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Assessing effect of electrode configuration on the efficiency of electrokinetic remediation by sequential extraction analysis

Türer, Dilek | Genç, Ayten

Article | 2005 | JOURNAL OF HAZARDOUS MATERIALS119 ( 01.Mar ) , pp.167 - 174

The electroremediation experiments were conducted on artificially polluted soils by introducing a single metallic contaminant (Pb, Zn and Cu) and multiple metallic contaminants (Pb + Zn + Cu). Based on sequential extraction results, it was observed that the removal efficiencies of lead, zinc and copper vary depending on types of contamination. When the soil was contaminated only by lead, the removal efficiency was found to be 48%. However, the removal efficiency of lead decreased to 32% when the soil was contaminated by the combination of lead, zinc and copper. Similar results were observed for zinc and copper. The corresponding rem . . .oval efficiency values for zinc and copper were 92% and 37%, and 34% and 31%, respectively. Effects of electrode geometry on the removal efficiency of metals were investigated by constructing a multiple anode arrangement. In this arrangement, the electrokinetic unit consists of three cylinders, which lie one inside the other, and the soil was placed in the middle cylinder. The central cylinder was the cathode well and the outer cylinder was the anode well, where eight identical anode electrodes were placed in octagonal with respect to the cathode electrode. By using this electrode arrangement in removal of metals from the soil contaminated with the combination of three metals (Pb + Zn + Cu), the removal efficiencies of lead, zinc and copper were found to be 29%, 18% and 18%, respectively. As it can be seen, these numerical values are much lower than the values that were obtained when the traditional two-plate electrode arrangement used in the electroremediation experiments (32%, 37% and 31%). (c) 2004 Elsevier B.V. All rights reserved Daha fazlası Daha az

Treatment of emulsified oils by electrocoagulation: Pulsed voltage applications

Genç, Ayten | Bakırcı, Büşra

Article | 2015 | Water Science and Technology71 ( 8 ) , pp.1196 - 1202

The effect of pulsed voltage application on energy consumption during electrocoagulation was investigated. Three voltage profiles having the same arithmetic average with respect to time were applied to the electrodes. The specific energy consumption for these profiles were evaluated and analyzed together with oil removal efficiencies. The effects of applied voltages, electrode materials, electrode configurations, and pH on oil removal efficiency were determined. Electrocoagulation experiments were performed by using synthetic and real wastewater samples. The pulsed voltages saved energy during the electrocoagulation process. In cont . . .inuous operation, energy saving was as high as 48%. Aluminum electrodes used for the treatment of emulsified oils resulted in higher oil removal efficiencies in comparison with stainless steel and iron electrodes. When the electrodes gap was less than 1 cm, higher oil removal efficiencies were obtained. The highest oil removal efficiencies were 95% and 35% for the batch and continuous operating modes, respectively. © IWA Publishing 2015 Daha fazlası Daha az

Comparison of separation processes for the treatment of emulsified oils from water

Candan, Köse | Genç, Ayten

Proceedings | 2015 | WATER RESOURCES MANAGEMENT VIII196 , pp.505 - 512

In this study, vacuum filtration, coagulation-flocculation, electrocoagulation and centrifugation were applied to separate emulsified oils from water. Two different types of cutting oils (BOR and EAL) were used in the preparation of oil emulsions. BOR has smaller oil droplets than EAL when they are mixed by water. It was not possible to separate BOR from water by microfiltration but 81.7% removal efficiency was obtained for EAL. Alum and ferric chloride were used as coagulants and optimum coagulant dosages, mixing time and pH were determined by performing jar tests. When alum was used as the coagulant, the removal efficiencies for B . . .OR and EAL were 90% and 98%, respectively. In the case of ferric chloride, 98% oil removal was obtained for both emulsions. However, the optimum ferric chloride dosages were much higher than alum. The optimum alum and ferric chloride dosages for BOR emulsion were 0.83 g/L and 6 mg/L, respectively. In the case of EAL emulsion, the corresponding amounts were 4 mg/L and 8 mg/L. The flocculation time was determined around 45 minutes. In order to obtain 98% BOR removal, the emulsion was centrifuged at an angular velocity of 3000 rpm after the coagulation-flocculation process. On the other hand, when BOR and EAL were separated by electrocoagulation, 95% removal rates can be obtained for both oils applying 40 V difference to the aluminum electrodes for 35 minutes. According to the removal efficiencies obtained from the experiments and the preliminary cost analysis it can be concluded that the best method for separating emulsified oils from waters is the electrocoagulation Daha fazlası Daha az

