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Öğe Decolorization of Reactive Black 5 Using N-Doped TiO2(Gazi Univ, 2022) Berkta, Asli; Kartal, Ozlem EsenDecolorization of Reactive Black 5 (RB5) was investigated by heterogeneous photocatalysis using N-doped TiO2. N-doped TiO2 photocatalysts were synthesized by means of a sol-gel process. The characterization of synthesized samples was performed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy measurements. Photocatalytic activity of N-doped TiO2 samples was assessed by following decolorization and degradation efficiency of RB5. N-TiO2(3) sample yielded the highest decolorization efficiency. The apparent first-order rate constants for decolorization of RB5 with N-TiO2(X) samples followed the order of N-TiO2(3) > N-TiO2(2) > N-TiO2(4) > N-TiO2(1). Improvement of decolorization efficiency of TiO2 was observed doping with nitrogen. The effect of actual sunlight on decolorization efficiency was also investigated. 96% and 49% of decolorization efficiency levels were attained within 60 minutes of reaction time with outdoor sunlight and fluorescent daylight lamps, respectively.Öğe Decolorization of Reactive Red 239 Using UV-C Activated Peroxydisulfate(Hard, 2019) Kartal, Ozlem EsenDecolorization of Reactive Red 239 (RR239) using a sulfate radical (SO4 center dot-)-based advanced oxidation process was investigated in a batch photoreactor. SO4 center dot- was generated in situ through activation of peroxydisulfate under UV-C illumination. Effect of initial pH (3-9), initial dye concentration (20-50 mg dm(-3)), S2O82- dosage (0-3 mmol dm-3) and lamp power (0-16 W) were explored. It was found that initial pH of RR239 solution had no considerable effect on decolorization efficiency. Experimental results demonstrated that decolorization efficiency enhanced with increasing S2O82- dosage and lamp power and decreasing initial dye concentration. Quenching experiments were performed with alcohols to determine the dominant radical. Under the conditions tested in this study, 98% and 70% decolorization and aromatic degradation efficiencies were obtained within 120 min of irradiation time, respectively. Decolorization and aromatic degradation efficiencies of RR239 in PS/UV-C and PMS/UV-C systems were evaluated in terms of electrical energy consumption per order by figure of merit approach.Öğe Decolourization of CI Reactive Orange 16 via photocatalysis involving TiO2/UV and TiO2/UV/oxidant systems(Desalination Publ, 2012) Kartal, Ozlem Esen; Turhan, Gulistan DenizDecolourization of C.I. Reactive Orange 16 (RO16) via photocatalysis involving TiO2/UV and TiO2/UV/oxidant systems has been investigated. The experiments were carried out in a stirred cylindrical batch photoreactor under UV irradiation. The effects of pH, TiO2 concentration and addition of electron acceptors such as H2O2, Na2S2O8 and Cu+ ions were studied. The decolourization efficiency followed the order of pH 3 > pH 9 > pH 6 in TiO2/UV system. The addition of Cu+ ions to TiO2/UV/oxidant system significantly increased the decolourization efficiency. The performance of addition of 0.5 mM Cu+ ions to TiO2/UV/Na2S2O8 system was also evaluated by using synthetic dye-bath effluent. The results reveal that almost complete decolourization (99%) was achieved with RO16, while 76% decolourization was obtained with synthetic dye-bath effluent after 360 min of reaction time. Similar trend was observed with COD measurements. The rate of decolourization of RO16 was found to follow pseudo-first order kinetics and obeys L-H model. When the suspension of TiO2 containing RO16 was exposed to solar irradiation, 90% of decolourization and 64% of COD removal were obtained after 120 min of reaction time. Degradation products of RO16 were determined by LCMS.