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Öğe Arsenic(V) removal from underground water by magnetic nanoparticles synthesized from waste red mud(Elsevier Science Bv, 2012) Akin, Ilker; Arslan, Gulsin; Tor, Ali; Ersoz, Mustafa; Cengeloglu, YunusIn this study waste red mud (bauxite residue) sample obtained from Seydisehir (Konya, Turkey) was evaluated for the synthesis of Fe3O4 nanoparticles (NPs) in ammonia solution that can be used to remove As(V) from both synthetic and natural underground water samples. The synthesized Fe3O4-NPs were characterized by using TEM, VSM, XRD, SAXS,TGA and FT-IR spectroscopy. The Fe3O4-NPs assumed a near-sphere shape with an average size of 9 nm. The results showed that synthesized Fe3O4-NP5 from waste red mud have satisfactory magnetic properties and As(V) sorption capacity, especially at low equilibrium arsenate concentrations. (c) 2012 Elsevier B.V. All rights reserved,Öğe Discriminative sensing of DOPA enantiomers by cyclodextrin anchored graphene nanohybrids(Elsevier Science Bv, 2017) Ates, Salih; Zor, Erhan; Akin, Ilker; Bingol, Haluk; Alpaydin, Sabri; Akgemci, Emine G.Discriminative sensing of chiral species with a convenient and robust system is a challenge in chemistry, pharmaceutics and particularly in biomedical science. Advanced nanohybrid materials for discrimination of these biologically active molecules can be developed by combination of individual obvious advantages of different molecular scaffolds. Herein, we report on the comparison of the performance of cyclodextrin functionalized graphene derivatives (x-CD/rGO, x: alpha-, beta-, gamma-) for discrimination of DOPA enantiomers. Within this respect, electrochemical measurements were conducted and the experimental results were compared to molecular docking method. Thanks to cavity size of g-CD and the unique properties of graphene, rGO/gamma-CD nanohybrid is capable of selective recognition of DOPA enantiomers. Limit of detection (LOD) value and sensitivity were determined as 15.9 mu M and 0.2525 mu A mu M-1 for D- DOPA, and 14.9 mu M and 0.6894 mu A mu M-1 for L-DOPA. (C) 2017 Elsevier B.V. All rights reserved.Öğe Efficient adsorption of lead (II) and copper (II) from aqueous phase using oxidized multiwalled carbon nanotubes/polypyrrole composite(Taylor & Francis Inc, 2018) Nyairo, Wilfrida Nyanduko; Eker, Yasin Ramazan; Kowenje, Chrispin; Akin, Ilker; Bingol, Haluk; Tor, Ali; Ongeri, David MokonoPolypyrrole coated oxidized multiwalled carbon nanotubes (oMWCNT/Ppy) were applied to determine the adsorption characteristics of Pb(II) and Cu(II) from their aqueous solutions. Structural and morphological characterization studies using scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared and Raman spectroscopy showed successful preparation of the oMWCNT/Ppy composite. The influence of pH, contact time, and initial metal ion concentration on the adsorption of Pb(II) and Cu(II) was studied. The adsorption processes fitted well with Langmuir isotherm and pseudo-second-order kinetic models. The maximum adsorption capacities for Pb(II) and Cu(II) were determined as 26.32 and 24.39mg/g, respectively. Desorption studies indicated that the oMWCNT/Ppy composite could be reused for five cycles with minimum loss of its initial adsorption capacity.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 Green preparation of a novel red mud@carbon composite and its application for adsorption of 2,4-dichlorophenoxyacetic acid from aqueous solution(Springer Heidelberg, 2017) Kazak, Omer; Eker, Yasin Ramazan; Akin, Ilker; Bingol, Haluk; Tor, AliThis study reports the eco-friendly preparation of a novel composite material consisting of red mud and carbon spheres, denoted as red mud@C composite, and its application for the removal of 2,4-dichlorophenoxyacetic acid herbicide (2,4-D) from aqueous solution. The preparation route has a green approach because it follows the low-energy consuming one-step hydrothermal process by using starch as a renewable carbon precursor and red mud as a waste from aluminum production industry. Characterization of the red mud@C composite was performed by FT-IR, TGA, SEM, TEM, BET, XRD, and Raman microscopy analyses. The batch adsorption studies revealed that the red mud@C composite has higher 2,4-D adsorption efficiency than those of the red mud and the naked carbon spheres. The maximum removal at initial pH of 3.0 is explained by considering the pKa of 2,4-D and pH of point of zero charge (pH(pzc)) of the composite material. The adsorption equilibrium time was 60 min, which followed the pseudo-second-order kinetic model together with intra-particle diffusion model. The isotherm analysis indicated that Freundlich isotherm model better represented the adsorption data, with isotherm parameters of k [15.849 (mg/g) (mg/L)(-1/n) ] and n (2.985). The prepared composite is reusable at least 5 cycles of adsorption-desorption with no significant decrease in the adsorption capacity.