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Öğe 0D, 1D, 2D, and 3D Soft and Hard Templates for Catalysis(Elsevier Science Bv, 2017) Bütün, Sultan; Demirci, Şahin; Yaşar, Alper O.; Sağbaş, Selin; Aktaş, Nahit; Şahiner, NurettinCatalytic reactions are generally catalyzed by metal nanoparticles, metal oxides, or their bi- or trimetallic forms with various formulations, morphology, composition, and shapes. The metal nanoparticle catalytic performances are directly related to the surface features of particles such as crystal structure, atomic stacking and order, surface area, roughness and atomic and/or spatial organizations, and the catalyst environments. It's very well-known that the high surface energy of the metal nanoparticles, which is one of the most important challenges to be considered to overcome, leads to aggregation, deactivation, and oxidation problems. Therefore, many templates such as nanoemulsions prepared from surfactant and polymers and nanogels as zero-dimensional (0D) soft templates; cylindrical or tubular natural or synthetic structures derived from again surfactants, polymers, or peptides or self-assembled structures as one-dimensional (1D) templates; graphene oxide, mica, clay, and silicates as two-dimensional (2D) hard templates; and microgel, bulk hydrogel, and cryogels as three-dimensional (3D) soft templates that are used as stabilizing media will be discussed. Regardless of the sizes of templates, various parameters such as morphology, e.g., core-shell, capsules, guiding direction, porosity, and compartmentation features of the templates, have paramount significance on composition, crystallinity, and shape of the resultant nanoparticle to be used as catalyst. Metal nanoparticles, metal oxides, and metal nanoparticles doped with various elements have been extensively investigated due to their unique physical and chemical properties, and even their bi- or trimetallic forms have been under examination due to synergistic potential application of each of the components. The main concern regarding the nanoparticle synthesis is to overcome their agglomeration, due to their high surface area, high energy, and high surface reactivity resulting in strong tendency to aggregate, leading to deactivation and oxidation. There are a variety of methods available in the synthesis of metal nanoparticles to prevent some of these shortcomings with some catalytic performance sacrifices or with some economical infeasibilities. Nevertheless, the key issue with these methods is the control of the particle size and shapes and the morphology and crystallinity. Therefore, a wide range of templates such as nanoemulsions using surfactant and polymers and nanogels as 0D soft templates; cylindrical or tubular natural or synthetic structures derived from again surfactants, polymers, or peptides or self-assembled structures as 1D templates; graphene, mica, clay, and silicates as 2D hard templates; and microgel, bulk hydrogel, and cryogels as 3D soft templates as stabilizing environments and particle compartments will be discussed. In general, polar molecules or polyelectrolytes stabilizers can be used in both controlling the size and preventing the metal nanoparticles from precipitation processes. Water-soluble polymers, including polyelectrolytes, are the commonly employed stabilizing and/or chelating agents in the preparation of metal ultrafine particles.Öğe 4-Vinylpyridine-Based Smart Nanoparticles with N-Isopropylacrylamide, 2-Hydroxyethyl Methacrylate, Acrylic acid, and Methacrylic Acid for Potential Biomedical Applications(Bentham Science Publ Ltd, 2011) Şahiner, Nurettin; Özay, Özgür; Aktaş, NahitStimuli-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.