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Öğe Adsorption of phenol from aqueous solution on a low-cost activated carbon produced from tea industry waste: Equilibrium, kinetic, and thermodynamic study(American Chemical Society, 2012) Gundogdu A.; Duran C.; Senturk H.B.; Soylak M.; Ozdes D.; Serencam H.; Imamoglu M.The ability of activated carbon which was produced by chemical activation using zinc chloride from tea industry wastes (TIWAC) to adsorb phenol molecules from aqueous solution was tested by equilibrium, kinetic, and thermodynamic parameters. Phenol adsorption on TIWAC took place with a high yield at pH values in the range 4 to 8. The optimum contact period was observed as 4.0 h and from the adsorption graphs plotted as a function of time; it was established that phenol adsorption on TIWAC conformed more to a pseudosecond-order kinetic model. Additionally, it was determined that the adsorption rate is controlled by intraparticle diffusion as well as film diffusion. It was established that phenol adsorption on TIWAC can be better defined by the Langmuir adsorption model and its adsorption capacity was 142.9 mg·g-1 from the linear Langmuir equation. Temperature had an adverse effect on adsorption yield, and hence, the adsorption process was exothermic in our case. Moreover, increasing electrolyte concentration in the medium has a positive effect on adsorption yield. From the data obtained, it was concluded that the removal of phenol from aqueous solution by TIWAC produced from tea industry wastes with a very low cost took place with an extremely high performance. © 2012 American Chemical Society.Öğe Application of carrier element free coprecipitation (CEFC) method for determination of Co(II), Cu(II) and Ni(II) ions in food and water samples(2013) Serencam H.; Duran C.; Ozdes D.; Bektas H.A simple and highly sensitive separation and preconcentration procedure, which has minimal impact on the environment, has been developed. The procedure is based on the carrier element free coprecipitation (CEFC) of Co(II), Cu(II), and Ni(II) ions by using 2-{4-[2-(1H-indol-3-yl)ethyl]-3-(4-methylbenzyl)-5-oxo- 4,5-dihydro-1H-1,2,4-triazol- 1-yl}-N'-(pyridin-2-yl methylidene)acetohydrazide (IMOTPA), as an organic coprecipitant. The levels of analyte ions were determined by flame atomic absorption spectrometry (FAAS). The detection limits for Co(II), Cu(II) and Ni(II) ions were found to be 0.40, 0.16 and 0.17 ?g L-1, respectively, and the relative standard deviations for the analyte ions were lower than 3.0%. Spike tests and certified reference material analyses were performed to validate the method. The method was successfully applied for the determination of Co(II), Cu(II) and Ni(II) ions levels in sea and stream water as liquid samples and red pepper, black pepper, and peppermint as solid samples.Öğe Assessment of kinetics, thermodynamics, and equilibrium parameters of Cu(II) adsorption onto Rosa canina seeds(Taylor and Francis Inc., 2014) Serencam H.; Ozdes D.; Duran C.; Senturk H.B.Rosa canina seeds (RCS) is considered as a low-cost and promising adsorbent in removal of metal ions; hence, in the present study, we aimed to test the adsorptive removal of Cu(II) ions from aqueous solutions by utilizing RCS in a batch process. After characterization of RCS by using several techniques, the effects of various experimental parameters such as initial pH of aqueous solution, contact time, initial Cu(II) concentration, RCS concentration, temperature, and electrolyte concentration were studied upon the adsorption process. The desorption conditions of Cu(II) ions from the loaded RCS were also evaluated. Maximum Cu(II) adsorption was found to occur at pH 6.0 and the equilibrium was established after 60 min of contact time. The adsorption isotherms were described by means of Langmuir, Freundlich, Temkin, and Dubinin Radushkevich models. The adsorption kinetics were analyzed using pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models and the adsorption data were well described by the pseudo-second-order model. Thermodynamic parameters such as the Gibbs free energy (?G), enthalpy (?H), and entropy (?S) changes were also evaluated and it has been found that the adsorption process was feasible, spontaneous, and endothermic in the temperature range of 278-313 K. © 2013 Balaban Desalination Publications. All rights reserved.