Öğe DETERMINATION OF ELECTRICAL ENERGY COST OF DECOLORIZATION OF CI ACID ORANGE 7 VIA TIO2-ASSISTED PHOTOCATALYSIS UNDER UV ILLUMINATION IN THE PRESENCE OF H2O2(Gh Asachi Technical Univ Iasi, 2017) Kartal, Ozlem Esen; Turhan, Gulistan DenizDecolorization of C.I. Acid Orange 7 (AO7) via TiO2-assisted photocatalysis under UV illumination in the presence of H2O2 has been investigated. The effect of pH on decolorization efficiency of AO7 was investigated in TiO2/UV/H2O2 process. The performance of TiO2/UV/H2O2 system was also evaluated by using synthetic dye-bath effluent of AO7. Solar driven TiO2 photocatalysis was found significantly efficient for the decolorization and degradation of AO7. The rates of decolorization and degradation of AO7 were found to follow pseudo-first order kinetics. The electrical energy consumption of decolorization of synthetic dye-bath effluent was found to be 4.1 times higher than that of AO7 solution. Similarly, the electrical energy consumption of degradation of synthetic dye-bath effluent was 2.2 times higher than that of AO7 solution under investigated conditions. Considering one order of magnitude reduction in AO7 concentration and COD value, the cost of electrical energy for decolorization and degradation of AO7 solution and synthetic dye-bath effluent of AO7 was calculated.Öğe Investigation of photocatalytic activity of TiO2 nanotubes synthesized by hydrothermal method(Taylor & Francis Inc, 2023) Karakurt, Huseyin; Kartal, Ozlem EsenTiO2 nanotubes were synthesized by hydrothermal reaction using commercially available TiO2 powder at 150 degrees C for 24 h. The transmission electron microscopy, X-ray diffraction, nitrogen adsorption-desorption isotherms and Fourier Transform-Infrared spectroscopy were used to characterize the nanotubes. Anatase phase was not transformed into rutile phase in the range of calcination temperature studied. Increase in calcination temperature result in enhancement of crystallinity and reduction in BET surface area. Photocatalytic removal of Reactive Red 239 (RR239) was investigated using prepared TiO2 nanotubes. Effects of pH, TiO2 nanotube dosage, initial RR239 concentration and calcination temperature were studied. 99%, 97% and 55% of removal efficiency values were attained at pH = 3, 5 and 7, respectively within 60 min or reaction time. With an increase in dosage of TiO2 nanotube in the range of 0.25-0.75 g dm(-3), removal rate increased by a steeper slope. Complete removal of RR239 was observed at 20 mg dm(-3) RR239 concentrations within 30 min but longer time was required for complete removal at higher concentrations. Langmuir-Hinshelwood kinetic expression was proposed based on nonlinear regression analysis. The removal efficiency of nanotubes calcined at 300 - 450 degrees C significantly increased but further increase in calcination temperature caused to decrease the efficiency.100% and 85% removal efficiency values were observed using actual solar light within 120 min of reaction time in July and January, respectively. Experiments conducted with scavengers showed that holes and adsorbed hydroxyl radicals were the major species involved in removal of RR239. A pathway for degradation of RR239 was suggested according to detected intermediate compounds.Öğe LIQUEFACTION OF NIGDE-ULUKISLA OIL SHALE: THE EFFECTS OF PROCESS PARAMETERS ON THE CONVERSION OF LIQUEFACTION PRODUCTS(Estonian Academy Publishers, 2017) Kartal, Ozlem Esen; Akin, Serhat; Hascakir, Berna; Karaca, HuseyinIn this paper, the direct liquefaction of Turkish Nigde-Ulukisla oil shale in noncatalytic and catalytic conditions was studied. The effects of pressure, tetralin/oil shale ratio, catalyst type and concentration, reaction time and temperature and oil shale/waste paper ratio on the process were investigated. It was found that tetralin/oil shale ratio had no considerable effect on the total and liquefaction products conversions under the noncatalytic conditions. Fe2O3, MoO3, Mo(CO)(6), Cr(CO)(6) and zeolite were used as catalysts in catalytic liquefaction. The highest total and liquefaction products conversions were obtained using MoO3 as catalyst at a concentration of 9% by weight. Reaction temperature of 400 degrees C and reaction time of 90 minutes were chosen according to obtained liquefaction results. Co-liquefaction experiments were performed using waste paper. Both the total and oil + gas conversions were increased to a considerable extent by the application of the co-liquefaction process. According to gas chromatographic-mass spectrometric (GC-MS) analysis, the liquid product from the liquefaction process of oil shale under catalytic conditions of experiment 22 consisted mainly of naphthalene and its derivatives and polycyclic hydrocarbon such as indene and its derivatives.