Experimental studies on the effect of electrode configuration in electrofiltration

Genç, Ayten | Tosun, İbrahim

Article | 2002 | Separation Science and Technology37 ( 13 ) , pp.3053 - 3064

Results from the electrofiltration of anatase (TiO2) particles in a water suspension and using three different electrode configurations are presented. The three electrode configurations studied were spot, foil, and mesh. For the first two configurations, the electric field was perpendicular to the direction of flow while for the mesh configuration it was opposite to the direction of flow. The percent gain volume filtrate and power consumption were measured for each electrode configuration. For a given percent gain volume filtrate, it was observed that the foil electrode configuration consumes the least power.

Membrane potentials for linearly varying fixed charges

Genç, Ayten

Article | 2009 | Turkish Journal of Engineering and Environmental Sciences33 ( 1 ) , pp.73 - 81

The membrane potentials for asymmetric membranes where fixed charges varied linearly with position were evaluated from the numerical solutions of Nernst-Planck flux and Donnan potential equations. The evaluated membrane potentials were compared with the results obtained from the conventional TMS theory where the fixed charge concentration in the membrane was assumed to be uniform. In the comparison, the number of fixed charges was kept constant by defining an average for the fixed charge concentration. The numerical results showed that the membrane potential increased in magnitude when the distributions of fixed charges at the membr . . .ane-solution interfaces were unequal. In addition, the deviation from TMS theory increased more as the charge difference at the interfaces increased. © TÜBİTAK Daha fazlası Daha az

Analysis of the electrofiltration mechanism based on multiphase filtration theory

Genç, Ayten | Tosun, İsmail

Article | 2004 | Chemical Engineering Communications191 ( 1 ) , pp.125 - 136

A mathematical model based on multiphase filtration theory is developed to describe the electrofiltration process. The model takes both electrophoretic and electroosmotic effects into account. The electrophoretic migration velocity of solid particles is predicted from the model using the filtrate volume time data obtained from electrofiltration experiments.

Electrokinetic removal of manganese from river sediment

Genç, Ayten | Chase, George | Foos, Annabelle

Article | 2009 | Water, Air, and Soil Pollution197 ( 01.Apr ) , pp.131 - 141

Manganese was removed from naturally polluted river sediment by applying an electrokinetic remediation technique. The sediment was alkaline and had 20% clay, which was mainly illite. The electrokinetic remediation experiments were performed by controlling pHs in the electrode cells and reverse electroosmotic flows were observed, i.e., water moved from cathode towards anode. Manganese accumulated in areas closer to cathode, however, other metals, such as copper, zinc and lead were mostly observed in the middle section of the sediment. As a result of reverse electroosmotic flow, the removal efficiencies of metals were low and the high . . .est removal efficiencies of manganese, copper and lead, were evaluated as 18%, 20% and 12%, respectively. Almost no removal of zinc was observed in all electrokinetic remediation experiments. © 2008 Springer Science+Business Media B.V Daha fazlası Daha az

Destabilization and treatment of emulsified oils in wastewaters by electrocoagulation

Genç, Ayten | Bakırcı, Büşra

Article | 2016 | Water Environment Research88 ( 11 ) , pp.2008 - 2014

In this study, the optimum operating conditions for the treatment of emulsified oils by electrocoagulation were determined depending on droplet stability analysis. Zeta potential measurements were used as the indication of oil droplet charges. In addition, the effects of pH and ionic conductivity on the droplet sizes and surface charges were investigated. The studied emulsified oil droplet sizes were more sensitive to changes in pH rather than salt concentration. The droplets became larger and unstable in alkaline conditions. As the initial pH of wastewaters increased, the oil removal efficiency increased during the electrocoagulati . . .on experiments as well. The use of iron or aluminum electrodes resulted in higher removal efficiencies in comparison to stainless steel electrodes. In addition, the energy consumption for aluminum electrodes was much lower than iron electrodes. To obtain 98% oil removal efficiency, distance between the electrodes was recommended to be less than or equal to 1 cm. © 2016, Water Environment Federation. All rights reserved Daha fazlası Daha az

