Yazarlar
- Duran, Celal(38)
- Ozdes, Duygu(33)
- Kankal, Murat(13)
- Şan, Murat(12)
- Gundogdu, Ali(11)
- Nacar, Sinan(10)
- Ozeken, Sengul Tugba(7)
- Soylak, Mustafa(7)
- Alemdag, Selcuk(6)
- Bulut, Volkan Numan(6)
- Kıranşan, Murat(6)
- Serencam, Huseyin(6)
- Akar, Bülent(5)
- Baltaci, Cemalettin(5)
- Gücer, Mehmet Ali(5)
- Tufekci, Mehmet(5)
- Akaryali, Enver(4)
- Bozbeyoglu, Pinar(4)
- Camoglu, Aslihan Yilmaz(4)
- Elvan, Hamide(4)
- Imamoglu, Mustafa(4)
- Seker, Serdal(4)
- Akpinar, A.(3)
- Akçay, Fatma(3)
- Alemdağ, Selçuk(3)
- Başoğlu, Aysel(3)
- Günen, Mehmet Akif(3)
- Kaygusuz, K.(3)
- Okkan, Umut(3)
- Senturk, Hasan Basri(3)
- Turfan, Fatma Asya(3)
- Vural, Alaaddin(3)
- Yagmur, Nur(3)
- Yıldız, Mehmet Berkant(3)
- Şibil, Rahim(3)
- Aras, Egemen(2)
- Ayas, Mustafa Sinasi(2)
- Ayas, Selen(2)
- Bahadir, Zekeriyya(2)
- Barinova, Sophia(2)
Yayınlar
- MakaleYalnız künye2013Determination of Pb(II), Zn(II), Cd(II), and Co(II) ions by flame atomic absorption spectrometry in food and water samples after preconcentration by coprecipitation with Mo(VI)-diethyldithiocarbamate
Tufekci, Mehmet; Bulut, Volkan Numan; Elvan, Hamide; Ozdes, Duygu; Soylak, Mustafa; Duran, Celal
A new, simple, and rapid separation and preconcentration procedure, for determination of Pb(II), Cd(II), Zn(II), and Co(II) ions in environmental real samples, has been developed. The method is based on the combination of coprecipitation of analyte ions by the aid of the Mo(VI)-diethyldithiocarbamate- (Mo(VI)-DDTC) precipitate and flame atomic absorption spectrometric determinations. The effects of experimental conditions like pH of the aqueous solution, amounts of DDTC and Mo(VI), standing time, centrifugation rate and time, sample volume, etc. and also the influences of some foreign ions were investigated in detail on the quantitative recoveries of the analyte ions. The preconcentration factors were found to be 150 for Pb(II), Zn(II) and Co(II), and 200 for Cd(II) ions. The detection limits were in the range of 0.1-2.2 μg L-1 while the relative standard deviations were found to be lower than 5 % for the studied analyte ions. The accuracy of the method was checked by spiked/recovery tests and the analysis of certified reference material (CRM TMDW-500 Drinking Water). The procedure was successfully applied to seawater and stream water as liquid samples and baby food and dried eggplant as solid samples in order to determine the levels of Pb(II), Cd(II), Zn(II), and Co(II) ions.
- MakaleYalnız künye2013Cadmium and nickel determinations in some food and water samples by the combination of carrier element-free coprecipitation and flame atomic absorption spectrometry
Bahadir, Zekeriyya; Ozdes, Duygu; Bulut, Volkan Numan; Duran, Celal; Elvan, Hamide; Bektas, Hakan; Soylak, Mustafa
A procedure for separation and enrichment of Cd(II) and Ni(II) ions based upon carrier element-free coprecipitation by using an organic coprecipitant, 2-{4-[2-(1H-Indol-3-yl)ethyl]-3-(4-methylbenzyl)-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-yl}-N-(3-fluoro-phenylmethyliden) acetohydrazide, prior to their flame atomic absorption spectrometric detections has been developed. The effects of varied experimental conditions on the performance of the developed method such as pH, sample volume, amount of coprecipitating agent, etc. were evaluated in detail on the recovery of analyte ions, and the influences of some anions and cations were investigated. The limits of detection for Cd(II) and Ni(II) ions based on three times the standard deviation of the blanks (N: 10) were obtained as 0.70 g L-1 and 1.21 g L-1, respectively. The accuracy of the method was tested by analyzing a certified reference material and by spike tests. The method was applied to determine the levels of cadmium and nickel in stream and sea water, rice, red lentil, and wheat samples.
