Evolution Catalysis Based on Cu Nanoparticles Deposited on Carbon Nanotubes at the Liquid/Liquid Interface(WILEY-V C H VERLAG GMBH, 2016) Aslan, Emre; Akin, Ilker; Patir, Imren HatayCopper nanoparticles were electrodeposited in situ on a conductive multi-walled carbon nanotubes (MWCNT) support at a free-standing water/1,2-dichloroethane interface. The Cu/MWCNT nanocomposites act as highly active hydrogen evolution catalysts at the interface in the presence of lipophilic decamethylferrocene as the reducing agent.Öğe Facilitated transport of Cr(VI) through a novel activated composite membrane containing Cyanex 923 as a carrier(ELSEVIER, 2009) Arslan, Gulsin; Tor, Ali; Muslu, Harun; Ozmen, Mustafa; Akin, Ilker; Cengeloglu, Yunus; Ersoz, MustafaThis paper describes the facilitated transport of Cr(VI) through a novel Activated Composite Membrane (ACM) containing Cyanex 923 as a carrier. The ACM was prepared by immobilization of the Cyanex 923 on a polysulfone support by means of interfacial polymerisation. The prepared ACM was characterized by using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques and contact angle measurements. The effect of feed phase composition, carrier concentration of the casting solution and stripping phase composition on the transport of Cr(VI) was investigated. When the feed phase contained 1 X 10(-3) M Cr(VI) at pH 1.0, 99% of Cr(VI) was transported through the ACM (prepared with 3% carrier solution) by using 1 M NaOH as a stripping phase. Furthermore, Cr(VI) was preferably transported in the presence of various metal ions (i.e., Cr(III), Ni(II), Cu(II), Zn(II), Cd(II), Co(II), etc.) and sulphate and nitrate ions had no negative effect on the transport of Cr(VI). The results also showed that transport efficiency of the ACM was reproducible and it could be efficiently used in the long-term separation processes instead of supported liquid membrane (SLM). (C) 2009 Elsevier B.V. All rights reserved.Öğe Green synthesis of reduced graphene oxide/nanopolypyrrole composite: characterization and H2O2 determination in urine(ROYAL SOC CHEMISTRY, 2014) Zor, Erhan; Saglam, Muhammed Esad; Akin, Ilker; Saf, Ahmet Ozgur; Bingol, Haluk; Ersoz, MustafaHere we report on a novel, simple and eco-friendly approach for the fabrication of a reduced Graphene Oxide/nanopolypyrrole (rGO/nPPy) composite material and its electrochemical performance for detection of hydrogen peroxide on a glassy carbon electrode. The characterization of the as-prepared rGO/nPPy composite was investigated by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, scanning electron microscopy, contact angle measurement, cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry, differential pulse voltammetry and chronoamperometry techniques were used to investigate and optimize the performance of the developed electrochemical biosensor. The proposed biosensor showed excellent analytical response towards the quantification of H2O2 at pH 7.40. Under the optimized conditions, the biosensor shows a linear response range from 1.0 x 10(-7) to 4.0 x 10(-6) M concentrations of H2O2. The limit of detection was determined to be 34 nM. Reproducibility, sensitivity, stability and anti-interference capability of the fabricated biosensor for the detection of H2O2 were examined. The biological relevance of the developed electrochemical biosensor was further studied by the determination of H2O2 in urine samples. The real sample analysis of H2O2 was achieved before and after drinking coffee in urine samples. The successful and sensitive determination of H2O2 urine samples indicates that the proposed electrochemical biosensor can be applied to the quantification analysis of H2O2 in real samples.Öğe Green Synthesis of Reduced Graphene Oxide/Polyaniline Composite and Its Application for Salt Rejection by Polysulfone-Based Composite Membranes(AMER CHEMICAL SOC, 2014) Akin, Ilker; Zor, Erhan; Bingol, Haluk; Ersoz, MustafaIn this study, a novel, simple, and eco-friendly enzymatic-reaction-based approach to produce reduced graphene oxide/polyaniline (rGO/PANI) composite material was proposed. Glucose oxidase (GOx) was used as an effective catalyst producing hydrogen peroxide, in the presence of glucose, for the oxidative polymerization of aniline under ambient conditions. The prepared rGO/PANI composite was dispersed in polysulfone (PSf), and the mixed membranes were prepared by the phase inversion polymerization method. The morphology of membranes was investigated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) techniques. The performance of membranes was studied in terms of salt rejection and pure water flux. The incorporation of rGO into the membrane matrix led to hydrophobic membrane surface with the enhanced macro-voids. On the contrary, the contact angle data revealed that the rGO/PANI-incorporated membrane surface is partly hydrophilic due to the PANI fibers in membrane, whereas SEM images showed the enhanced macro-voids. Membranes exhibited an improved salt rejection after rGO/PANI doping. The rGO/PANI-modified membrane loading exhibited a maximum of 82% NaCl rejection at an applied pressure of 10 bar. In addition, the results showed that the PSf-rGO/PANI composite membrane had the highest mean porosity and water flux.