Öğe Biosorption properties of Morus alba L. for Cd (II) ions removal from aqueous solutions(2013) Serencam H.; Ozdes D.; Duran C.; Tufekci M.The abundantly available industrial waste product Morus alba L. pomace (MAP) is one of the cost-effective biosorbent for removal of metal ions from aqueous solutions. Hence, in the present study, we aimed to test the ability of MAP to remove Cd(II) ions through batch biosorption process. Firstly, MAP was characterized using several techniques, and then the influence of various experimental parameters such as initial pH of the aqueous solution, initial Cd(II) concentration, contact time, MAP concentration, and temperature were evaluated upon the biosorption process. It was found that the maximum uptake of Cd(II) ions occurred at initial pH 6.0 and optimum contact time was observed as 60 min. Cd(II) ions adsorption on MAP analyzed by the Langmuir and Freundlich isotherm models and the maximum monolayer biosorption capacity of MAP was found to be 21.69 mg g -1 by using the Langmuir isotherm model. The pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models were employed to describe the biosorption kinetics. In order to investigate the thermodynamic properties of the biosorption process, the changes in the Gibbs free energy (â?†G), enthalpy (â?†H), and entropy (â?†S) were also evaluated and it has been concluded that the process was feasible, spontaneous, and endothermic in the temperature range of 5-40 C. © 2012 Springer Science+Business Media Dordrecht.Öğe Development of cloud point extraction preconcentration of cadmium and lead in solid samples using flame atomic absorption spectrometry(Desalination Publications, 2018) Bahadır Z.; Yazar M.; Tümay S.O.; Serencam H.; Bektaş H.; Duran C.2-[(6-Morpholin-4-ylpyridin-3-yl)amino]-N’-(4-oxo-3-phenyl-1,3thiazolidin-2-ylidene) acetohydrazide (MPAPTAH) was first used in a cloud point extraction procedure to determine the cadmium and lead ions in solid samples. Triton X-114 was used as a mixed micellar medium. The optimal extraction parameters (e.g. surfactant concentrations, amount of ligand, pH etc.) were evaluated. The optimum experimental conditions for Cd and Pb ions during the extraction procedure were carried out with 0.7 mg of MPAPTAH agent, 1.0 mL 0.2% (w/v) of the surfactant, a pH of 8.0. Under the best analytical parameters, the detection limit (LOD) for Cd(II) and Pb(II) ions were found to be 0.6 ?g L?1 and 1.91 ?g L?1, while the relative standard deviation (RSD) was taken as 2.78 and 2.86%, respectively. Preconcentration factor (PE) of 50 was obtained from using 50 mL of the sample volume for both ions. The accuracy of the method was tested through analysis of Pb2+ and Cd2+ in certified reference material (CRM Sandy Soil C). The interference effect of certain cations and anions were also investigated. The recoveries of the analyte ions were almost quantitative in the presence of all the interfering ions. Afterwards, the developed method was successfully applied to find lead and cadmium in real solid samples, including black tea, tobacco, and chili pepper. © 2018 Desalination Publications. All rights reserved.Öğe A novel method based on thermal conductivity for material identification in scrap industry: An experimental validation(Elsevier B.V., 2018) Cuce E.; Cuce P.M.; Guclu T.; Besir A.; Gokce E.; Serencam U.; Serencam H.Fast, accurate and reliable identification and sorting of materials is still a challenge in recycling sector. Scrap metals are often classified through density and colour, which cause notable financial burdens to the companies in most cases. Within the scope of this research, a novel method based on thermal conductivity is presented for material identification in scrap industry. The unit consists of a constant heat flux source and a cooling system, in which axial heat conduction is enabled and radial heat transfer is eliminated. For the steady-state conditions, temperature gradient across the sample metals is measured along with the constant heat flux value, and the thermal conductivity of the samples is determined via the Fourier's heat conduction law. Copper, brass and stainless steel samples are considered in this research to verify the accuracy of the results. For a reliable and scientific approach, three independent sets of experiments are conducted, and the results are evaluated in terms of accuracy and consistency. Experimental thermal conductivity values of the said samples are compared with the reported data in literature and a good accordance is achieved. Error in measurements is calculated to be 1.37, 3.31 and 4.46% for copper, brass and stainless steel sample, respectively which is acceptable. The tests are repeated with highly sensitive probes for aluminium sample, and the measurement error is calculated to be 0.56%. © 2018 Elsevier LtdÖğe Optimization