- Derleme MakaleYalnız künye2012RETRACTED: Regional sustainable water and energy development projects: A case of Southeastern Anatolia Project (GAP) in Turkey (Retracted article. See vol. 83, pg. 173, 2018)
Akpinar, A.; Kaygusuz, K.
Southeastern Anatolia Project (GAP) region in Turkey is rich in water for irrigation and hydroelectric power. The Euphrates and Tigris Rivers represent over 28% of the nation's water supply by rivers, and the economically irrigable areas in the region make up 20% of those for the entry country. Turkey has a total gross hydropower potential of 433 GWh/yr, but only 125 GWh/yr of the total hydroelectric potential of Turkey can be economically used. By the construction of new hydropower plants, 36% of the economically usable potential of the country would be tapped. The GAP region has a 22% share of the country's total hydroelectric potential, with plans for 22 dams and 19 hydroelectric power plants. Once completed, 27 billion kWh of electricity will be generated annually. (C) 2011 Elsevier Ltd. All rights reserved.
- MakaleAçık Erişim2012Dehydrated hazelnut husk carbon: A novel sorbent for removal of Ni(II) ions from aqueous solution
Sivrikaya, Sezen; Albayrak, Sinem; Imamoglu, Mustafa; Gundogdu, Ali; Duran, Celal; Yildiz, Hulya
The present study has been performed to examine the adsorption ability of novel sorbent dehydrated hazelnut husk carbon (DHHC) towards Ni(II) ions from aqueous solution using the batch adsorption technique. The effective factors such as initial pH of the aqueous solution, contact time, initial Ni(II) concentration, adsorbent dosage, and temperature were investigated. The studies were also conducted to understand the effect of some co-existing ions which may be present in aqueous solutions. DHHC showed good adsorption potential for Ni(II) ions. The optimum initial pH value was selected as 5.0. The experimental data fitted well to the Langmuir adsorption isotherm model. Among the kinetic models tested for the adsorption of Ni(II), the pseudo-second-order model showed a good fit of the kinetic data. The thermodynamic parameters including the Gibbs free energy (ΔG), enthalpy (ΔH), and entropy (ΔS) changes indicated that the adsorption of Ni(II) ions onto DHHC was feasible, spontaneous, and exothermic in the temperature range of 25-55°C. The results of this study showed the effectiveness and feasibility of DHHC for the removal of Ni(II) ions from aqueous solution.
- MakaleAçık Erişim2012Assessment of permeability and injection depth at the Atasu dam site (Turkey) based on experimental and numerical analyses
Gurocak, Zulfu; Alemdag, Selcuk
This study was performed in order to evaluate the permeability of the basalts and pyroclastics and the maximum depth of grout injection at the Atasu dam site, Turkey, using the equations of Kiraly and Hoek and Bray based on values obtained from Lugeon tests. In order to evaluate maximum discharge values and depth of injection, seepage analyses were performed using the finite element technique for each 10 m up to 100 m. The results indicate that to establish an impermeable zone at the dam site, the depth of injection should be taken as 50 m for the left and right slopes and 40 m for the river bed.