Öğe Modeling and optimization of decolorization of CI Reactive Orange 16 via SO4•- radicals by response surface methodology(Desalination Publ, 2018) Kartal, Ozlem EsenModeling and optimization of decolorization of C.I. Reactive Orange 16 (RO16) via SO4 center dot- by response surface methodology (RSM) have been investigated. SO4 center dot- was generated in situ by activation of persulfate via UV irradiation. Planning of experimental runs was made by central composite design technique of RSM. A 2(4) full factorial design was applied to evaluate the interactive effects of process variables of Na2S2O8 dosage (X-1, g L-1), initial dye concentration (X-2, mg L-1), temperature (X-3, degrees C) and time (X-4, min) on decolorization efficiency considered as response (Upsilon). A second-order model for decolorization of RO16 was obtained and the experimental results fitted the model predictions well. The optimum reaction conditions to obtain maximum decolorization efficiency was found as Na2S2O8 dosage of 1.60 g L-1, dye concentration of 31 ppm, temperature of 33 degrees C and time of 66 min. Quenching studies showed that the main reactive radical was SO4 center dot-. The second-order reaction rate constant between SO4 center dot- and RO16 was found to be 1.36 x 10(9) M-1 s(-1).Öğe PHOTO-FENTON TREATMENT OF CI REACTIVE BLACK 5 BY USE OF RESPONSE SURFACE METHODOLOGY(Parlar Scientific Publications (P S P), 2010) Turhan, Gulistan Deniz; Kartal, Ozlem EsenDegradation of a diazo dye of C I Reactive Black 5 by photo- Fenton process has been investigated Response surface methodology was applied to evaluate the interactive effects of process variables considered as initial concentration of dye, H2O2 and Fe2+ on the process efficiency in terms of % COD removal, and to optimize the process Experimental design using central composite design allowed the development of a second-order model for RB5 degradation The experimental results satisfactorily fitted the model predictions The optimum reaction conditions to obtain maximum % COD removal were found to be 13 236 mM H2O2 0 5 mM Fe2+ and 0 1008 mM RB5 The results suggest that photo- Fenton process is a promising solution for the degradation of RB5 under both UV and sunlightÖğe Photocatalytic activity of La3+-doped TiO2 synthesized via sol-gel method(Ice Publishing, 2013) Turhan, Gulistan Deniz; Kartal, Ozlem EsenLa3+-doped TiO2 samples were synthesized via sol-gel method using titanium tetraisopropoxide as inorganic precursor. The X-ray diffraction, scanning electron microscopy, X-ray phototoelectron spectroscopy (XPS) and nitrogen adsorption measurements were used to characterize the samples. Doping with La3+ inhibited the transformation of anatase phase to rutile during calcination treatment and the growth of crystallite size. XPS analysis confirmed the presence of La3+ in the form of La2O3 on the surface of TiO2. The photocatalytic activity of La3+-doped TiO2 samples was investigated in terms of decolorization and degradation efficiencies of Acid Orange 7 (AO7) dye. It was found that doping with La3+ enhanced the photocatalytic activity of TiO2. The performance of doped samples was also evaluated using synthetic dye-bath effluent of AO7. Solar-driven La3+-doped TiO2 photocatalysis was found significantly efficient for the decolorization and degradation of AO7.Öğe Removal of Reactive Black 5 by UV-C assisted peroxydisulfate process: Effect of parameters, kinetic study, and phytotoxicity assessment(Taylor & Francis Ltd, 2024) Omac, Feyza; Karakurt, Huseyin; Kartal, Ozlem EsenPhotochemical removal of Reactive Black 5 (RB5) was investigated by the UV-C assisted peroxydisulfate (UV-C/PDS) process. Parameters affecting the removal of RB5 were examined. Activation of PDS by UV-C light significantly improved the removal efficiency compared to direct photolysis or PDS alone. The removal of RB5 by UV-C/PDS process fitted well with the pseudo first-order kinetic model under all tested conditions. Almost complete removal of RB5 was achieved at the end of 120 min within the pH range of 3-7, whereas 90.7 and 89.4% removal efficiency values were observed at pH = 9 and 11, respectively. An increase in PDS dosage in