of Adsorption Parameters for Ultra-Fine Calcite Using a Box-Behnken Experimental Design(De Gruyter, 2018) Uçurum M.; Özdemir A.; Teke C.; Serencam H.; Ipek M.Removal of heavy metals from wastewater is a significant issue because it prevents environmental-based concerns and impacts a large number of diseases and disorders. Many low-cost natural materials have been offered recently as possible precursors to commercial synthetic adsorbents. Ultra-fine calcite, one of these natural materials, has been investigated as a potential commercial adsorbent. Response surface designs are effective experimental techniques to investigate the heavy metal adsorption capacity of ultra-fine calcite. In the present study, one such response surface design, Box-Behnken, is used in order to optimize adsorption factors, such as pH level, initial metal concentration, stirring rate and adsorption time, and to determine the heavy metal capacity of this adsorbent. Our results show that the proposed methodology is an effective approach to optimizing the adsorption process and to maximize the heavy metal capacity. © 2018 Metin Uçurum et al., published by De Gruyter 2018.Öğe Production of enantiomerically enriched chiral carbinols using Weissella paramesenteroides as a novel whole cell biocatalyst(Taylor and Francis Ltd, 2019) Tozlu C.; Şahin E.; Serencam H.; Dertli E.In this study, four bacterial strains were tested for their ability to reduce acetophenones to its corresponding alcohol. Among these strains Weissella paramesenteroides N7 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for W. paramesenteroides N7 that resulted in high enantioselectivity and conversion rates for the bioreduction. The scale-up asymmetric reduction of 1-(4-methoxyphenyl) propan-1-one (1r) by W. paramesenteroides N7 gave (R)-1-(4-methoxyphenyl) propan-1-ol (2r) with 94% yield and >99% enantiomeric excess. This is the first report showing the synthesis of (R)-1-(4-methoxyphenyl) propan-1-ol (2r) in enantiopure form using a biocatalyst on a gram scale. The whole cell catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that W. paramesenteroides N7 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest as a promising and alternative green approach. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group.Öğe Selective separation, preconcentration and determination of Pd(II) ions in environmental samples by coprecipitation with a 1,2,4-triazole derivative(Chemical Society of Ethiopia, 2015) Ozdes D.; Duran C.; Serencam H.; Sahin D.; Gundogdu A.; Soylak M.A simple, sensitive, facile and low cost methodology, combined with flame atomic absorption spectrometry (FAAS), was employed to evaluate the selective separation and preconcentration of Pd(II) ions in environmental samples by using a triazole derivative as an organic coprecipitating agent without a carrier element. The developed method was systematically investigated in different set of experimental parameters that influence the quantitative recovery of Pd(II) ions. The accuracy of the method was tested by analyzing certified reference material and spike tests. The developed coprecipitation procedure has been applied to road dust, anodic slime, industrial electronic waste materials and water samples to determine their Pd(II) levels. © 2015 Chemical Society of EthiopiaÖğe Selective Separation, Preconcentration, and Determination of Au (III) Ions in Environmental Samples by Coprecipitation With a 1,2,4-Triazole Derivative(2013) Ozdes D.; Duran C.; Serencam H.; Şahin D.An effective, simple, lowcost, and accurate separation and preconcentration procedure which has minimal impact on the environment has been developed. It is based on the carrier element-free coprecipitation (CEFC) of Au(III)ions using N-benzyl-2-{[3-methyl-4-(2morpholine-4-ylethyl)-5-oxo-4,5-dihydro-1H-1,2, 4-triazole-1-yl] acetyl)hydrazinecarboxamide (BODAH) as an organic coprecipitant. Determination of the Au(IH) ion levels was performed by flame atomic absorption spectrometry (FAAS). The developed method provided a detection limit of 0.36 ?g L-1 and the relative standard deviation for Au(III)ions was found to be 5.1%. Spike tests and certified reference material analyses were performed to validate the method. The developed method was systematically investigated in different sets of experimental parameters that influence the quantitative recovery of the Au(III)ions. Based on these investigations, the optimum conditions for the determination of Au(III) ions at trace levels were established. The coprecipitation method was applied to anodic slime, gold ore, soil, and water samples to determine their Au(III)levels.