Öğe A soft hydrogel reactor for cobalt nanoparticle preparation and use in the reduction of nitrophenols(Elsevier Science Bv, 2010) Şahiner, Nurettin; Özay, Hava; Özay, Özgür; Aktaş, NahitBulk poly(2-acrylamido-2-methyl-1-propansulfonic acid) (p(AMPS)) hydrogels were prepared by irradiation of an aqueous solution of AMPS in the presence of crosslinker and photoinitiator. These p(AMPS) hydrogel networks were utilized for in situ cobalt nanoparticle synthesis by reduction of metal ions absorbed into the hydrogel network with a reducing agent, i.e., NaBH(4). TEM images confirmed that Co particles are about 100 nm in size. The hydrogel network with embedded Co nanoparticles was utilized as a catalyst in the reduction of 4-nitrophenol (4-NP) and 2-nitrophenol (2-NP) in aqueous media in the presence of an excess amount of NaBH4. The kinetics of the reduction reaction under different reaction conditions was investigated to determine the activation parameters. Activation energies are 27.8 kJ mol(-1) and 39.3 kJ mol(-1) for 4-NP and 2-NP, respectively. It was found that hydrogel-Co composites were 99% active after 5 days storage. (C) 2010 Elsevier B.V. All rights reserved.Öğe Amidoximated poly(acrylonitrile) particles for environmental applications: Removal of heavy metal ions, dyes, and herbicides from water with different sources(Wiley, 2016) Ajmal, Muhammad; Demirci, Şahin; Siddiq, Mohammad; Aktaş, Nahit; Şahiner, NurettinMonodispersed poly(acrylonitrile) [p(AN)] particles were prepared by surfactant free emulsion polymerization and the hydrophobic nitrite groups were converted to hydrophilic amidoxime groups by treatment with hydroxylamine hydrochloride (NH2OH center dot HCl) in water. The p(AN) and amidoximated p(AN) [amid-p(AN)] particles were characterized by Fourier transformation infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The prepared particles were used as adsorbents in the removal from aqueous media of three different types of pollutants; organic dyes methylene blue (MB), and rhodamine 6 G (R6G), a heavy metal ion Cd (II), and a herbicide paraquat (PQ). The effects of various parameters such as amidoximation, pH of solution, amount of particles, and the initial concentration of solution were investigated. Upon amidoximation, a great increase in the adsorption capacity of the prepared particles was observed as the adsorbed amounts were increased to 87, 91, 74, and 91 mg/g from 5, 1.54, 1.06, and 1.22 mg/g for Cd (II), MB, R6G, and PQ, respectively. The amid-p(AN) particles were also able to remove considerable amounts of these pollutants from tap, river, and sea water. Langmuir, Freundlich, and Temkin adsorption isotherms were applied and it was found that the adsorption of Cd (II) and PQ followed the Langmuir adsorption model, whereas the adsorption of MB was found to obey the Freundlich adsorption isotherm. Pseudo first-order and pseudo second-order kinetics were also applied and the results showed that the adsorption processes of Cd (II), PQ, MB, and R6G follow pseudo second-order kinetics. (C) 2015 Wiley Periodicals, Inc.Öğe An alternative to metal catalysts: Poly(4-vinyl pyridine]-based polymeric ionic liquid catalyst for H2 generation from hydrolysis and methanolysis of NaBH4(Pergamon-Elsevier Science Ltd, 2016) Şahiner, Nurettin; Yaşar, Alper O.; Aktaş, NahitMonodispersed p(4-VP) (poly(4-vinyl pyridine)) polymeric particles were synthesized via self-emulsion polymerization and modified with 1,2-dibromobutane 1,4-dibromobutane and 1,6-dibromobutane, to obtain polymeric ionic liquid (PIL) particles of poly(4-vinyl pyridine)-dibromoethane (p(4-VP)C-++(2)), poly(4-vinyl pyridine)-dibromobuthane (p(4-VP)C-++(4)), and poly(4-vinyl pyridine)-dibromohexane (p(4-VP)C-++(6)) particles. Highly mono dispersed p(4-VP), p(4-VP)C-++(2), p(4-VP)C-++(4) and p(4-VP)C-++(6) particles were obtained with the sizes of 335 +/- 10, 451 +/- 17, 432 +/- 13 and 443 +/- 24 nm, and the zeta potential values of 6.3 +/- 0.6, 31.2 +/- 2.1, 33.3 +/- 1.0 and 35.5 +/- 1.1 mV. PIL-metal composites of p(4-VP)C-++(6)-Co p(4-VP)C-++(6)-Ni and p(4-VP)C-++(6)-Fe particles were prepared by reducing CoCl2, NiCl2 and FeC13 metal salts loaded into p(4-VP)C-++(6) microgels and then reducing with NaBH4. The prepared PIL-metal composites and PIL particles were used as catalysts in H-2 generation from the hydrolysis and methanolysis of NaBH4. It was found that the prepared PIL-metal composites (e.g., p(4-VP)C-++(6)-Co) showed better catalytic performances than PIL particles (e.g., p(4-VP)C-++(6)) for the hydrolysis reaction of NaBH4 whereas, PIL catalytic performances were much better than PIL-metal composites for the methanolysis of NaBH4. Various parameters affecting the hydrolysis and methanolysis reactions of NaBH4 such as the types of PIL/PIL-metal particle, the amount of PIL particles, the amount of NaBH4 and temperature were investigated. A very high hydrogen generation rate (HGR) value for the methanolysis reaction of 500 mM NaBH4 catalyzed by 50 mg p(4-VP)C-++(6) at 25 degrees C was calculated as 9125 +/- 177 mL H-2 (g of catalyst min)(-1). Furthermore, very low activation energy (Ea), 13.78 +/- 0.23 kJ morl was calculated for the methanolysis of NaBH4 catalyzed by p(4-VP)C-++(6) at temperatures in the range of 0-40 degrees C. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe An approach for prediction of optimum reaction conditions for laccase-catalyzed bio-transformation of 1-naphthol by response surface methodology (RSM)(Elsevier Sci Ltd, 2008) Ceylan, Hasan; Kubilay, Şenol; Aktaş, Nahit; Şahiner, NurettinResponse surface methodology (RSM) was successfully applied to enzymatic bio-transformation of 1-naphthol. The experiments were conducted in a closed system containing acetone and sodium acetate buffer, with laccase enzyme. Laccase enzyme used as catalyst was derived from Trametes versicolor (ATCC 200801). The enzymatic bio-transformation rate of I-naphthol, based oil measurements of initial dissolved oxygen (DO) consumption rate in the closed system, was optimized by the application of RSM. The independent variables, which had been found as the most effective variables on the initial DO consumption rate by screening experiments, were determined as medium temperature, pH and acetone content. A quadratic model was developed through RSM in terms of related independent variables to describe the DO consumption rate as the response. Based on contour plots and variance analysis, optimum operational conditions for maximizing initial DO consumption rate, while keeping acetone content at its minimum value, were 301 K of temperature, pH 6 and acetone content of 7% to obtain 9.17 x 10(-3) mM DO/min for initial oxidation rate. (c) 2007 Published by Elsevier Ltd.Öğe Aromatic organic contaminant removal from an aqueous environment by p(4-VP)-based materials(Pergamon-Elsevier Science Ltd, 2011) Şahiner, Nurettin; Özay, Özgür; Aktaş, Nahitp(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.Öğe Arsenic (V) removal with modifiable bulk and nano p(4-vinylpyridine)-based hydrogels: The effect of hydrogel sizes and quarternization agents(Elsevier, 2011) Şahiner, Nurettin; Özay, Özgür; Aktaş, 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.Öğe Betaine microgel preparation from 2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide and its use as a catalyst system(Elsevier, 2015) Ajmal, Muhammad; Demirci, Şahin; Siddiq, Mohammad; Aktaş, Nahit; Şahiner, NurettinWe demonstrate the synthesis of poly(sulfobetain methacrylate) (p(SBMA)) hydrogels of micro dimensions by inverse suspension polymerization of a zwitterionic monomer 2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide (SBMA). The prepared microgels were used as microreactors for the synthesis of nickel (Ni) nanoparticles by in situ reduction of Ni (II) loaded into microgels from an aqueous medium. The prepared microgels and microgel metal nanoparticle composites were characterized by Fourier Transformation Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Thermal properties of the microgels were studied by thermal gravimetric analysis (TGA). The amount of Ni nanoparticles generated within the microgels was determined by Atomic Absorption Spectroscopy (AAS) after dissolving the Ni nanoparticles to form Ni (II) ions by treating with concentrated hydrochloric acid (5 M HCl). The prepared composites were used as catalysts for the reduction of nitro aromatic compounds such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP) and 4-nitroaniline (4-NA) and excellent catalytic performances were observed. The effects of temperature and amount of catalyst were also evaluated. A mild activation energy in comparison to the literature was calculated as 35.64 kJ/mol, and very high k p value of 0.42 min(-1) as a function of temperature was estimated for the reduction of 4-NP catalyzed by p(SBMA)-Ni composite catalyst system. (C) 2015 Elsevier B.V. All rights reserved.