Kahraman, Bekir Fatih | Altın, Ahmet | Altın, Süreyya | Demirel-Bayık, Gülçin

Article | 2017 | Soil and Sediment Contamination26 ( 5 ) , pp.486 - 500

Nutrient enhancement of bioremediation with nitrogen, namely biostimulation, increases process performance. Selection of a proper nitrogen source is critical for bioremediation applications. In this study, the effects of different nitrogen sources on biodegradation of C10–C25 n-alkane compounds in diesel fuel-spiked soil were revealed, and the most appropriate nitrogen source for biodegradation of semi- and non-volatile n-alkanes was investigated. Bioremediation of diesel fuel contaminated soil was monitored in lab-scale reactors for 15 days. Ammonium sulfate, potassium nitrate and urea were used as nitrogen sources. Carbon dioxide . . .and oxygen levels in the reactors were recorded to monitor microbiological activity. Contaminant removal process was investigated by pH, heterotrophic plate count, total petroleum hydrocarbons (TPH) and C10–C25 n-alkane analyses. First-order kinetic constants were calculated via respirometric and contaminant concentration data. According to total C10–C25 n-alkane removal levels and degradation rate constants, ammonium sulfate addition resulted in the most efficient contaminant removal followed by potassium nitrate and urea. Simultaneous degradation of individual n-alkanes was observed for all of the nitrogen sources. Urea addition changed the distribution of individual n-alkane concentrations relative to the pre-experimental concentrations. Nitrogen source type had no differential effect on degradation rates of semi- (C10–C16) and non-volatile (C17–C25) fractions. © 2017 Taylor & Francis Group, LLC Daha fazlası Daha az

Altın, Süreyya | Öztekin, Elif | Altın, Ahmet

Article | 2017 | Korean Journal of Chemical Engineering34 ( 8 ) , pp.2218 - 2224

Electrodialysis (ED) and electrodialysis reversal (EDR) processes have been often used for separation of ions in dilute solutions. In this study, the performance of ED and EDR processes has been examined in the removal of copper from the dilute solutions. First, applied voltage, initial concentration, flow rate, type of electrolyte and the effect of concentration were determined for both processes. Then, separation efficiency, current efficiency, energy requirement and material flux of the processes were calculated, and the performances of the processes were compared. The separation efficiency and energy consumption of EDR process w . . .ere higher compared to ED process under equal operating conditions. Also, the current efficiency (39.58%) of EDR process was lower than the current efficiency (67.46%) of ED process. It can be said that the ED process is more suitable in terms of energy consumption for separation in the low flow rate and concentration. © 2017, Korean Institute of Chemical Engineers, Seoul, Korea Daha fazlası Daha az

Altın, Süreyya | Altın, Ahmet | Kahraman, Bekir Fatih | Alemdar, Sonay | Alaydın, Elif

Article | 2015 | Fresenius Environmental Bulletin24 ( 1B ) , pp.302 - 310

In this study, the utilization of dried activated sludge for removal of Cd2+ from aqueous solution in a batch system was investigated. Initial pH, biosorbent dosage, contact time, and initial metal concentration parameters were selected to determine optimal process conditions. The bi-osorption mechanism was examined by SEM, FTIR and EDX results. The optimum conditions for Cd2+ biosorption were found to be 6.0, 120 min., 1.2 g. L-1 and 80 mg. L-1, respectively for initial pH, contact time, biosorbent dosage and initial Cd2+ concentration. Langmuir and Freundlich isotherms were used to model the biosorption equilibrium data, and it wa . . .s determined that the system followed the Langmuir isotherm, and the sorption capacity of the biosorbent was found to be 15.43 mg.g-1. Biosorption followed a pseudo-second-order rate model. Two main mechanisms of Cd2+ biosorption onto the dried activated sludge were adsorption to the C-H bonds and ion exchange with Na+, K+ and Ca2+ ions Daha fazlası Daha az