- MakaleAçık Erişim2012Optimization of a new cloud point extraction procedure for the selective determination of trace amounts of total iron in some environmental samples
Duran, Celal; Özdeş, Duygu; Çelenk Kaya, Elif; Kantekin, Halit; Bulut, Volkan Numan; Tüfekçi, Mehmet
A new, simple, and rapid cloud point extraction (CPE) procedure system, combined with flame atomic absorption spectrometry (FAAS), was developed for selective separation, preconcentration, and determination of trace amounts of total iron in some environmental samples. The complexing agent, N,N-(2,2 - (ethane-1,2-diylbis(oxy))bis(ethane-2,1-diyl))bis(2-chloroacetamide) (EDBOCA), is selective at pH 5.0 for only Fe(II) and Fe(III) ions in the presence of Cu(II), Pb(II), Cd(II), Mn(II), Co(II), Cr(III), Cr(VI), Ni(II), Zn(II), Al(III), Mo(VI), Pd(II), Pt(IV), Au(III), and V(V) ions. The procedure is based on the complexation of Fe(III) ions with EDBOCA reagent in the presence of Triton X-114 (TX-114) as a non-ionic surfactant. The optimum conditions for the CPE of Fe(III) ions were investigated with respect to several experimental parameters such as pH of the solution, TX-114 and EDBOCA concentrations, incubation time and temperature, and centrifugation rate and time. The detection limit for Fe(III) ions based on the 3 times the standard deviation of the blanks (N:10) was found to be 1.22 μg L ?1 , while the relative standard deviation (RSD) was 4.2%. Environment Canada TM-25.3 and CRM-SA-C Sandy Soil C, as certified reference materials, were used, and spike tests were applied to validate the method. The method was applied to some real environmental samples to evaluate their total iron levels.
- MakaleYalnız künye2012Adsorption of Phenol from Aqueous Solution on a Low-Cost Activated Carbon Produced from Tea Industry Waste: Equilibrium, Kinetic, and Thermodynamic Study
Gundogdu, Ali; Duran, Celal; Senturk, H. Basri; Soylak, Mustafa; Ozdes, Duygu; Serencam, Huseyin; Imamoglu, Mustafa
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.
- Derleme MakaleYalnız künye2011Development of hydropower energy in Turkey: The case of Coruh river basin
Akpinar, Adem; Kömürcü, Murat Ihsan; Kankal, Murat
The main objective in doing the present study is to investigate the sustainable development of hydropower plants in the Coruh river basin of Turkey, which is least problem river of Turkey in respect to international cooperation as compared with Turkey's other trans-boundary waters. Initial studies concerning the hydropower production potential in Coruh basin had been carried out by Turkish authorities in the late 1960s. Total installed power capacity and annual average energy generation of 37 dams and run of river (without storage) hydropower plants developed at various project stages by The Electrical Power Resources Survey and Development Administration (EiE) in Coruh basin are 3132.70 MW and 10.55 TWh/yr, respectively. Today, this generation value corresponds 6.45% of Turkey's energy consumption in 2006 while it meets 6.3% of total electricity energy production of Turkey which is equal to 167.9 TINh/yr in 2006. Besides, this potential developed at various project stages in Coruh basin will provide 24.1% of Turkey's hydroelectric energy generation being equal to 43.8 TWh/yr in 2006. (C) 2010 Elsevier Ltd. All rights reserved.
- MakaleYalnız künye2011Preconcentration of Cd(II) and Cu(II) ions by coprecipitation without any carrier element in some food and water samples
Duran, Celal; Ozdes, Duygu; Sahin, Deniz; Bulut, Volkan Numan; Gundogdu, Ali; Soylak, Mustafa
A simple, rapid, sensitive and environmentally friendly separation and preconcentration procedure, based on the carrier element free coprecipitation (CEFC) of Cu(II) and Cd(II) ions by using an organic coprecipitant, 2-{[4-(4-fluorophenyl)-5-sulphanyl-4H-1,2,4-triazol-3-yl]methyl}-4-{[(4-fluorophenyl) methylene]amino}-5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazol-3-one (MEFMAT) was developed. The analyte ions were determined by flame atomic absorption spectrometric (FAAS) determinations. The optimum conditions for the coprecipitation process were investigated on several commonly tested experimental parameters such as pH of the solution, amount of MEFMAT, sample volume, standing time, centrifugation rate and time. The influences of some anions, cations and transition metals on the recoveries of analyte ions were also investigated, and no considerable interference was observed. The preconcentration factor was found to be 50. The detection limits for Cu(II) and Cd(II) ions based on the three times the standard deviation of the blanks (N:10) were found to be 1.49 and 0.45μgL-1, respectively. The relative standard deviations were found to be lower than 3.5% for both analyte ions. The method was validated by analyzing two certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) and spike tests. The procedure was successfully applied to sea water and stream water as liquid samples and tobacco, hazelnut and black tea as solid samples.