the range of 0.25-1 mM led to a rise in removal from 48.5 to 97.3% after 120 min, and a complete removal was observed with a dosage higher than 2 mM. Pseudo firstorder rate constant (kobs) increased linearly with PDS dosage from 0.0058 to 0.0518 min-1 in the 0.25 mM - 2.3 mM concentration range. The removal efficiency decreased with an increase in the initial concentration of RB5 from 20 to 50 mg L-1 and an exponential correlation was observed between kobs and initial concentration of RB5. Scavenging experiments conducted using t-butyl alcohol and ethyl alcohol implied that both sulphate and hydroxyl radicals were involved in the removal of RB5. Adding HCO3- decreased the removal of RB5 within the range of 1-30 mM. The presence of CI- showed a negative impact on the removal at low concentrations (1-15 mM) and NO3- slightly inhibited the removal of RB5. With corresponding stoichiometric PDS dosage, almost a complete mineralisation was achieved for RB5 solution and simulated dyebath effluent after 720 min of reaction time. EE/O values were determined to be 91.0, 76.8, and 41.1 kWh m-3 order-1 for UV-C/H2O2, UV-C/PMS, and UV-C/PDS processes, respectively. The phytotoxicity tests indicated that the intermediates could be more toxic than the parent compound.Öğe Removal of Reactive Red 120 using immobilized TiO2 in the presence of UV light(Springer, 2022) Karakurt, Huseyin; Kartal, Ozlem EsenRemoval of Reactive Red 120 (RR120) dye in aqueous solution was investigated using immobilized TiO2 in the presence of UV light. TiO2 was deposited onto microscope slides by heat attachment method. SEM analyses confirmed that all microscope slides were coated with TiO2 particles completely after single, two, three and four layers coating. The removal efficiency increased with repetitive coating up to three layers. The highest removal efficiency of 94% was obtained at pH 3 within 300 min of reaction time. Complete removal was observed with 5 and 10 mg dm(-3) dye concentrations whereas removal efficiency decreased from 96 to 52% when initial RR120 concentration increased 15 mg dm(-3) to 30 mg dm(-3). The results of nonlinear optimization showed that the kinetics of removal of RR120 in the range of concentration studied described by L-H kinetic expression. The experiments conducted with radical scavengers indicated that hydroxyl radicals and photogenerated hole and electrons were main reactive species in photocatalytic removal of RR120. The photonic efficiency of immobilized system was lower than that of suspended system. Minor drop (6%) in the removal of RR120 with three layers coated slide after four consecutive cycles of 300 min indicated the reusability and stability of coated slides. A possible degradation mechanism for degradation of RR120 was proposed according to detected intermediate compounds. Mineralization of RR120 was monitored by generation of NO3- and SO42- ions in solution during photocatalytic reaction.Öğe Synthesis of ZSM-5 from modified clinoptilolite and its catalytic activity in alkylation of benzene to ethylbenzene(Taylor & Francis Inc, 2008) Kartal, Ozlem Esen; Onal, IsikZSM-5 catalysts were prepared by utilizing clinoptilolite found in Western Anatolia in abundant amounts as a type of natural zeolite. Hydrothermal reaction was conducted with HCl-treated clinoptilolite at 180 degrees C. After characterizing the solid products obtained by this reaction as ZSM-5 by means of XRD, IR, TGA, surface area analyzer, and chemical analysis they were tested as catalysts in benzene alkylation reaction with ethylene leading to ethylbenzene. Catalytic performance of samples prepared in this study was investigated for benzene conversion, ethylbenzene yield, and selectivity. It was found that ZSM-5(A) sample showed performance similar to that of the reference sample (ZSM-5(C)) synthesized by using patented literature information in terms of benzene conversion. When the reaction temperature was increased from 400 to 425 degrees C ethylbenzene yield and selectivity results of ZSM-5(A) sample were improved but coke formation increased. Catalyst test results indicated the possibility of using clinoptilolite as a raw material in the synthesis of ZSM-5 catalyst for alkylation of benzene with ethylene reaction.