Altın, Süreyya | Gemici, Betül Tuba

Article | 2017 | FRESENIUS ENVIRONMENTAL BULLETIN26 ( 11 ) , pp.6438 - 6446

In this study, the performances of supported liquid membrane (SLM) and electrodialysis (ED) processes have been compared for separation of Cd (II) ions from aqueous solution. The operating parameters for the both laboratory-scale prepared processes have been optimized. The influence of operating parameters on the process performance has been established. Then separation efficiency, initial concentration and flux values of the processes optimized have been compared. The optimum initial concentration of the SLM process (75 mg/L) is higher than the optimum initial concentration of the ED process (5 mg/L). The separation efficiency of t . . .he ED process (85%) is higher than the SLM process (58%). As a conclusion, it has been established that the both processes deliver a significant separation performance for separating Cd(II) ions, however, ED Process is more efficient than SLM process for low initial concentration. SLM process is suitable for relatively high concentration and chemical selectivity Daha fazlası Daha az

Altın, Süreyya | Peker, İbrahim | Demircioğlu, Nesli

Article | 2009 | Polish Journal of Chemistry83 ( 2 ) , pp.275 - 283

In this study, the effects of the different membrane diluents, carriers and variations in the concentrations of the carriers on the sodium ion transport were examined in bulk liquid membrane systems. The kinetic analysis of the sodium ion transport in the liquid membrane was performed through the implementation of two consecutive kinetic equations of first order irreversible reactions and the relevant kinetic parameters (k1, k2a, k2a, Rmax, tmax,) were determined. Toluene, n-hexane, 1-octanol, chloroform and dichloromethane were used as membrane diluents, while 18crown6 (18C6), dicyclohexyl 18crown6 (DC18C6) and dibenzo 18crown6 (DB . . .18C6) were used as carriers. The results reveal that the best sodium ion transport was realized when toluene-dichloromethane (90%-10%) was used as the membrane, and 1.10-3 M DB18C6 was used as the carrier Daha fazlası Daha az

Altın, Ahmet | Altın, Süreyya | Yıldırım, Ömür

Article | 2017 | Journal of Environmental Protection and Ecology18 ( 2 ) , pp.652 - 661

The present study aims to examine the electro-Fenton/electro-coagulation (EF/EC) process for the treatment of wastewater generated from Kraft pulp and paper mills. As a result of the experimental studies, the optimum operating parameters of the EF/EC process have been identified as follows: current = 1.0 A, initial H2O2 concentration = 1000 mg/l and initial pH 2.5. It has been established that, under these conditions, the COD could be removed at 91.7%. It has been understood that the sludge produced from the EF/EC reactor possesses fairly good sedimentation characteristics and is significantly affected by the operating parameters. I . . .t has been established that the best sedimentation characteristics can be achieved when the current is ? 1.0 A, the initial pH value is between 2.3 and 3.2, and the initial H2O2 concentration is between 400 and 1800 mg/l Daha fazlası Daha az

Altın, Süreyya | Özgüven, Melih

Article | 2011 | Fresenius Environmental Bulletin20 ( 3 ) , pp.631 - 638

This study analyzed the zinc transport in supported liquid membrane (SLM) systems in which different anionic (Aliquat336) and cationic (D2EHPA) carriers, different solvents (kerosene and toluene) and different feed (deionized water and HCl) / stripping solutions (H3PO4, HCl and H 2SO4) were used. The results were modeled according to steady state (Fick's first law) and non-steady state kinetics approaches and the concordance of the models was discussed. It was observed from the experimental studies that 80.4% zinc transport could be achieved when deionized water was used as feed solution, kerosene/ D2EHPA (0.01 M) as membrane soluti . . .on combination and H3PO4(0.5 M) as stripping solution. Whilst the zinc transport efficiency was found to be 86.5% when HCl (1.0 M) was used as feed solution, toluene-Aliquat336 (0.02 M) as membrane solution combination and HCl (0.5 M) as stripping solution. Modeling studies established that the nonsteady state approach better represented zinc transport. It was therefore concluded that the zinc transport mechanism was affected by interface reactions rather than diffusion. © by PSP Daha fazlası Daha az