Öğe Biochar-Embedded Soft Hydrogel and Their Use in Ag Nanoparticle Preparation and Reduction of 4-Nitro Phenol(Taylor & Francis As, 2013) Şahiner, Nurettin; Karakoyun, Necdet; Alpaslan, Duygu; Aktaş, NahitThe authors report the synthesis of a composite hydrogel based on acrylamide-chicken biochar(AAm)-CBand its use as a template in the preparation of silver metal nanoparticles. Moreover, we demonstrate the efficient utilization of p(AAm)-CB composite hydrogel as a reactor vessel in the reduction of an organic contaminant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Experimental parameters affecting 4-NP reduction rate were investigated. The kinetics of the reduction reaction under different reaction conditions were also evaluated to determine the activation parameters. Activation energy for the reduction of 4-NP was 15.25kJmol1 and p(AAm)-CB-Ag composites possessed 99.45% activity after five repetitive uses.Öğe Biocompatible and biodegradable poly(Tannic Acid) hydrogel with antimicrobial and antioxidant properties(Elsevier, 2016) Şahiner, Nurettin; Sağbaş, Selin; Şahiner, Mehtap; Sılan, Coşkun; Aktaş, Nahit; Türk, MustafaA novel resourceful bulk poly(Tannic Acid) (p(TA)) hydrogel was prepared by crosslinking TA molecules with an epoxy crosslinker, trimethylolpropane triglycidyl ether (TMPGDE), in an autoclave at 90 degrees C for 2 h. The obtained p(TA) hydrogels were in disk form and have highly porous morphology. The swelling characteristics of p(TA) hydrogels were investigated in wound healing pH conditions of pH 5.4, 7.4, and 9 at 37.5 degrees C, and the hydrogels showed good swelling and moisture content behavior. Especially, p(TA) hydrogels were found to be sensitive to pH 9 with 1669% maximum swelling. P(TA) hydrogels were completely degraded at pH 9 hydrolytically in 9 days. Total phenol contents and the effects of scavenging ABTS radicals of degraded p(TA) hydrogels at pH 5.4, 7.4, and 9 were evaluated and calculated in terms of gallic acid equivalent and trolox equivalent antioxidant capacity, respectively, and found to be very effective. Moreover, degraded p(TA) hydrogels display strong antimicrobial behavior against gram positive Staphylococcus aureus, Bacillus subtilis, gram negative Pseudomonas aeruginosa bacteria strains and Candida albicans fungus strain. The WST-1 results indicated that bulk p(TA) hydrogels have no cyctotoxicity to the L929 fibroblast cell line in vitro. (C) 2015 Elsevier B.V. All rights reserved.Öğe Boron-containing magnetic nanoparticles from Co, Ni, and Fe chloride salts and their catalytic performances on 4-nitrophenol reduction(Elsevier, 2020) Meydan, Engin; Demirci, Şahin; Aktaş, Nahit; Şahiner, Nurettin; Öztürk, Ömer FarukIn this study, magnetic metal nanoparticles (MNP) were prepared by using Fe, Co and Ni ions and NaBH4 as reducing agents in oil-in-water microemulsion system. The prepared MNP were used as catalyst in 4-Nitro phenol (4-NP) reduction to 4-Aminophenol (4-AP). It was found that magnetic Co MNP performed superior catalytic performances than Fe and Ni MNP for 4-NP reduction. The catalytic reduction experiments revealed that as the concentration of reducing agent, NaBH4 that was used in the preparation of Co MNP was increased, the complete conversion time for 4-NP to 4-AP was decreased as the sizes of Co MNP were obatined as 75 +/- 16, 60 +/- 9, and 37 +/- 6 nm when using 0.1, 0.2 and 0.4 M NaBH, respectively. Therefore, Co MNP prepared by using 0.4 M NaBH4 was used in the detailed investigation of various parameters such as the effect Co nanoparticles, reaction temperatures and time. The activation parameters of Co nanoparticle prepared by using 0.4 M NaBH4 as reducing agent was calculated as Ea = 32.1 +/- 3.1 kJ mot(-1), Delta H = 28.8 +/- 2.2 kJ mot(-1 )and Delta S = - 162.5 +/- 9.4 J mol(-1) K-1 that is the best catalytic performance amongst the other Co MNP5. The shelf life (storage) studies of Co nanoparticles showed that smaller Co MNP obtained by using 0.4 M NaBH4 reduce catalytic performance faster than the others, e.g, in the order of Co MNP(0.4 M NaBH4) > Co MNP(0.2 M NaBH4) > Co MNP(0.1 M NaBH4) in 20 day storage at ambient temperature. The activity% of Co MNP was decreased to 58 +/- 3% after five consecutives use while maintaining 100% conversion at every use corroborating the promising industry application of this magnetic Co MNP.