Öğe Separation and pre-concentration of palladium(II) from environmental and industrial samples by formation of a derivative of 1,2,4-triazole complex on Amberlite XAD-2010 resin(2013) Serencam H.; Bulut V.N.; Tufekci M.; Gundogdu A.; Duran C.; Hamza S.; Soylak M.A simple separation/pre-concentration method was developed for extraction of Pd(II) in various environmental samples, based on its adsorption of 4-phenyl-5-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazole-3-yl)thio]methyl}-4H-1,2,4-triazole-3-thyol (PPTTMET) complex on Amberlite XAD-2010 resin in a mini column. The ligand has high affinity for Pd(II) among many other metals that are taken into consideration. The flame atomic absorption spectrometry is employed to determine the concentration of Pd(II). The optimum working conditions which were determined are as follows: 0.05 mol L-1 HNO3 as working medium, 1.0 mol L-1 HCI in acetone as elution solvent, 0.75 mg of PPTTMET amount and 750 mL of sample volume. The system was independent from the flow rates between 3.1 and 23.1 mL min-1. The Pd(II) adsorption capacity of Amberlite XAD-2010 resin was found to be 12.8 mg g-1 and the enrichment factor was calculated as 375. The method was successfully applied for the determination of Pd(II) in motorway dust samples, anodic sludge, gold ore, industrial electronic waste materials and various water samples. © 2013 Copyright Taylor and Francis Group, LLC.Öğe Simultaneous separation and preconcentration of Cd(II), Co(II), and Ni(II) ions in environmental samples by carrier element-free coprecipitation method prior to their flame atomic absorption spectrometric determination(Taylor and Francis Inc., 2015) Duran C.; Ozdes D.; Akcay H.T.; Serencam H.; Tufekci M.ABSTRACT: In the present study, Cd(II), Co(II), and Ni(II) ions were separated and preconcentrated via carrier element-free coprecipitation (CEFC) method by using an organic coprecipitating agent, 1,2-bis-(2-tosyl ethoxy) benzene (BTEB), prior to their flame atomic absorption spectrometric (FAAS) detections. The experimental conditions were optimized in terms of pH of the aqueous solution, BTEB amount, standing time, centrifugation rate and time, and sample volume. Under the optimum experimental conditions, the detection limits for Cd(II), Co(II), and Ni(II) ions were found to be 0.13, 0.67, and 0.46 ?g L?1, respectively, and the relative standard deviations for the analyte ions were found to be lower than 4.0%. The accuracy of the method was tested by analyzing certified reference material and spike tests. The method was applied to determine the levels of Cd(II), Co(II), and Ni(II) ions in sea and stream water, macaroni, red lentil, and cracked wheat samples. © 2013, © 2013 Balaban Desalination Publications. All rights reserved.Öğe Simultaneous separation and preconcentration of Ni(II) and Cu(II) ions by coprecipitation without any carrier element in some food and water samples(Blackwell Publishing Ltd, 2014) Duran C.; Tumay S.O.; Ozdes D.; Serencam H.; Bektas H.A simple and highly sensitive separation and preconcentration procedure, which has minimal impact on the environment, has been developed. The procedure is based on the carrier element-free coprecipitation of Ni(II) and Cu(II) ions by using 2-{4-[2-(1H-Indol-3-yl)ethyl]-3-(4-chlorobenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}-N?-(pyrrol-2-ylmethyliden)acetohydrazide (ICOTPA), as an organic coprecipitant. The levels of analyte ions were determined by flame atomic absorption spectrometry. The detection limits for Ni(II) and Cu(II) ions were found to be 0.27 and 0.58 ?g L-1, respectively, and the relative standard deviations for the analyte ions were lower than 4.0%. Spike tests and certified reference material analyses were performed to validate the method. The method was successfully applied for the determination of Ni(II) and Cu(II) ions levels in sea and stream water as liquid samples and red lentil and rice as solid samples. © 2013 Institute of Food Science and Technology.