Altın, Süreyya | Altın, Ahmet

Article | 2019 | Journal of Electrochemical Science and Technology10 ( 1 ) , pp.14 - 21

Supported liquid membrane process usually is used for recovering or enrichment of valuable metals in the industrial wastewater. But, even if the metals in the wastewater was separated with high chemical selectivity, it cannot be enough concentrated since separation performance of supported liquid membrane (SLM) process is limited by concentration gradient between feed solution and stripping solution. If metal concentration in the stripping solution to be enough low, transport of metal through membrane can be accomplishment constantly. Therefore, Electrodialysis (ED) has been placed after SLM process and the stripping solution of SLM . . . was used as the feed solution for the ED process. Transport of ions in the solutions is successfully performed by ED process. Thus, the metal concentration in the stripping solution does not rise as to stop ion transport. Besides, valuable metals easily are concentrated by ED process for re-use. In this study, effects of operation parameters like initial Cd(II) concentration, HCl concentration in the feed solution of SLM and applied voltage are investigated on separation efficiency, flux and permeability of the both processes. As the feed solution concentration increased, all performance values has increased. When initial concentration of 100 mg/L is used, separation performances (SP) are 55% and 70%, for SLM and consecutive process, respectively. The best HCl concentration in the feed solution of SLM has determined as 2 M, in this conditions SP are 64% and 72%, for SLM and consecutive process, respectively. With increased of applied voltage on ED process, SP of the consecutive process has been raised from 72% to 83%. According to the obtained experimental data, consecutive process has better separation performance than SLM. When the separation performances of both processes were compared for the same operating conditions, it was determined higher the separation efficiency, permeability and flux values of the consecutive process, 8%, 9% and %10.6, respectively. Consequently, the use of the consecutive process increases the performance efficiency of both processes. The consecutive process studied has quite a good chemical separation efficiency, and enrichment capability. Moreover, this process requires few water and energy. © 2019, Korean Electrochemical Society. All rights reserved Daha fazlası Daha az

Altın, Süreyya | Alemdar, Sonay | Altın, Ahmet | Yıldırım, Yılmaz

Article | 2011 | Separation Science and Technology46 ( 5 ) , pp.754 - 764

Selective removal of cadmium from wastewaters is very important, because cadmium is toxic for the environment and for human health. This work is a comprehensive study on the selective removal of Cd(II) from aqueous solutions by using a co-current flow flat sheet supported liquid membrane system. 4.4 × 10-4M Cd(II) concentration was used as a feed solution in the experiments. Toluene containing Aliquat 336 was used as the membrane liquid in the membrane system. Parameters such as the properties of feed and stripping solutions, carrier concentration, and flow rate, which have roles in transport of Cd(II) ions, were optimized. The effi . . .ciency of the system is expressed in terms of permeability and flux values, and transport efficiency. The optimum process conditions for the Cd(II) transport are experimentally found as follows: The feed solution as 2 M HCl, the carrier concentration as 0.1 M Aliquat 336, the stripping solution as 0.06 M EDTA, and the flow rates for the feed and stripping solutions as 50 mL/min and 80 mL/min, respectively. Under these conditions, the Cd(II) transport efficiency is found to be 82%. © Taylor & Francis Group, LLC Daha fazlası Daha az

Altın, Süreyya | Demircioğlu, Nuhi | Peker, İbrahim | Altın, Ahmet

Article | 2007 | Colloids and Surfaces A: Physicochemical and Engineering Aspects306 ( 1-3 SPEC. ISS. ) , pp.14 - 21

