Environmental Engineering / Çevre Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4321
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Article Citation - WoS: 8Citation - Scopus: 12A Box–behnken Design (bbd) Optimization of the Photocatalytic Degradation of 2,4-Dichlorophenoxyacetic Acid (2,4-D) Using Tio2/H2o2(Desalination Publications, 2018) Doğdu Okçu, Gamze; Baldan Pakdil, Nazlı; Ökten, Hatice Eser; Yalçuk, Arda2,4-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: 5Citation - Scopus: 5A Hybrid Process for 2,4-Dichlorophenoxy Acetic Acid Herbicidal Treatment and Its Microbial Identification by Maldi-Tof Mass Spectrometry(Taylor and Francis Ltd., 2020) Doğdu Okçu, Gamze; Ökten, Hatice Eser; Yalçuk, ArdaThe feasibility of coupling photocatalysis and a biological treatment to remove a herbicide–2,4-dichlorophenoxy acetic acid (2,4-D)–from pure water was examined using batch experiments following three protocols: aerated (A-BR) and non-aerated biodegradation (NA-BR) alone, and intimately combined photodegradation and biodegradation (P-B). In view of a subsequent biological treatment, 15 and 180 min irradiation times were chosen in accordance with spectrophotometric and LC-MS/MS results that indicated the decrease in the COD/TOC ratio during photocatalysis. Pre-treatment led to a quick decrease in concentration of 2,4-D and COD during the biological process: a 78.79 ± 0.30% COD removal and 38.23 ± 3.12% 2,4-D elimination was measured after 5760 min in A-BR, and 80.89 ± 0.81% COD and 81.36 ± 1.37% 2,4-D removal was achieved after 2880 min in P-B. For species identification using matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-TOF/MS equipment, Aeromonas eucrenophila, Stenotrophomonas acidaminiphila, Ralstonia pickettii, Sphingobacterium multivorum and Acinetobacter towneri were identified with high accuracy, and they play important roles in the degradation of 2,4-D.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) Doğdu Okçu, Gamze; Ökten, Hatice Eser; Yalçuk, ArdaThe 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.