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Öğe Benign Preparation of Metal-Organic Frameworks of Trimesic Acid and Cu, Co or Ni for Potential Sensor Applications(Springer, 2015) Sel, Kivanc; Demirci, Şahin; Meydan, Engin; Yildiz, Sema; Ozturk, Omer Faruk; Al-Lohedan, Hamad; Şahiner, NurettinMetal-organic frameworks (MOFs) have been constructed using trimesic acid (TMA) as organic linker and Co(II), Ni(II) or Cu(II) metal ions from their corresponding aqueous chloride salts at room temperature. The prepared TMA-M (M: Co, Ni, and Cu) MOFs have been characterized in terms of their porosity and optical, thermal, electrical, and structural properties. The prepared MOFs were characterized in terms of their porosity through Brunauer-Emmett-Teller measurements, yielding a value of 330 m(2)/g for the TMA-Cu MOF. Structural analysis and thermal characterization of the prepared MOFs were done by using Fourier-transform infrared (FT-IR) spectroscopy, x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), respectively. The optical properties were analyzed by fluorescence spectroscopy. Additionally, TMA-M MOF disks were prepared and their conductivities determined by room-temperature I-V measurements. The conductivity of the TMA-M MOFs was calculated to be between 7.97 x 10(-7) S/cm and 5.39 x 10(-9) S/cm.Öğe Cationic microgels embedding metal nanoparticles in the reduction of dyes and nitro-phenols(Elsevier Science Sa, 2015) Rehman, Saif Ur; Siddiq, Mohammed; Al-Lohedan, Hamad; Şahiner, NurettinCationic microgels of p(3-Acrylamidopropy1)-trimethylammonium chloride (p(APTMACI)) were synthesized using the inverse suspension polymerization technique, and the obtained microgels were used as microreactor for in situ synthesis of Co, Ni, and Cu nanoparticles. The p(APTMAC1) microgels were loaded with Co,.Ni, and Cu after contact with chloride salts of the metals, CoCl2, NiCl2, and CuCl2, in ethanol and reduced to their respective metal nanoparticles by treating them with sodium borohydride (NaBH4) as reducing agent. The metal nanoparticle content of p(APTMAC1) microparticles were quantified for each composites by atomic absorption spectroscopy (AAS) after dissolution of the metal nanoparticles within microgel composites by concentrated hydrochloric acid (HCI). Dynamic light scattering (DIS) was used to monitor zeta potential of the microgel composites. Thermal properties of both cationic p(APTMAC1) microgel and its composites were investigated with a thermal gravimetric analyzer (TGA). It was also found that the p(APTMAC1) composites performed as excellent catalyst systems in the reduction of different aromatic pollutants like 2-nitrophenol, 4-nitrophenol and fluorescent dyes like eosin Y(EY), and methyl orange (MO). Various parameters such as metal types, and their respective amount, and temperature were investigated to determine the catalytic performances of the microgel-metal nanoparticle composites. (C) 2014 Elsevier B.V. All rights reserved.Öğe Environmental application of PEI based hydrogels in different morphology and sizes: Bulk, microgel, and cryogel(Amer Chemical Soc, 2015) Şahiner, Nurettin; Demirci, Şahin; Şahiner, Mehtap; Al-Lohedan, Hamad; Aktas, Nahit[Anstract Not Available]Öğe Fast removal of high quantities of toxic arsenate via cationic p(APTMACl) microgels(Academic Press Ltd- Elsevier Science Ltd, 2016) Rehman, Saif Ur; Siddiq, Mohammed; Al-Lohedan, Hamad; Aktas, Nahit; Şahiner, Mehtap; Demirci, Şahin; Şahiner, NurettinHydrogels are resourceful materials and can be prepared in different morphology, size, surface charge and porosity adopting different polymerization techniques and reaction conditions. The cationic poly(3-acrylamidopropyl)trimethylammonium chloride (p(APTMACl)) microgels were synthesized by photo-initiated inverse suspension polymerization technique. These microgels were utilized as absorbents for the removal of toxic arsenate (As) from different aqueous environments. The experimental parameters affecting absorption efficiency were investigated, and it was demonstrated that these types of microgels are highly efficient in removing arsenate anions from different aqueous environments compared to the previously reported bulk hydrogel, and cryogel of the same material. A removal efficiency of approximately 97.25% was obtained by immersing 0.5 g microgel in 250 ppm 100 mL solution of arsenate anions for 60 min. Both Langmuir and Freundlich adsorption isotherms were applied to adsorption of arsenate anions by p(APTMACl) microgels, and the Langmuir isotherm was a better representation of the adsorption of arsenate with a high value of R-2 (0.9982). Furthermore, mag-p(APTMACl) microgels were synthesized for the adsorption of arsenate anions to provide easy removal of the microgel composite by using an externally applied magnetic field. Furthermore, re-usability of the p(APTMACl) microgels was also investigated for the adsorption of arsenate anions. CD 2015 Elsevier Ltd. All rights reserved.