Browsing by Author "Kocak S."

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    Enhanced optical oxygen sensing using a newly synthesized ruthenium complex together with oxygen carriers
    (Elsevier, 2003) Ertekin K.; Kocak S.; Ozer M.S.; Aycan S.; Cetinkaya B.
    In this article, an emission based, simple and fast method is proposed for the determination of gaseous oxygen. A newly synthesized fluorophore, dichloro-{2,6-bis[1-(4-dimethylamino-phenylimino) ethyl]pyridine}ruthenium(II) has been used for oxygen sensing together with oxygen carrier perfluorochemicals (PFCs) in silicon matrix. It should be noted that the solubility of oxygen in fluorocarbons is about three to ten times large as that observed in the parent hydrocarbons or in water, respectively. Employed PFCs are chemically and biochemically inert, have high dissolution capacities for oxygen, and, once doped into sensing film, considerably enhance the response of sensing agent. © 2003 Elsevier B.V. All rights reserved.
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    A novel ethanol biosensor on pulsed deposited MnOx-MoOx electrode decorated with Pt nanoparticles
    (Elsevier B.V., 2016) Ozdokur K.V.; Demir B.; Atman E.; Tatli A.Y.; Yilmaz B.; Demirkol D.O.; Kocak S.; Timur S.; Ertas F.N.
    Transition metal oxides provide low cost alternatives to noble metals due to their unique electrocatalytic and electrochromic properties and display strong interactions with noble metal nanoparticles. Present study describes the use of mixed molybdenum and manganese oxide film electrode enriched with platinum nanoparticles to enhance the catalytic performance in the oxygen reduction reaction (ORR). The mixed oxide film, denominated as GCE/MnOx-MoOx/Pt, was co-deposited by pulsed potential deposition technique and then, it was used as an immobilization matrix for the intact bacterial cells. The resulted whole cell biosensor has served as a sensing platform for ethanol detection by monitoring of oxygen consumption as a result of the bacterial metabolism in the presence of the substrate. Following the optimization experiments, GCE/MnOx-MoOx/Pt/Gluconobacter oxydans biofilm was applied to investigate the analytical characteristics and response time to ethanol as well as operational stability and substrate specificity for other carbon sources. The linear range was found as 0.075–5.0 mM with a response time of 63 s and the developed method was applied to the ethanol determination in alcoholic drinks. Satisfactory recovery figures were obtained in comparison to the standard method. © 2016 Elsevier B.V.
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    Uptake characteristics of Pb(II), Cu(II) and Zn(II) by natural magnetite: Application to river samples
    (Scibulcom Ltd., 2017) Erdem Yayayuruk A.; Yayayuruk O.; Kocak C.C.; Kocak S.
    Natural magnetite was investigated for the removal of Pb(II), Cu(II) and Zn(II) ions from water samples. The optimum experimental conditions including pH, sorbent amount and contact time have been established. Langmuir isotherm model was found to be more suitable to represent the experimental equilibrium than Freundlich isotherm model. The experimental kinetic data were a better fit with pseudo-second order reactions rather than pseudo-first order equation. The sorbent selectively removed Pb(II), Cu(II) and Zn(II) ions in the presence of several competitor ions (≥ 98%). The application of the sorbent for the removal of Pb(II), Cu(II) and Zn(II) ions from ultrapure and river waters gave applicable results (> 90%) with high accuracy and precision. Thus, natural magnetite was found to be useful for the removal of these metal ions and its low toxicity, good biocompatibility, small size and being inexpensive makes it a good promising candidate material for water treatment studies.