In this study, the effects of the acceptor phase and the donor phase properties on sodium ion transport were examined in bulk liquid membrane systems. In the experiments, toluene and a mixture of toluene-dichloromethane (90-10%, v/v) containing 1 × 10-3 M DB18C6 (dibenzo18crown6) was used as the membrane. In order to examine the effects of different the acceptor phases, firstly H2SO4, HCl, HNO3, CH3COOH and distilled water were used as the acceptor phases. Furthermore, the experiments were performed by using various acid concentrations such as 2, 0.2 and 0.02 M of acids, as the acceptor phase. In the second part of the study, the ef . . .fect of donor phase on sodium ion transport was examined. For this examination, Na2SO4, NaNO3, NaOH and NaCl were applied. In order to determine the effect of the donor phase concentration, the experimentation was performed using 1.08 × 10-2, 2.17 × 10-2, 3.26 × 10-2 and 4.34 × 10-2 M concentrations of Na+ in form of NaCl. Finally, nonsteady-state kinetics was applied on all data obtained from the experiments and reaction constants (k1, k2, and k3) and the values of the Rmax, tmax, k1/k2 were calculated. Consequently, it was determined that the type and the concentration of the acceptor phase and the donor phase solutions were significant for transport efficiency in liquid membrane systems. The most efficient transport was obtained by applying 2 M H2SO4 and 2.17 × 10-2 M Na+ in form of NaCl. Besides, It was observed that there was a significant effect of the anion attached to the cation on transport efficiency. © 2007 Elsevier B.V. All rights reserved Daha fazlası Daha az

Altın, Süreyya | Yıldırım, Yılmaz | Altın, Ahmet

Article | 2010 | HYDROMETALLURGY103 ( 01.Apr ) , pp.144 - 149

Toxic metals from industrial wastewaters are an important environmental issue. The use of supported liquid membrane processes has gained momentum in recent years, as it allows the reuse of water and toxic metals. The aim of this study is to investigate the active transport of silver ion through a supported liquid membrane (micro-porous Fluoropore PTFE) of DC18C6 (Dicyclohexano18crown6) in toluene under various experimental conditions. For this purpose, the effects of various parameters including binary carriers, carrier concentration, feed phase concentration, the nature and concentration of stripping agents in the stripping phase a . . .nd flow rates of feed and stripping phases on transport efficiency were also investigated. The maximum transport efficiency was observed at the following conditions: flow rates of 50 mL/min in both phases, 0.05 M DC18C6 in toluene as carrier solution. 50 ppm Ag(+) dissolved in 0.015 M HNO(3) as feed solution and 0.08 M Na(2)S(2)O(3) as stripping solution Optimum operation time was determined as 240 min. Under these conditions, 94% of the silver ions were transported from the feed phase to the membrane phase. However, the transport rate from the membrane phase to the stripping phase remained at approximately 81%. (C) 2010 Elsevier B.V. All rights reserved Daha fazlası Daha az

Altın, Süreyya

Article | 2011 | INTERNATIONAL JOURNAL OF CHEMICAL REACTOR ENGINEERING9 , pp.144 - 149

This study aims to investigate color and COD removal efficiencies of electrocoagulation (EC) process for dye solutions simulated by using polyvinyl alcohol (PVA) and reactive dyestuff of Remazol Turquoise Blue (G-133). The two different electrode configurations, namely monopolar and bipolar, were examined to find out the better alternative intensifying the performance of the process. The results obtained from these tests show that an EC cell with bipolar electrodes has produced slightly higher color and COD removal efficiencies than that of an EC cell with monopolar electrodes. The best removal efficiencies have been found for the b . . .oth electrode configurations under the conditions that the time of electrolysis is 30 min, the constant direct current (DC) value 0.75 A and the initial pH value 3. Consequently, the bipolar electrode configuration (BPEC) has yielded 72.7 percent COD and 99.8 percent color removals while the monopolar electrode configuration (MPEC) producing 65.2 percent COD and 99.6 percent color removals Daha fazlası Daha az