Yazar "Saf, Ahmet O." seçeneğine göre listele

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    Kinetic study on removal of toxic metal Cr(VI) through a bulk liquid membrane containing p-tert-butylcalix[4]arene derivative
    (ELSEVIER, 2011) Alpaydın, Sabri; Saf, Ahmet O.; Bozkurt, Selahattin; Sirit, Abdulkadir
    The transport of Cr(VI) from aqueous solutions through bulk liquid membrane was studied using p-tert-butylcalixpliarene 3-diethylaminopropyl diamide derivative as a carrier. The aqueous solution of potassium dichromate was used as the model contaminant. The kinetic parameters (k(1), k(2), t(max), R-m(max), J(d)(max) and J(a)(max)) for the forward and the back extraction were calculated by means of Cr(VI) concentrations of the donor and the acceptor phase. The results showed that it was possible to transport 96.65% of Cr(VI) from the acidic donor solutions to the acceptor solutions at the optimum operating conditions after 10 h contact time. The highest transport efficiency was observed at pH 2 in the donor phase and at pH 5 in the acceptor phase. It was shown that the transport of Cr(VI) stem from pH difference between the donor and the acceptor phases. The activation energy values were calculated as 5.77 and 7.99 kJmol(-1) for the forward and the back extraction, respectively. It was indicated that the process was diffusionally controlled by dichromate anions. The experimental results demonstrated that p-tert-butylcalix[4]arene derivative was an effective carrier for the transport of Cr(VI). (C) 2011 Elsevier B.V. All rights reserved.
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    Selective transport and removal of Cr(VI) through polymer inclusion membrane containing 5-(4-phenoxyphenyl)-6H-1,3,4-thiadiazin-2-amine as a carrier
    (ELSEVIER, 2011) Saf, Ahmet O.; Alpaydın, Sabri; Coşkun, Ahmet; Ersöz, Mustafa
    In this study, the transport of Cr(VI) ions through polymer inclusion membrane (PIM) containing 5(4-phenoxyphenyl)-6H-1,3,4-thiadiazin-2-amine (FFAT) firstly used as a carrier from acidic aqueous solution into CH3COONH4 aqueous solution was presented. PIM was characterized by AFM. FTIR techniques and contact angle measurements. The efficiency of Cr(VI) transport through PIM was optimized as a function of the donor and acceptor phase compositions as well as the membrane composition. The transport efficiency of Cr(VI) was obtained as 89.83% after 10 h under the optimized conditions. Also, a selective removal experiment of Cr(VI) ions from electroplating wastewater including Cr(VI), Cu(II), Ni(II), AI(III) and Fe(III) was performed and the selective removal of Cr(VI) was successfully carried out with the recovery factor of 43.29%. This novel PIM containing FFAT as a carrier exhibited an excellent Cr(VI) transport characteristic and a high selectivity for Cr(VI) ions among other heavy metal ions. It was observed that FFAT can be used as a carrier in PIMs for transport of Cr(VI). (C) 2011 Elsevier B.V. All rights reserved.
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    Synthesis of Novel Tripodal-Benzimidazole From 2,4,6-Tris(P-Formylphenoxy)-1,3,5-Triazine: Structural, Electrochemical and Antimicrobial Studies
    (ELSEVIER SCIENCE BV, 2010) Koç, Ziya Erdem; Bingöl, Haluk; Saf, Ahmet O.; Torlak, Emrah; Coşkun, Ahmet
    Four new tripodal-benzimidazole derivatives were synthesized by Schiff base reaction between 2,4,6-tris(p-formylphenoxy)-1,3,5-triazine (TRIPOD) and different diamine derivatives. The structures of the obtained compounds were identified by FT-IR, (1)H NMR, (13)C NMR and UV-vis spectral data, thermal analysis and elemental analysis. Electrochemical behaviors of the compounds were studied by cyclic voltammetry in DMF including 0.1 M [NBu(4)] [PF(6)]. The voltammograms showed peaks having similar characteristics except tripodal-benzimidazole including -NO(2) derivative. In addition, their antimicrobial activities were evaluated by using the standard disk diffusion method in dimethylformamide media. The activities were determined against 4 bacteria cultures by comparing to those of gentamycin.
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    Transport kinetics of chromium(VI) ions through a bulk liquid membrane containing p-tert-butyl calix[4]arene 3-morpholino propyl diamide derivative
    (ELSEVIER SCIENCE BV, 2006) Saf, Ahmet O.; Alpaydın, Sabri; Sirit, Abdulkadir
    The transport of chromate ions (Cr2O72-) from an aqueous solution into an aqueous receiving solution through a bulk liquid membrane containing p-tert-butyl calix[4]arene 3-morpholino propyl diamide as a carrier was examined. The influence of pH on donor and acceptor phase, effect of chromate and carrier concentration, type of solvent, stirring speed and temperature were investigated. The kinetic parameters (k(1), k(2), t(max) R-m(max), J(d)(max), J(a)(max)) were calculated for the interface reactions assuming two consecutive, irreversible first order reactions. The activation energy values are 24.83 kJ mol(-1) for extraction and 5.14kJ mol(-1) for reextraction. These values indicate that the process is diffusionally controlled by chromate ions. The experiments demonstrated that calix[4]arene diamide derivative is a good carrier for Cr(VI) transport through liquid membranes in this study. (c) 2006 Elsevier B.V. All rights reserved.
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    Voltammetric discrimination of mandelic acid enantiomers
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2014) Zor, Erhan; Saf, Ahmet O.; Bingol, Haluk; Ersoz, Mustafa
    We report a novel electrochemical biosensor for direct discrimination of D- and L-mandelic acid (D- and L-MA) in aqueous medium. The glassy carbon electrode (GCE) surface was modified with reduced graphene oxide (rGO) and gamma-globulin (GLOB). Electrochemical characterization of the modified electrodes was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode surfaces were also characterized by scanning electron microscopy. Electrochemical response of the prepared electrode (GCE/rGO/GLOB) for discrimination of D- and L-MA enantiomers was investigated by cyclic voltammetry and was compared with bare GCE in the concentration range of 2 to 10 mM. Whereas the bare GCE showed no electrochemical response for the MA enantiomers, the GCE/rGO/GLOB electrode exhibited direct and selective discrimination with different oxidation potential values of 1.47 and 1.71 V and weak reduction peaks at potential values of -1.37 and -1.48 V, respectively. In addition, electrochemical performance of the modified electrode was investigated in mixed solution of D- and L-MA. The results show that the produced electrode can be used as electrochemical chiral biosensor for MA. (C) 2013 Elsevier Inc. All rights reserved.