Environmental Engineering / Çevre Mühendisliği
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Article Citation - WoS: 7Citation - Scopus: 11A Box–behnken Design (bbd) Optimization of the Photocatalytic Degradation of 2,4-Dichlorophenoxyacetic Acid (2,4-D) Using Tio2/H2o2(Desalination Publications, 2018-08) Doğdu Okçu, Gamze; Baldan Pakdil, Nazlı; Ökten, Hatice Eser; Yalçuk, Arda; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology2,4-Dichlorophenoxyacetic acid (2,4-D), a chlorinated phenoxy-alkanoic herbicide, is used extensively in agriculture. This work investigates TiO2/H2O2 mediated UV photocatalytic degradation of 2,4-D in a laboratory-scale photoreactor. Three levels of Box–Behnken design technique, combined with response surface methodology (RSM), were used to design the experiments. Two kinds of multivariate experimental design (pH, TiO2, and 2,4-D concentration) and (pH, TiO2, and H2O2 concentrations) were employed to establish two quadratic models (Model 1 and Model 2), showing the functional relationship between degradation rate of 2,4-D and three independent experimental parameters. Model 1 predicted optimum values for pH, TiO2, and 2,4-D concentrations to be 5.7, 1.20 g L−1, and 32 mg L−1, respectively. Model 2 predicted optimum values for pH, TiO2, and initial H2O2 concentrations to be 4.94, 1.34 g L−1, and 161 mg L−1. Degradation rate of 2,4-D approached 78.10% for Model 1 and 83.63% for Model 2. For both models, similar results were obtained through optimizing variables by RSM and using single factorial batch reactor operation. Regression analysis showed good agreement between experimental results and predictive values for Models 1 and 2, with R2 values of 0.9958 and 0.9976, respectively.Article Citation - WoS: 4Citation - Scopus: 5Combined Influence of Some Cations on Arsenic Removal by an Air-Injection Ec Reactor Using Aluminum Ball Electrodes(Desalination Publications, 2020) Gören, Ayşegül Yağmur; Kobya, Mehmet; Şık, Emrah; Demirbaş, Erhan; Öncel, Mehmet Salim; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyCombined effects of some cations such as calcium (Ca2+), iron (Fe2+), manganese (Mn2+), and magnesium (Mg2+) and operating time on the removal of arsenic by air-injected electrocoagulation (EC) reactor with aluminum (Al) ball electrodes were investigated. The operating conditions were optimized with the Box-Behnken design of response surface methodology (RSM). The response variables were selected from the program as removal efficiency, residual arsenic concentration, energy consumption and operating cost (OC) in the EC process. A total of 46 experimental run was performed. The removal efficiency of arsenic increased with an increase in iron concentration (0.5-4.5 mg/L). The rest of the cations showed no noticeable effect on arsenic removal efficiency. The maximum arsenic removal efficiency and minimum OC at the optimum operating conditions (C-Ca: 305 mg/L, C-Mg: 42 mg/L, C-Fe: 3.3 mg/L, C-Mn: 2.34 mg/L, initial pH of 7.5 applied current of 0.15 A, Al ball size of 7.5 mm, 5.0 cm of Al ball anodes height in the EC reactor, air-fed rate of 6.0 L/min and t(EC): 16.83 min) in the EC process were 99.9% and 0.0332 $/m(3) for initial arsenic concentration of 200 mu g/L, respectively. The removal mechanism of As(III) by EC seems to be oxidation of As(III) to As(V) and subsequent removal by adsorption/complexation with aluminum hydroxides generated in the process. The results showed that the air-injected EC reactor can be used effectively for arsenic and hardness removal simultaneously from real groundwater sources.Article Citation - WoS: 21Citation - Scopus: 21Comparison of Ozonation and Coagulation Decolorization Methods in Real Textile Wastewater(Desalination Publications, 2018-01) Aydın, Muhammed Iberia; Yüzer, Burak; Öngen, Atakan; Ökten, Hatice Eser; Selçuk, Hüseyin; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologySeveral treatment approaches such as ozonation, metal coagulation, (ferric chloride and alum), polymer treatment (Polyethylene polyamine, PP, and Cyanoguanidine Polymer, CP) and their combinations for decolarization of biologically treated textile wastewater (BTTWW) were applied. Wastewater samples were taken from effluent stream of an activated sludge treatment system in a synthetic-cotton textile factory. Absorbance, color, chemical oxygen demand (COD) measurements were done to determine optimum conditions. At coagulation experiments, neither ferric chloridenoralum decreased the color parameter below the discharge standard. Ozonation was found to be efficient in removing color from BTTWW as color degradation reached steady-state after 10 min. However color standard was met at higher ozone dosages (20 min). Polymer coagulation (200 mg/L) was found to be practical in removing color from BTTWW. Ozonation prior to polymer coagulation (pre-ozonation) not only improved the color removal efficiency but also decreased the required polymer dosage by 75%. Operational costs of ozonation, PP and pre-ozonation-subsequently PP were found to be 0.37 €/m3, 0.50 €/m3, and 0.26 €/m3, respectively.Article Citation - WoS: 4Citation - Scopus: 7Heterogeneous Photocatalytic Degradation and Mineralization of 2,4-Dichlorophenoxy Acetic Acid (2,4-D): Its Performance, Kinetics, and Economic Analysis(Desalination Publications, 2019-01) Doğdu Okçu, Gamze; Ökten, Hatice Eser; Yalçuk, Arda; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThe photocatalytic degradation and mineralization of commercial solution of 2,4-dichlorophenoxy-acetic acid (2,4-D) was