Öğe Catalytic performance of boron-containing magnetic metal nanoparticles in methylene blue degradation reaction and mixture with other pollutants(Elsevier B.V., 2021) Meydan, Engin; Demirci, Şahin; Aktaş, Nahit; Şahiner, Nurettin; Öztürk, Ömer FarukThe catalytic effects of metal nanoparticles (MNPs) synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) microemulsion system by using M(II) salts (M = Fe, Co, Ni) and NaBH4 reducing agent on methylene blue (MB) degradation reaction were investigated. It was determined that Co-MNPs gave the best catalytic activity among them. Influence of the reaction parameters e.g., reaction time, temperature, the size of catalyst and the MNP types on the catalytic performance were studied. It was found that 37 ± 6 nm Co-MNPs revealed the best catalytic activity in all studies. The best activation parameters were calculated as 13.6 ± 1.1 kJ mol−1 and ΔH = 10.7 ± 1.0 kJ mol−1 and ΔS = -87.9 ± 5.4 J mol−1 K−1. The activity % of Co-MNPs was calculated as 85.4 after 30 days on the shelf life study. The reusability studies were carried out and the activity of Co-MNPs at the 5th reuse was calculated as 70 ± 5%. Finally, the catalytic activity of Co-MNPs was investigated inside equal volumes of single and multiple solution mixtures containing MB, 4-Nitrophenol (4-NP) and Eosin Y (EY). In the examinations, it was observed that the nanocatalyst was effective as a reducing agent in all equal amount solutions (MB/4-NP, MB/EY, 4-NP/EY, and MB/4-NP/EY). And also, TOF (mole of MB/4-NP/EY) (mol catalyst.min)−1 values of catalytic activities were also calculated.Öğe COLL 246-Hyaluronic acid hydrogel particles with micron and nano dimensions and their applications in drug delivery(Amer Chemical Soc, 2009) Ilgın, Pınar; Özay, Hava; Aktaş, Nahit; John, Vijay T.; Blake, Diane A.; Ayyala, Ramesh S.; Şahiner, Nurettin[Anstract Not Available]Öğe COLL 490-Colloidal p(4-VP) particles and composites for biomedical application(Amer Chemical Soc, 2009) Özay, Özgür; Aktaş, Nahit; Dülger, Başaran; Sılan, Coşkun; John, Vijay T.; Şahiner, Nurettin[Anstract Not Available]Öğe Complexation of some pendant arm tetraazamacrocyles of Cu(II) and Co(II): Structural, thermodynamic and kinetic studies(Amer Chemical Soc, 2009) Baran, Yakup; Özay, Hava; Aktaş, Nahit; Miyamae, Hiroshi; Şahiner, NurettinÖğe Controllable hydrogen generation by use smart hydrogel reactor containing Ru nano catalyst and magnetic iron nanoparticles(Elsevier, 2011) Şahiner, Nurettin; Özay, Özgür; İnger, Erk; Aktaş, NahitIn 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.Öğe Degradable natural phenolic based particles with micro-and nano-size range(Bentham Science Publishers B.V., 2018) Şahiner, Nurettin; Sağbaş, Selin; Şahiner, Mehtap; Aktaş, NahitBackground: Degradable polymeric particles derived from phenolic compounds are promising materials for biomedical applications due to their inherently antioxidant, antimicrobial, and anticancerogenic properties. We revise all the patent regarding to the biomedical and food additive formulations of Rutin (RT) and Quercetin (QC) as phenolic compounds. Objective: Prepare degradable Poly(Rutin) (p(RT)) and Poly(Quercetin) (p(QC)) particles from natural phenolic compounds, Rutin (RT) and Quercetin (QC). Method: P(RT), and p(QC) particles were prepared using microemulsion crosslinking method employing phenolic compounds such as RT and QC as monomer and poly(ethylene glycol) diglycidyl ether (PEGGE) as a crosslinker in a single step. The degradability of these particles was investigated at physiological conditions, pH 5.4, 7.4, and 9 at 37.5°C. The antioxidant capacity of RT, QC and their corresponding particles was determined by means of total phenol content and ABTS + scavenging assay. The blood compatibility of the particles is determined with hemolysis and blood clotting tests, and the cytotoxicity of the particles on L929 fibroblast cell and A549 cancer cells was done by WST-1 tests. Results: The size of the prepared phenolic particles was in the size range of 0.4-4 ?m with negative zeta potentials,-20.29±1.7 and-31.31±2.0 mV for p(RT) and p(QC) particles, respectively. The highest amount of degradation was obtained for