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 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 A novel red mud@sucrose based carbon composite: Preparation, characterization and its adsorption performance toward methylene blue in aqueous solution(Elsevier Sci Ltd, 2017) Kazak, Omer; Eker, Yasin Ramazan; Akin, Ilker; Bingol, Haluk; Tor, AliA novel carbonaceous composite material containing red mud and sucrose based carbon spheres, named as RM@ C composite, has been prepared via one-step hydrothermal carbonization (HTC) process. The prepared RM@ C composite is an environmentally friendly material because it utilized the red mud, a waste emerged from aluminium manufacturing, and sucrose, a renewable carbon precursor, in the one-step HTC process. After characterization of the composite material by XRD, FT-IR, TGA and SEM-EDX techniques, and specific surface area, pore size distribution and pH of zero point of charge (pHzpc) measurements, its batch adsorption performance was examined on the methylene blue in aqueous solution. The effective adsorption was achieved at pH = 11. At pH 11, the adsorption performance of RM@ C was superior to both red mud and naked carbon spheres. Kinetic analysis revealed that adsorption equilibrium is attained in 60 min and it is governed by the pseudo-second-order kinetic model together with intra-particle diffusion model. On the basis of isotherm analysis, Langmuir isotherm model better expressed the experimental data than Freundlich model. The Langmuir adsorption capacity of the composite material toward methylene blue was determined as 76.92 mg/g. The adsorption of methylene blue gradually decreased with increasing the ionic strength of the solution. The RM@ C composite can be reused at least five cycles of adsorption-desorption without significant changes in the adsorption efficiency.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 chitosan microcapsules containing modified graphene oxide and investigation of water treatment performance(Springer Int Publ Ag, 2023) Akin, IlkerOne of the most important principles in the twenty-first century is to provide clean water, and the use and dimensions of advanced technologies in water supply are important. One of the most effective directing methods in water treatment is the adsorption method. Especially in recent years, with the re-evaluation of wastes on the agenda, instead of being left to rot, shellfish are re-evaluated by chemical or biological methods and new products are obtained. Chitin and its main derivative, chitosan, are the main products produced in this way. In order to increase the performance and efficiency of using chitosan in water treatment, it is necessary to mechanically strengthen and functionalize chitosan. In this study, it was aimed to prepare a graphene oxide (GO)-doped chitosan microcapsule modified with Fe3O4 nanoparticle. Chitosan-based microcapsules containing different ratios of GO@Fe3O4 were prepared. GO, GO@Fe3O4 and microcapsules (MC); Characterizations were carried out using methods such as SEM, FTIR, EDX mapping, XPS and TGA, and arsenic adsorption performance was investigated in real water samples. In line with the results obtained, it was observed that it showed a stable and high arsenic adsorption performance of 95%.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 Sorption of phenol from aqueous solution by novel magnetic polysulfone microcapsules containing Cyanex 923(Elsevier, 2012) Ozcan, Senar; Tor, Ali; Aydin, Mehmet Emin; Beduk, Fatma; Akin, IlkerThis paper describes the sorption of phenol from aqueous solution by using novel magnetic polysulfone (PSF) microcapsules containing Fe3O4 nanoparticles and mixture of trialkyl-phosphine oxides (Cyanex 923) (Cyanex 923/Fe3O4@PSF microcapsules). The preparation of the Cyanex 923/Fe3O4@PSF microcapsules was based on the phase-inversion technique. The prepared microcapsules were characterized by using Fourier Transform Infrared Spectroscopy (FT-IR), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX) and Vibrating Sample Magnetometer (VSM). Fe3O4 nanoparticles in the microcapsules provided easier separation via application of external magnetic field. The experiments indicated that phenol could be removed from aqueous solution at a pH range between 3 and 9. The Cyanex 923/Fe3O4@PSF microcapsules prepared with dispersed phase containing 3.35% of Cyanex 923 (by wt.) provided the highest removal. The sorption reached an equilibrium in 120 min and it obeyed the pseudo-second order kinetic model. The non-linear Chi-square (chi(2)) statistical test showed that Langmuir isotherm model better represented the sorption data in comparison to Freundlich and Redlich-Peterson models. The Langmuir sorption capacity (Q(o)) and sorption constant (b) were 0.664 mmol/g and 0.855 L/mmol, respectively. The regenerated microcapsules could be used five times with no change in their sorption capacity and magnetic separability. (C) 2012 Elsevier Ltd. All rights reserved.