carried out by UVA/P25 TiO 2 and UVA/P25 TiO 2 /H 2 O 2 oxidation processes under batch-mode conditions. In UVA + TiO 2 photocatalysis (TiO 2 1.5 gL −1 , pH 5, initial 2,4-D 25 mg L −1 ), 97.47% ± 0.27% degradation, 39.89% ± 3.42% mineralization, and 65.52% ± 4.88% oxidation were achieved in 180 min, and in UVA +TiO 2 + H 2 O 2 photocatalysis (TiO 2 1.5 g L −1 , pH 5, initial 2,4-D 25 mg L −1 , H 2 O 2 150 mg L −1 ), 99.74% ± 0.08% degradation, 55.99% ± 2.67% mineralization, and 82.49% ± 1.90% oxidation were obtained in 180 min. The pseudo-first-order kinetic model fitted the experimental data well, and the photocatalytic degradation process was explained by the modified L–H model; k c and K LH were 1.293 mg L −1 min −1 and 0.232 L mg −1 , respectively. Fourier transform infrared (FTIR) spectroscopy spectra and scanning electron microscopy (SEM) analysis indicated degradation of organic bonds of the herbicide and adsorption of 2,4-D particles onto the TiO 2 catalyst during 24-h experiments. Moreover, the dependence of k app on the half-life time was determined by calculating the electrical energy per order (E EO ). UVA/TiO 2 /H 2 O 2 photocatalysis may be applied as a pretreatment to 2,4-D herbicide wastewater at a pH of 5 for biological treatment.Article Citation - WoS: 3Citation - Scopus: 5Optimization of Some Cations for Removal of Arsenic From Groundwater by Electrocoagulation Process(Gheorghe Asachi Technical University of Iasi, 2018) Kobya, Mehmet; Şık, Emrah; Demirbaş, Erhan; Gören, Ayşegül Yağmur; Öncel, Mehmet Salim; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis study dealt with investigation of arsenic removal from groundwater using electrocoagulation (EC) method in a batch mode by the Box-Behnken experimental design method. Effects of some cations like Ca, Fe, Mg, Mn and operating time on the removal were explored by an air injected EC reactor. The combined effects of these variables were analyzed by the quadratic model for predicting the highest removal efficiency of arsenic from groundwater. The arsenic removal efficiency was found to be dependent on increase with operating time and concentrations of Ca, Mg, Fe and lower concentration of Mn. When operating variables were considered as minimum operating cost and maximum removal efficiency, the optimum operating parameters were determined to be 132 mg/L of CCa, 55 mg/L of CMg, 4.5 mg /L of CFe, 4.5 mg/L of CMn and operating time of 3 min to meet the target concentration of <10 μg/L. Values of removal efficiency and operating cost at the optimum conditions were 95.1% and 0.041 $/m3.Article Citation - WoS: 3Citation - Scopus: 3Selection of Alternative Landfill Location by Using a Geographical Information System. European Side of Istanbul. Case Study(Technical University of Wroclaw, 2016) Demir, Göksel; Kolay, Umut E.; Ökten, Hatice Eser; Alyüz, Ümmügülsüm; Bayat, Cuma; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyOne of the most difficult tasks encountered when implementing waste management practices in Turkey involves the selection of the most suitable area for a landfill. The Geographic Information System (GIS) which possesses the ability to imitate and process economic and environmental constraints, presents itself as a useful and effective decision support tool. This study will utilize the GIS to determine feasible alternative landfill areas on the European side of Istanbul, which has a high density population, showing that accurate selection results can be achieved at lower cost.Editorial Special Issue on the 4th International Conference on Recycling and Reuse 24–26 October 2018, Istanbul, Turkey: Preface(Elsevier B.V., 2019) Okten, H.E.; Balkaya, N.; Aydin, S.; Elmaslar, E.; Ongen, A.; Selcuk, H.; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyArticle Citation - WoS: 1Citation - Scopus: 2Use of Nano Zero-Valent Iron Coated Coffee Grounds for Removal of Zn(ii) and Ni(ii) From Aqueous Solutions(Desalination Publications, 2019-12) Gören, Ayşegül Yağmur; Genişoğlu, Mesut; Ökten, Hatice Eser; 03.07. Department of Environmental Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis research investigates the adsorption capacity of a novel composite material, namely nano zero-valent iron coated coffee grounds (nZVI-CG), for removal of zinc (Zn) and nickel (Ni). nZVI particles were synthesized and immobilized to the surface of waste coffee grounds (CG) using the ultrasonic-assisted liquid phase method. Characterization of synthesized nZVI-CG composite and bare CG showed that nZVI coating has increased the surface area significantly. Batch tests were conducted to examine the effects of pH, reaction time and initial metal concentrations on Zn2+ and Ni2+ removal. At an initial metal concentration of 10 mg-Ni/L and 10 mg-Zn/L, nZVI-CG removal rates for Zn2+ and Ni2+ were observed as 98.89% and 97.29%, respectively; while removal rates of bare CG have remained at 51% (Zn2+) and 48.1% (Ni2+). Moreover, acidic conditions were observed to deteriorate Ni2+ and Zn2+ adsorption since most functional groups of the metals were protonated. Increasing initial nickel and zinc concentrations decreased removal rates. While the model fittings improved with increasing pH, in the case of nZVI-CG, Langmuir isotherm gave the best fits for Ni2+ and Zn2+ at pH 5 and 7. Also, our experimental results followed the pseudo-second-order kinetic model, regardless of the used adsorbent. Consequently, our results showed that nZVI-CG composite material is a promising alternative adsorbent for pilot scale metal removal/recovery applications.