- MakaleYalnız künye2011Investigation of water length effects on the modal behavior of a prototype arch dam using operational and analytical modal analyses
Sevim, Bariş; Bayraktar, Alemdar; Can Altunişik, Ahmet
This study determines the water length effects on the modal behavior of a prototype arch dam using Operational and Analytical Modal Analyses. Achievement of this purpose involves construction of a prototype arch dam-reservoir- foundation model under laboratory conditions. In the model, reservoir length was taken to be as much as three times the dam height. To determine the experimental dynamic characteristics of the arch dam using Operational Modal Analysis, ambient vibration tests were implemented for empty reservoir and three different reservoir water lengths. In the ambient vibration tests, the dam was vibrated by natural excitations provided from small impact effects and the response signals were measured using sensitive accelerometers. Operational Modal Analysis software process signals collected from the ambient vibration tests, and Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques estimated modal parameters of the dams. To validate the experimental results, 3D finite element model of the prototype arch dam was modeled by ANSYS software for empty reservoir and three different reservoir water lengths, and dynamic characteristics of each model were determined analytically. At the end of the study, experimentally and analytically identified dynamic characteristics compared to each other. Also, changes on the natural frequencies along to water length are plotted as graphs. Results suggest that reservoir water complicates the modal behavior of the arch dam significantly.
- MakaleYalnız künye2010Exergetic performance analysis of a recirculating aquaculture system
Kucuk, Haydar; Midilli, Adnan; Özdemir, Atilla; Çakmak, Eyüp; Dincer, Ibrahim
This paper examines exergetic aspects of a Recirculation Aquaculture System (RAS) for Black Sea trout (Salmo trutta labrax) fingerling rearing at the Trabzon Central Fisheries Research Institute, Turkey. In its thermodynamic analysis, each component of the RAS is treated as a steady-state steady flow system and its exergetic efficiencies are studied. In addition, the following parameters are measured and recorded in experiments: the mass flow rates, inlet and outlet temperatures and of the system components, surrounding temperatures, and electrical work utilized by the components in the RAS. Based on these experimental data, inlet and outlet exergy values, exergy losses, and exergetic efficiencies of each component in the system are determined to assess their performance. Moreover, the overall system exergy efficiency is determined. The results show that exergy efficiencies of the system components are highly affected by varying input exergy flows as a function of the surrounding temperature and chiller's operating period.
- MakaleAçık Erişim2009Water quality modeling and dissolved oxygen balance in streams: A point source Streeter-Phelps application in the case of the Harsit stream
Nas, S. Serkan; Nas, Evin
The Harsit Stream flowing into the Black Sea is an important watershed in the northeastern part of Turkey. The monthly averages of dissolved oxygen, carbonaceous biochemical oxygen demand, temperature, pH, total suspended solids, total phosphorus and total nitrogen were obtained for the water samples taken from the Tekke, Akcakale and Haciemin sites of the Harsit Stream. Water quality parameters were analyzed and evaluated according to the WHO standards and the Turkish Water Pollution Control Regulation. Initially, the variations in the dissolved oxygen profile were determined from dissolved oxygen, temperature and carbonaceous biochemical oxygen demand measurements by using the point source Streeter-Phelps equation. Critical dissolved oxygen deficit values were calculated for the monthly average from January-December 2005, which are below the limit value (4 mg L-1) excluding April (7.26 mg L-1) and May (5.98 mg L-1) in the Harsit Stream, resulting in it having second class water quality in terms of dissolved oxygen concentration, temperature, pH and biochemical oxygen demand. It is also seen that the minimum dissolved oxygen limit value (8 mg L-1), which is a desired quantity for drinking water, is under the limit value for all months in the case of the water mixture. In particular, during the summer months, the consumption speed of oxygen is greater than the production speed of oxygen with increasing temperature and decreasing discharge, and negative values (anoxia) of dissolved oxygen sag are seen. These situations call for significant precautions and treatment criteria.