Öğe Macroporous cryogel metal nanoparticle composites for H2 generation from NaBH4 hydrolysis in seawater(Elsevier Science Bv, 2015) Şahiner, Nurettin; Yıldız, Sema; Şahiner, Mehtap; Issa, Zuheir A.; Al-Lohedan, HamadPoly( 2-hydroxy ethyl methacrylate) p(HEMA), poly( acrylic acid) p(AAc), poly(3-sulfopropyl methacrylate) p(SPM), and poly(4-vinylpyridine) p(4-VP) cryogels from various monomers containing functional groups such as COOH, SO3H, and OH, and) N monomer were synthesized under cryogenic conditions via free radical polymerization technique. The synthesized cryogels were used as templates for metal nanoparticle synthesis using Co and Ni, and the prepared composite cryogels were utilized in hydrogen (H-2) generation from the hydrolysis reaction of NaBH4. It was found that the hydrolysis reaction of NaBH4 in seawater is much faster than in DI water when using the p(SPM)-Co catalyst system. Parameters such as water and metal types for different cryogels, concentration of NaBH4, amount of metal catalyst, and temperature were investigated. The hydrogen generation rate (HGR) and turnover frequency (TOF) values were also investigated for temperature dependency. It was found that as the temperature increased from 30 to 70 degrees C, the HGR and TOF increased from 1288.0 +/- 61.2 (ml H-2) (g of metal min)(-1) and 3.1 +/- 0.1 mol H-2 (mol metal min)(-1) to 7707.8 +/- 179.4 (ml H-2) (g of metal min)(-1), and 16.1 +/- 0.4 mol H-2 (mol metal min)(-1), respectively. The activation energy, enthalpy, and entropy were 31.1 kJ (mol K)(-1), 27.7 kJ (mol K)(-1), and 196.4J (molK)(-1), respectively, for NaBH4 hydrolysis catalyzed in seawater by p(SPM)-Co composite system. (C) 2015 Elsevier B.V. All rights reserved.Öğe Super-fast hydrogen generation via super porous Q-P(VI)-M cryogel catalyst systems from hydrolysis of NaBH4(Pergamon-Elsevier Science Ltd, 2015) Şahiner, Nurettin; Seven, Fahriye; Al-Lohedan, HamadNovel poly(1-vinyl imidazole) p(VI) cryogels were synthesized via cryopolymerization technique where simultaneous polymerization and crosslinking occur around ice crystals under freezing conditions. The superporous p(VI) cryogels were modified with various alkyl bromides possessing different chain lengths such as 1.2-Dibromoethane (1,2-BE), 1.4-Dibromobutane (1,2-BB) and 1.6-Dibromohexane (1,6-BH), and used as template for in situ metal nanoparticle (M) synthesis (M: Co-0 or Ni-0). The prepared p(VI)-M cryogel composites were used in hydrogen (H-2) generation from the hydrolysis of sodium borohydride (NaBH4). Very high turnover frequency (TOP) and H-2 generation rate (HGR) values, of 34.4 (mol H-2) (mol catalyst min)(-1) and 14566.9 (mL H-2) (min)(-1) (g of M)(-1), respectively, were obtained at 70 degrees C for 3rd time Co (II) loaded and reduced 1.2-BE modified p(VI)-Co composite catalyst system compared with other imidazole-based catalyst systems reported in the literature. Moreover, modified p(VI) cryogels possess inherently magnetic behavior even after a single Co(II) loading-reduction step. Due to their superior properties, such as being recoverable via external applied magnetic field, fast HGR, and reusability, 1.2-BE-p(VI)-Co metal composites were found to be a highly attractive catalyst system for catalytic hydrolysis of NaBH4. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe The resourcefulness of p(4-VP) cryogels as template for in situ nanoparticle preparation of various metals and their use in H2 production, nitro compound reduction and dye degradation(Elsevier, 2015) Şahiner, Nurettin; Yildiz, Sema; Al-Lohedan, HamadPoly(4-vinylpyridine) (p(4-VP)) cryogels were synthesized under cryogenic conditions (T=-18 degrees C) and were converted to positively charged forms by modifying with different alkyl dihalides of variable chain lengths such as 1,2-dibromoethane (1,2 BE), 1,4-dibromobutane (1,4 BB), 1,6-dibromohexane (1,6 BH), and 1,8-dibromooctane (1,8 BO). The chemical structure of synthesized supermacroporous 1,4 BB-p(4-VP) cryogels were confirmed by FT-IR spectroscopy. The 1,4 BB