Sorption of acid dyes from aqueous solution by using non-ground ash and slag

Genç, Ayten | Oğuz, Aşkın

Article | 2010 | Desalination264 ( 01.Feb ) , pp.78 - 83

The sorption of two acid dyes (Acid Yellow 99 and Acid Red 183) into locally available industrial waste materials, namely, Granulated Blast Furnace Slag (GBFS) and Furnace Bottom Ash (FBA), has been investigated by performing batch equilibrium experiments with pH, ionic conductivity, initial dye concentration and temperature as variables. The kinetic sorption data indicated that the sorption capacity of GBFS for these dyes was almost zero. On the other hand, the color removal efficiency for FBA could reach 50% depending on the initial dye concentration. It was also found that the kinetics of sorption of Acid Yellow 99 and Acid Red 1 . . .83 onto the surface of FBA at different operating conditions were best described by the Elovich kinetic model. In addition, the adsorption equilibrium data were analyzed using various adsorption isotherm models and the results have shown that the sorption behaviors of the studied dyes could be best described by the Langmuir model. © 2010 Elsevier B.V Daha fazlası Daha az

Transport of Lead (Pb2+) Ions through silty-clayey soils under acidic conditions

Genç, Ayten | Ulupınar, Elif

Article | 2010 | Transport in Porous Media84 ( 3 ) , pp.699 - 709

This study aimed to identify effects of pH on the transport of Pb2+ ions through a saturated silty-clayey soil layer by using advection-dispersion equation (ADE). The predictive accuracy of the solution of ADE depends on the proper determination of the retardation by adsorption and, therefore, the adsorption mechanism of lead onto silty-clayey soil was investigated first by performing batch equilibrium experiments. These results showed that the sorption mechanism of lead onto silty-clayey soil depended on pH and could be best described by the Langmuir isotherm. Based on the results of the sequential experiments, it was also conclude . . .d that the pH dependent charges in silty-clayey soil were mainly associated with the surfaces of carbonates and the specific adsorption of lead ions. The numerical solutions of the combined form of ADE with the Langmuir isotherm indicated that the migration profiles of lead in silty-clayey soil were a strong function of the parameters of the Langmuir isotherm rather than the infiltration velocity. © 2010 Springer Science+Business Media B.V Daha fazlası Daha az

Prediction of the bottom ash formed in a coal-fired power plant using artificial neural networks

Bekat, Tuğçe | Erdoğan, Muharrem | İnal, Fikret | Genç, Ayten

Article | 2012 | Energy45 ( 1 ) , pp.882 - 887

The amount of bottom ash formed in a pulverized coal-fired power plant was predicted by artificial neural network modeling using one-year operating data of the plant and the properties of the coals processed. The model output was defined as the ratio of amount of bottom ash produced to amount of coal burned (Bottom ash/Coal burned). The input parameters were the moisture contents, ash contents and lower heating values of the coals. The total 653 data were divided into two groups for the training (90% of the data) and the testing (10% of the data) of the network. A three-layer, feed-forward type network architecture with back-propaga . . .tion learning was used in the modeling study. The activation function was sigmoid function. The best prediction performance was obtained for a one hidden layer network with 29 neurons. The learning rate and the tolerance value were 0.2 and 0.05, respectively. R2 (coefficient of determination) values between the actual (Bottom ash/Coal burned) ratios and the model predictions were 0.988 for the training set and 0.984 for the testing set. In addition, the sensitivity analysis indicated that the ash content of coals was the most effective parameter for the prediction of the ratio of bottom ash to coal burned. © 2012 Elsevier Ltd Daha fazlası Daha az

Effects of coal properties on the production rate of combustion solid residue

Durgun D. | Genç, Ayten

Article | 2009 | Energy34 ( 11 ) , pp.1976 - 1979

The production rates of furnace bottom ash in a pulverized coal-fired power plant were monitored for a two-year period and its variations with respect to coal properties were analyzed. The power plant was originally designed to fire the coal sludge generated from a washing process; however, the coal sludge and its mixture with low-rank bituminous coal have been started to be used as the main fuel with time. The results of the hardgrove grindability measurements have shown that the grinding properties of sludge or its mixtures could not be predicted based on proximate analysis (moisture, ash, carbon and volatile contents); it could o . . .nly be determined by experiments. The production rate of bottom ash in this particular power plant remained relatively insensitive to the high ash and moisture contents and could be estimated almost only by knowing the calorific value of the source coal. The evaluated dependency was linear. © 2009 Elsevier Ltd. All rights reserved Daha fazlası Daha az

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