Öğe Highly Active Cobalt Sulfide/Carbon Nanotube Catalyst for Hydrogen Evolution at Soft Interfaces(WILEY-V C H VERLAG GMBH, 2016) Aslan, Emre; Akin, Ilker; Patir, Imren HatayHydrogen evolution at polarized liquid-liquid interfaces [water/1,2-dichloroethane (DCE)] by the electron donor decamethylferrocene (DMFc) is catalyzed efficiently by the fabricated cobalt sulfide (CoS) nanoparticles and nanocomposites of CoS nanoparticles formed on multi-walled carbon nanotubes (CoS/CNT). The suspended CoS/CNT nanocomposite catalysts at the interface show a higher catalytic activity for the hydrogen evolution reaction (HER) than the CoS nanoparticles due to the high dispersity and conductivity of the CNT materials, which can serve as the main charge transport pathways for the injection of electrons to attain the catalytic sites of the nanoparticles. The reaction rate increased more than 1000-fold and 300-fold by using CoS/CNT and CoS catalysts, respectively, when compared to a non-catalyzed reaction.Öğe Microwave Assisted Synthesis of Chitosan Nanoparticles(TAYLOR & FRANCIS INC, 2011) Kocak, Nuriye; Sahin, Mustafa; Akin, Ilker; Kus, Mahmut; Yilmaz, MustafaChitosan nanoparticles (CHN) were prepared based on ionotropic gelation between low moleculer weight chitosan and sodium tripolyphosphate (TPP) under microwave irradiation. Particle size, zeta potential, and FT-IR techniques were used for characterization of CHN. The influence of reaction time on the nanoparticle size distribution was investigated, and the results showed that the microwave irradiation method evidently decreases the reaction times and particle size over the conventional method. It was determined by the results of the zeta potential measurements that synthesized CHN under microwave irradiation clearly exhibits more homogeneous and stable dispersion.Öğe A new non-enzymatic sensor based on TiO2-Ag/polypyrrole for electrochemical detection of tyramine(ELSEVIER SCIENCE SA, 2018) Erdogan, Zehra O.; Akin, Ilker; Kucukkolbasi, SemahatThis study presents electrochemical determination of tyramine (TA) using a new electrochemical sensor (TiO2-Ag/PPy/GCE) based on TiO2-Ag/PPy nanocomposite modified glassy carbon electrode (GCE). In addition to SEM, AFM and XRD analysis, the presented sensor was studied with respect to its response to Fe(CN)(6)(4-/3-) and characterized by CV and EIS techniques. Under the optimum conditions, TiO2-Ag/PPy/GCE showed a good linear relationship over a concentration range from 4.10 x 10(-8) to 3.06 x 10(-6) M with a detection limit of 2 x 10(-6) M. The availability of the sensor was examined by analysis of TA in food samples.Öğe Photocatalytic Hydrogen Evolution by Oleic Acid-Capped CdS, CdSe, and CdS0.75Se0.25 Alloy Nanocrystals(WILEY-V C H VERLAG GMBH, 2014) Aslan, Emre; Birinci, Okan; Aljabour, Abdalaziz; Ozel, Faruk; Akin, Ilker; Patir, Imren Hatay; Kus, MahmutPhotocatalytic generation of hydrogen by using oleic acid-capped CdS, CdSe, and CdS0.75Se0.25 alloy nanocrystals (quantum dots) has been investigated under visible-light irradiation by employing Na2S and Na2SO3 as hole scavengers. Highly photostable CdS0.75Se0.25 alloy nanocrystals gave the highest hydrogen evolution rate (1466 mu molh(-1) g(-1)), which was about three times higher than that of CdS and seven times higher than that of CdSe.Öğe Preparation and characterization of novel polysulfone-red mud composite capsules for the removal of fluoride from aqueous solutions(ROYAL SOC CHEMISTRY, 2016) Kazak, Omer; Tor, Ali; Akin, Ilker; Arslan, GulsinThis study is the first investigation on the encapsulation of red mud by a polysulfone matrix through a phase inversion process to obtain composite capsules for the removal of fluoride from aqueous solutions. This approach facilitates the use of red mud in batch and column sorption techniques because the polysulfone matrix renders efficient aqueous diffusivity. The produced polysulfone-red mud composite capsules (red mud@ PSF capsules) were characterized by using FT-IR, TGA, SEM and BET. The batch sorption experiments showed that the red mud@ PSF capsules prepared with a mass ratio of red mud to polysulfone (1 : 1, g : g) provided maximum removal at equilibrium pH between 3.2 and 4.7. The batch equilibrium was attained within 30 