modified-poly(4-vinylpyridine) (1,4 BB-p(4-VP)) cryogels were used as template for in situ metal nanoparticle preparation as 1,4 BB-p(4-VP)-M (M: Co, Ni, Cu, and Fe) using chloride salts of Co, Ni, Cu, and Fe in ethanol. These metal-nanoparticle macroporous cryogel composites were employed in H-2 generation from hydrolysis of sodium borohydride (NaBH4). Metal nanoparticles embedded 1,4 BB-p(4-VP)-M were visualized by TEM, and thermal behavior of 1,4 BB-p(4-VP) cryogels were done by thermogravimetric analyzer (TGA). The metal content of 1,4 BB-p(4-VP)-M was estimated via atomic absorption spectroscopy (AAS). Multiple metal salt loading and reduction cycles were performed for 1,4 BB-p(4-VP) cryogels to increase the amount of contained Co. The activation energies, enthalpy, and entropy for NaBH4 hydrolysis catalyzed by 1,4 BB-p(4-VP)-Co cryogel composites were determined as 47.6 kJ (mol)(-1), 46.2 kJ (mol K)(-1), and 146.91 (mol K)(-1), respectively. The cryogel network embedded with Co, Ni, Cu, and Fe nanoparticles was also used as a catalyst in the reduction of 4-nitrophenol (4-NP) in an aqueous solution in excess amount of NaBH4. Furthermore, the Cu metal nanoparticle-containing 1,4 BB-p(4-VP) cryogel was utilized in the degradation of methylene blue (MB). (C) 2014 Elsevier B.V. All rights reserved.Öğe The synthesis of desired functional groups on PEI microgel particles for biomedical and environmental applications(Elsevier, 2015) Şahiner, Nurettin; Demirci, Şahin; Şahiner, Mehtap; Al-Lohedan, HamadPolyethyleneimine (PEI) microgels were synthesized by micro emulsion polymerization technique and converted to positively charged forms by chemical treatments with various modifying agents with different functional groups, such as 2-bromoethanol (-OH), 4-bromobutyronitrile ( -CN), 2-bromoethylamine hydrobromide (-NH2), and glycidol ( -OH). The functionalization of PEI microgels was confirmed by FT-IR, TGA and zeta potential measurements. Furthermore, a second modification of the modified PEI microgels was induced on 4-bromo butyronitrile-modified PEI microgels (PEI-CN) by amidoximation, to generate new functional groups on the modified PEI microgels. The PEI and modified PEI microgels were also tested for their antimicrobial effects against various bacteria such as Bacillus subtilis ATCC 6633, Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 25323. Moreover, the PEI-based particles were used for removal of organic dyes such as methyl orange (MO) and congo red (CR). The absorption capacity of PEI-based microgels increased with modification from 101.8 mg/g to 218.8 mg/g with 2-bromoethylamine, 216.2 m/g with 1-bromoethanol, and 224.5 mg/g with 4-bromobutyronitrile for MO. The increase in absorption for CR dyes was from 347.3 mg/g to 390.4 mg/g with 1-bromoethanol, 399.6 mg/g with glycidol, and 349.9 mg/g with 4-bromobutyronitrile. (C) 2015 Elsevier B.V. All rights reserved.Öğe The use of superporous p(3-acrylamidopropyl)trimethyl ammonium chloride cryogels for removal of toxic arsenate anions(Academic Press Ltd- Elsevier Science Ltd, 2015) Şahiner, Nurettin; Demirci, Şahin; Şahiner, Mehtap; Yilmaz, Selahattin; Al-Lohedan, HamadPoly((3-Acrylamidopropyl)trimethylammonium chloride) (p(APTMACl)) cryogels were used as a superporous polymer network for the removal of toxic arsenate anions from an aqueous medium. The fast swelling in water, in about 7 s, was shown to be very useful leading to fast arsenate adsorption by p(APTMACl) cryogels within 30 min in comparison to 12 h for bulk common p(APTMACl) hydrogels. A maximum adsorption capacity of about 120 (mg/g) arsenate was obtained for p(APTMACl) cryogels. Both the Langmuir and Freundlich adsorption isotherms were applied for adsorption of arsenate anions by p(APTMACl) cryogels, and it was observed that the adsorption of arsenate anions by p(APTMACl) cryogels are represented better via Langmuir adsorption isotherm providing the R-2 value of 0.998. Furthermore, mag-p(APTMACl) cryogels were synthesized, and shown to be very useful in the fast removal of toxic arsenate anions. The mag-p(APTMACl) cryogels including the adsorbed arsenate were removed by an externally applied magnetic field, with some reduction in the arsenate ion adsorption capacity. It was also further demonstrated that p(APTMACl) cryogels can be reused in the adsorption of arsenate 5 times from aqueous environments without significant loss of adsorption capacity, from 113.47 +/- 9 to 102.67 +/- 6 mg/g. (C) 2015 Elsevier Ltd. All rights reserved.