Öğe Solid phase extraction of Cd(ii) and pb(ii) ions by a new carbothioamide derivative(Sociedad Chilena de Quimica, 2013) Ozdes D.; Duran C.; Bayrak H.; Serencam H.; Basri Senturk H.An effective, simple, low cost and accurate sorption-spectrophotometric platform for the extractions and subsequent quantifications of Cd(II) and Pb(II) ions in food and environmental samples has been described in this dissertation. The separation and preconcentration of the analyte ions were accomplished by solid phase extraction method based on the adsorption of their N-(4-methylphenyl)-2-{[(4-phenyl-5-pyridin-4-yl-4H-1,2,4-triazol-3-yl)thio] acetyl} hydrazinecarbothioamide (MFPTAHK) complex on Amberlite XAD-8 resin in a mini column. The developed method was systematically investigated in different set of experimental parameters that influence the separation and preconcentration of Cd(II) and Pb(II) ions. The precision of the method was determined by reproducibility studies and expressed as relative standard deviations (RSD %) which were less than 4% for both analyte ions. The limits of detections (LODs) for Cd(II) and Pb(II) ions based on the three times the standard deviation of the blanks (N:10) were found to be 0. 31 ?g L-1 and 0. 86 ?g L-1, respectively. The developed SPE procedure was utilized for the simultaneous extraction and determinations of Cd(II) and Pb(II) ions levels in rice, cracked wheat and red lentil as food samples and various water samples.Öğe Synthesis and electrochemistry of metallophthalocyanines bearing {4-[(2E)-3-(3,4,5-trimethoxyphenyl)prop-2-enoyl]phenoxy} groups(2014) Acar I.; Arslan T.; Topçu S.; Aktaş A.; Şen S.; Serencam H.In this study, metallophthalocyanines 4, 5, 6 was carried out by the cyclotetramerization of 4-{3-[(2E)-3-(3,4,5-trimethoxyphenyl)prop-2-enoyl] phenoxy}phthalonitrile 3. The synthesis of metallo derivatives [Zn(II), Co(II), Cu(II)] of phthalocyanines obtained from corresponding phthalonitrile derivative and in the presence of the anhydrous divalent metal salts (Zn(CH 3COO)2, CoCl2 and CuCl2) was described. These phthalocyanines showed good solubility in organic solvents such as chloroform, tetrahydrofuran, DMSO and DMF. The newly synthesized Pcs were verified by IR, 1H NMR, 13C NMR, UV-vis and MS spectral data. The electrochemical properties of the zinc(II), copper(II) and cobalt(II) phthalocyanines were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The cobalt complex showed a metal based reduction process, while zinc phthalocyanines were giving ligand based electron transfer processes. © 2013 Elsevier B.V. All rights reserved.Öğe Toward a sustainable energy future in Turkey: An environmental perspective(Elsevier Ltd, 2013) Serencam H.; Serencam U.As long as the energy future of Turkey is concerned there is a consensus among all parties involved in the subject that a strong sustainability based on diverse range of renewable and variety of sources with efficient and fair use of energy is a must. The main criterion in this approach is to use energy with the least possible greenhouse gases and other harmful emissions. A shift in focus to meeting the needs of energy service sector will be immediately felt in the sustainable energy future in Turkey. Another important aspect of the sustainable energy future of Turkey is that all energy users, as more knowledgeable and active participants will be more involved in various stages of the process. However, Turkey has a long way to reach this vision, because of growing greenhouse emissions related to energy production and utilization of alternative energy is slow. Besides, the intensity of energy of the Turkish economy is decreasing slower than many other OECD countries. In addition, energy consumption per person in Turkey is far above the service needs, even for modern lifestyles. There are substantial obstacles on the way to a sustainable energy future of Turkey, such as various aspects of economic structure, a misdirected energy market process, and a lack of vision among the decision makers. © 2013 Elsevier Ltd.Öğe Whole cell application of Lactobacillus paracasei BD101 to produce enantiomerically pure (S)-cyclohexyl(phenyl)methanol(John Wiley and Sons Inc., 2019) Şahin E.; Serencam H.; Dertli E.In this study, a total of 10 bacterial strains were screened for their ability to reduce cyclohexyl(phenyl)methanone 1 to its corresponding alcohol. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for the reducing agent L paracasei BD101, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale asymmetric reduction of cyclohexyl(phenyl)methanone (1) by L paracasei BD101 gave (S)-cyclohexyl(phenyl)methanol (2) with 92% yield and >99% enantiomeric excess. The preparative scale study was carried out, and a total of 5.602 g of (S)-cyclohexyl(phenyl)methanol in high enantiomerically pure form (>99% enantiomeric excess) was produced. L paracasei BD101 has been shown to be an important biocatalyst in asymmetric reduction of bulky substrates. This study demonstrates the first example of the effective synthesis of (S)-cyclohexyl(phenyl)methanol by the L paracasei BD101 as a biocatalyst in preparative scale. © 2019 Wiley Periodicals, Inc.