minutes and sorption behavior was governed by pseudo-second-order kinetics together with intra-particle diffusion. Isotherm analyses showed that the Freundlich and Redlich-Peterson isotherm models better represented the sorption data, which was confirmed by the Chi-square (chi(2)) statistical test. The capsules could be reused for at least two sorption-desorption cycles without significant change in their sorption efficiency. Batch and column experiments on a real mineral water sample fortified with fluoride (final concentration 10 mg L-1) showed that the red mud@ PSF capsules could be applied to real water samples to reduce the fluoride concentration below the limit value (1.5 mg L-1) recommended by the World Health Organization (WHO) for drinking water.Öğe Preparation of a novel PSf membrane containing rGO/PTh and its physical properties and membrane performance(ROYAL SOC CHEMISTRY, 2015) Saf, Ahmet Ozgur; Akin, Ilker; Zor, Erhan; Bingol, HalukRecent advances in the fabrication of nanostructures such as graphene-related materials have received a lot of attention in membrane technology for the future of water supplies. Herein, we report the synthesis of a reduced graphene oxide/polythiophene (rGO/PTh) composite material using an in situ enzymatic polymerization reaction, which is an eco-friendly and a simple way to construct a nanocomposite material. Polysulfone (PSf) mixed matrix composite membranes containing rGO and rGO/PTh were prepared via a phase inversion method. The morphology of the membranes was evaluated by various characterization methods, including SEM, AFM, contact angle and porosity measurements. The performance and antifouling properties of the membranes were examined in detail. The PSf-rGO/PTh membrane showed a significant improvement in water flux permeability due to the enhancement of hydrophilicity and porosity. Moreover, the PSf-rGO/PTh membrane exhibited an approximately 10 times higher improved water flux than that of the rGO membrane as the pressure was increased. The fouling resistance ratio (FRR) and antifouling properties of the membranes were tested using two different protein solutions: bovine serum albumin (BSA) and cytochrome c (Ctc). The antifouling and FRR properties of the PSf-rGO/PTh membrane decreased due to not only the interactions between the functional groups on the membrane surface and fouling materials, but also the morphological properties of the membrane.Öğe Preparation of new polysulfone capsules containing Cyanex 272 and their properties for Co(II) removal from aqueous solution(ELSEVIER SCI LTD, 2015) Kazak, Omer; Tor, Ali; Akin, Ilker; Arslan, GulsinIn this study, new polysulfone capsules containing Cyanex 272 (Cyanex 272@PSF capsules) were prepared by phase inversion technique for the sorption of Co(II) from aqueous solution. The characterization of the Cyanex 272@PSF capsules which were performed by using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and thermal gravimetric analysis (TGA) indicated that Cyanex 272 was successfully encapsulated by polysulfone. For the Cyanex 272@PSF capsules having the highest sorption efficiency, the encapsulation efficiency was determined as 7.2%. The batch sorption experiments showed that removal of Co(II) from aqueous solutions occurred through the cation-exchange and chelation mechanisms and maximum removal was achieved at an initial pH of 8.0 (final pH of 5.9). The Cyanex 272@PSF capsules produced with dispersed phase containing 2.0% of Cyanex 272 (by wt.) provided the highest Co(II) removal. The sorption equilibrium time was attained within 120 min. By confirming the non-linear Chi-square (x(2)) statistical test, Langmuir isotherm model was the best fit model. Langmuir sorption capacity (Q(o)) and sorption constant (b) were 2.014 mg/g and 0.281 L/mg, respectively. The regenerated capsules could be used three times with no change in their sorption capacities. Based on the experiments performed at initial pH of 8.0 for other metal ions, including Ni(II), Pb(II) and Cd(II), sorption ability of Cyanex 272@PSF capsules was in the order: Co(II) approximate to Ni(II)>Cd(II)>Pb( II). Consequently, Cyanex 272@PSF capsules have potential for removing Co(II) from aqueous solutions. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Removal of arsenate [As(V)] and arsenite [As(III)] from water by SWHR and BW-30 reverse osmosis(ELSEVIER SCIENCE BV, 2011) Akin, Ilker; Arslan, Gulsin; Tor, Ali; Cengeloglu, Yunus; Ersoz, MustafaThe removal of arsenate [As(V)] and arsenite [As(III)] from water was investigated by using reverse osmosis (RO) technique with SWHR and BW-30 (FILMTEC) membranes. The effect of pH and concentration of the feed water and operating pressure on the rejection of both arsenic species was examined. The experimental results indicated that rejection for both As(V) and As(III) mostly depended on the membrane type, pH of the feed water and operating pressure. For both membranes. As(V) rejection was maximum at pH above 4.0, while As(III) could be effectively removed from water at pH above 9.1. The rejection for both arsenic species increased with increasing operating pressure. The lowest permeate concentration of As(III) and As(V) was obtained when SWHR membrane was used. Finally, a natural (ground) water sample containing 50 mu g/L of As(V) and 12 mu g/L of As(III), respectively was treated by using RO with SWHR membrane. The obtained permeate concentration of total arsenic was compared with WHO and EU standards and permeate fluxes were evaluated by considering the chemical composition of the groundwater sample. (C) 2011 Elsevier B.V. All rights reserved.Öğe Selectively facilitated transport of Zn(II) through a novel polymer inclusion membrane containing Cyanex 272 as a carrier reagent -- 2(IWA PUBLISHING, 2012) Yilmaz, Abdurrahman; Arslan, Gulsin; Tor, Ali; Akin, Ilker; Cengeloglu, Yunus; Ersoz, Mustafa[Abstract not Available]Öğe Sorption and kinetic properties of 2-(biphenyl-4-yl)-2-oxoacetaldehyde oxime towards Zn(II) ion(DESALINATION PUBL, 2013) Alici, Onder; Akin, IlkerThis study contains the synthesis of 2-(biphenyl-4-yl)-2-oxoacetaldehyde oxime (keto oxime) and its sorption studies towards Zn(II) ions in aqueous solution. In batch sorption experiments, the experimental results show that keto oxime is an effective sorbent towards Zn(II) ions. Therefore, the effects of solution pH, sorption time, temperature, and initial metal ion concentration on Zn(II) sorption were investigated. Maximum Zn(II) ions removal was obtained at 65 degrees C, for 75 min and at pH 5.0 for keto oxime and the batch sorption capacity was found as 1.00 mmol/g. The characteristics of the sorption process for Zn(II) ions were evaluated by using the Langmuir and Freundlich adsorption isotherms. Also, thermodynamic parameters, i.e. Delta G, Delta S, and Delta H were calculated for the system.Öğe Surface modification of glass beads with glutaraldehyde: Characterization and their adsorption property for metal ions(ELSEVIER, 2009) Ozmen, Mustafa; Can, Keziban; Akin, Ilker; Arslan, Gulsin; Tor, Ali; Cengeloglu, Yunus; Ersoz, MustafaIn this study, a new material that adsorbs the metal ions was prepared by modification of the glass beads surfaces with glutaraldehyde. First, the glass beads were etched with 4 M NaOH solution. Then, they were reacted with 3-aminopropyl-triethoxysilane (APTES). Finally, silanized glass beads were treated with 25% of glutaraldehyde solution. The characterization studies by using Fourier Transform Infrared Spectroscopy (FT-IR),Thermal Gravimetric Analysis (TGA), elemental analysis and Scanning Electron Microscopy (SEM) indicated that modification of the glass bead surfaces was successfully performed. The adsorption studies exhibited that the modified glass beads could be efficiently used for the removal of the metal cations and anion (chromate ion) from aqueous solutions via chelation and ion-exchange mechanisms. For both Pb(II) and Cr(VI), selected as model ions, the adsorption equilibrium was achieved in 60 min and adsorption of both ions followed the second-order kinetic model. It was found that the sorption data was better represented by the Freundlich isotherm in comparison to the Langmuir and Redlich-Peterson isotherm models. The maximum adsorption capacities for Pb(II) and Cr(VI) were 9.947 and 11.571 mg/g, respectively. The regeneration studies also showed that modified glass beads could be re-used for the adsorption of Pb(II) and Cr(VI) from aqueous solutions over three cycles. (C) 2009 Elsevier B.V. All rights reserved.Öğe Vapor deposition of blanket polymeric nanocoatings on porous substrates for the facile preparation of thin film composite membranes(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Sariipek, Fatma; Akin, Ilker; Arslan, Gulsin; Karaman, MustafaIn this study a thin film composite (TFC) membrane was fabricated using initiated chemical vapor deposition (iCVD) of poly(glycidyl methacrylate-diethylamino ethyl methacrylate) thin films on porous fabric membrane supports. iCVD allowed very high deposition rates (50 nm min(-1)) at low substrate temperatures. SEM analysis confirmed that iCVD forms a defect-free blanket type coating over the support surface. The resultant TFC membrane was used for the selectively facilitated transport of Cr(VI) with a maximum transport amount of 81.25% in aqueous medium. The transport efficiency of the TFC membrane was reproducible and it could be efficiently used in the long-term separation processes. (C) 2016 Elsevier Ltd. All rights reserved.
