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Öğe Biosynthesis of Linden Protected Silver Nanoparticles and their Safe Application as a Catalyst for Reduction of Methylene Blue Hydrate(IEEE, 2017) Unver, Yasemin; Altun, Turkan; Pehlivan, Erol; Hussain, Masood; Avci, AhmetGreen synthetic protocol was developed for fabrication of silver nanoparticles (AgNPs) using linden extract as stabilizing and reducing agent. Green synthetic protocols preferred over other reduction procedures due to its nontoxic, easy, nonexpensive and environmental friendly behavior. The effect of various reaction parameters and additives on morphology such as, concentration of silver nitrate, effect of pH, temperature, volume of extract and stirring rate were optimized in order to achieve small size stable silver nanoparticles by using Ultra Violet-Visible (UV-Vis) spectroscopy. Trasmission electron microscopy (TEM) was performed to study the morphology and dimensions of biologically synthesized silver nanoparticles. TEM study confirmed that the synthesized nanoparticles were spherical in nature having an average size of 24.4 +/- 2nm. The synthesized plant protected AgNPs were applied homogeneously as well as heterogeneously for reduction of methylene blue hydrate (MB) by immobilizing the nanoparticles on small pieces of glass cover slip. These NPs act as an efficient heterogeneous catalyst and completely reduced MB within 8 min.Öğe Determination of some inorganic metals in edible vegetable oils by inductively coupled plasma atomic emission spectroscopy (ICP-AES)(CONSEJO SUPERIOR INVESTIGACIONES CIENTIFICAS-CSIC, 2008) Pehlivan, Erol; Arslan, Gulsin; Gode, Fethiye; Altun, Turkan; Oezcan, M. MusaSeventeen edible vegetable oils were analyzed spectrometrically for their metal (Cu, Fe, Mn, Co, Cr, Pb, Cd, Ni, and Zn) contents. Toxic metals in edible vegetable oils were determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The highest metal concentrations were measured as 0.0850, 0.0352, 0.0220, 0.0040, 0.0010, 0.0074, 0.0045, 0.0254 and 0.2870 mg/kg for copper in almond oil, for iron in corn oil-(c), for manganese in soybean oil, for cobalt in sunflower oil-(b) and almond oil, for chromium in almond oil, for lead in virgin olive oil, for cadmium in sunflower oil-(e), for nickel almond oil and for zinc in almond oil respectively. The method for determining toxic metals in edible vegetable oils by using ICP-AES is discussed. The metals were extracted from low quantities of oil (2-3 g) with a 10% nitric acid solution. The extracted metal in acid solution can be injected into the ICP-AES. The proposed method is simple and allows the metals to be determined in edible vegetable oils with a precision estimated below 10% relative standard deviation (RSD) for Cu, 5% for Fe, 15% for Mn, 8% for Co, 10% for Cr, 20% for Pb, 5% for Cd, 16% for Ni and 11% for Zn.Öğe Hexavalent chromium removal using agricultural waste "rye husk"(TAYLOR & FRANCIS INC, 2016) Altun, Turkan; Parlayici, Serife; Pehlivan, ErolThe adsorption of Cr(VI) on rye husk (RH) was studied at varying Cr(VI) concentrations, adsorbent dose, contact time, and pH. Maximum Cr(VI) was sequestered from the solution within 140 min and the maximum removal of 5.0 mM Cr(VI) was about 68% at pH of 3.0 for 0.5 g RH. The removal of Cr(VI) was maximum (80.0%) when the initial pH of the solution was kept at 3.0. The Cr(VI) adsorption capacity of RH samples was calculated as 0.435 mmol/g at pH 3.0 from Langmuir isotherm. The adsorption kinetics data were evaluated with first-order reversible and pseudo-second-order kinetics models.Öğe Ion-exchange of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ions from aqueous solution by Lewatit CNP 80(ELSEVIER, 2007) Pehlivan, Erol; Altun, TurkanRemoval of trace amounts of heavy metals can be achieved by means of selective ion-exchange processes. The newly developed resins offered a high resin capacity and faster sorption kinetics for the metal ions such as Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ions. In the present study, the removal of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resin Lewatit CNP 80 (weakly acidic) and were compared with Lewatit TP 207 (weakly acidic and chelating). The optimum pH range for the ion-exchange of the above mentioned metal ions on Lewatit CNP 80 and Lewatit TP 207 were 7.0-9.0 and 4.5-5.5, respectively. The influence of pH, contact time, metal concentration and amount of ion-exchanger on the removal process was investigated. For investigations of the exchange equilibrium, different amounts of resin were contacted with a fixed volume of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ion containing solution. The obtained sorption affinity sequence in the presented work was Ni2+ > Cu2+ > Cd2+ > Zn2+ > Pb2+. The metal ion concentrations were measured by AAS methods. The distribution coefficient values for metal ions of 10(-3) M initial concentration at 0.1 mol/L ionic strength show that the Lewatit CNP 80 was more selective for Ni2+, Cu2+ than it was for Cd2+, Zn2+ and Pb2+. Langmuir isotherm was applicable to the ion-exchange process and its contents were calculated. The uptake of metal ions by the ion-exchange resins was reversible and thus has good potential for the removal of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ from aqueous solutions. The amount of sorbed metal ion per gram dry were calculated as 4.1, 4.6, 4.7, 4.8, and 4.7 mequiv./g dry resin for Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+, respectively. Selectivity increased in the series: Cd2+ > Pb2+ > Cu2+ > Ni2+ > Zn2+. The results obtained showed that Lewatit CNP 80 weakly acidic resin had shown better performance than Lewatit TP 207 resin for the removal of metals. The change of the ionic strength of the solution exerts a slight influence on the removal of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+. The presence of low ionic strength or low concentration of NaNO3 does not have a significant effect on the ion-exchange of these metals by the resins. We conclude that Lewatit CNP 80 can be used for the efficient removal of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ from aqueous solutions. (c) 2006 Elsevier B.V. All rights reserved.Öğe Removal of Cr (VI) from aqueous solution by pyrolytic charcoals(ELSEVIER SCIENCE BV, 2016) Altun, Turkan; Kar, YakupBio-chars produced by the pyrolysis of walnut shells at 450 degrees C (BC450) and theco-pyrolysis of walnut shells and 20 wt% tar sand (BCTS20) at the same temperature, were investigated as potential adsorbents for the removal of Cr(VI) ions from aqueous solutions using batch experiments. The BCTS20 has more abundant surface functional groups than BC450. The Cr(VI) removal percentages under optimal conditions were 80.47and 95.69% for BC450 and BCTS20, respectively. Langmuir, Freundlich and D-R models were used to fit the adsorption isotherms and the Langmuir model described the adsorption isotherms best. The adsorption of Cr(VI) was by a chemical process dominated by ion-exchange, electrostatic attraction and chelation. The maximum Langmuir adsorption capacities were 36.55 and 49.76 mg per g of BC450 and BCTS20, respectively. The maximum Langmuir adsorption capacity of BCTS20 is comparable to that of some reported commercial activated carbons.