p(QC) particles in almost a linear profile with relatively longer time degrading kinetics at pH 9, e.g., 197±23 mg/g QC was released up to 130 h. The antioxidant capacities of phenolic compounds were decreased about ten-fold upon the particle formations of the phenolic compound, and the antioxidant capacity of p(QC) particles was found to be better than p(RT) particles with 0.22±0.01 and 0.05±0.001 ?mol trolox equivalent g -1 , respectively. The blood compatibility test of p(RT) and p(QC) particles revealed that both particles are blood compatible up to 1 mg/mL concentration and possess clotting of blood over 1 mg/mL concentrations. Furthermore, the cytotoxicity tests showed that p(RT) particles are more biocompatible than p(QC) on the fibroblast cell as 91% cell viability versus 50% for p(QC) was observed at 75 ?g/mL particle concentrations. Additionally, at this concentration 42.3% of cancer cells were inhibited by p(RT) particles. Conclusion: Degradable p(RT) and p(QC) particles that are prepared in a single step offer great avenue for biomedical applications as highly antioxidant materials and with good biocompatibility in contact with blood and fibroblast cells, as well as great anticancerogenic capability against the cancer cells. © 2018 Bentham Science Publishers.Öğe Dicationic poly(4-vinyl pyridinium) ionic liquid capsules as template for Co nanoparticle preparation and H2 production from hydrolysis of NaBH4(Elsevier Science Inc, 2015) Şahiner, Nurettin; Yaşar, Alper O.; Aktaş, NahitPoly(4-vinyl pyridine)-silica (p(4-VP)-silica) composites were synthesized via micro emulsion polymerization, and the capsule of p(4-vinyl pyridine), as cap-p(4-VP), was prepared by removing the core silica from p(4-VP)-silica composites by HF treatment. Dicationic particles in the form of cappoly(4-vinyl pyridine)(++)-1,4-butane (cap-p(4-VP)(++)-C-4), capsule-poly(4-vinyl pyridine)(++)-1,6-hexane (cap-p(4-VP)(++)-C-6), and capsule-poly(4-vinyl pyridine)(++)-1,8-octane (cap-p(4-VP)-C-8) were prepared by modifying cap-p(4-VP) particles with corresponding dibromo alkanes. Then, polymer-metal composites were also prepared from cap-p(4-VP) and dicationic cap-p(4-VP) particles by loading CoCl2 from ethanol and the obtained composites were used in H-2 generation from hydrolysis of NaBH4, and The Ea for the composite catalyst was calculated as 56.53 kJ/mol. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.Öğe Dichromate and arsenate anion removal by PEI microgel, cryogel, and bulkgel(Elsevier Ltd, 2021) Kubilay, Şenol; Demirci, Şahin; Can, Mehmet; Aktaş, Nahit; Şahiner, NurettinAmong the various metal ions, chromate (Cr(VI)) and arsenate (As(V)) are the two most hazardous toxic ion species and are found in nature in the form of dichromate and arsenate anions. In this investigation, polyethyleneimine (PEI)-based hydrogels were prepared with microgel, cryogel, and bulkgel morphologies employing glycerol diglycidyl ether as a crosslinker. The prepared PEI-based hydrogels were used to remove dichromate and arsenate anions from aqueous media. PEI microgel, cryogel, and bulkgels weighing 50 mg of each adsorbed 84.7 ± 0.8, 76.5 ± 5.2, and 108.9 ± 2.4 mg.g-1 of dichromate anions and 15.9 ± 0.7, 45.4 ± 1.9, and 79.2 ± 11.6 mg.g-1 of arsenate anions in 30, 120, and 240 min, respectively. The dichromate and arsenate anions adsorption of PEI-based hydrogels were found to fit to the pseudo-second-order kinetic, and nonlinear Langmuir isotherm models, respectively with higher R2 values. The highest distribution coefficient (Kd) value of PEI-based hydrogels for dichromate adsorption was obtained on the cryogel forms of PEI as 1.89 ± 0.05. Likewise, the highest Kd value for the arsenate adsorption was calculated on PEI-based bulkgels as 0.46 ± 0.01. The thermodynamic parameters of PEI based hydrogels in the adsorption of dichromate and arsenate anions e.g., ΔG (all negative (except for the arsenate adsorption by PEI microgels), and ΔH that is around 2-10 kJ.mol-1, and ΔS what is around 0.01-0.02 kJ.mol-1. K-1 were calculated. The reusability studies showed that PEI-based hydrogels can be used for at least 5 consecutive adsorption-desorption cycles with almost 70 % anion removal efficiency after the fifth cycle.
