Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Impact of Titania Phase Structure and Surface Reactivity on the Photocatalytic Degradation of Various Dyes and Textile Wastewater(National Institute of Science Communication and Policy Research, 2023) Yurtsever, Hüsnü Arda; İloğlu, Onur; Çiftçioğlu, MuhsinTitania (TiO2) powders have been prepared by precipitation method in different precipitation media which contain sulfate, nitrate or organic species. Photocatalytic degradation of different dyes and a real textile wastewater have been conducted with these powders along with commercial powder Degussa P25 for comparison. Ethyl alcohol (organic medium), sulfuric acid (sulfate medium) and nitric acid (nitrate medium) have been used to dissolve titanium precursor for the precipitation of TiO2 in ammonia solution. UV-Vis DRS and XPS results indicate that S doping in sulfate medium precipitated powder and N doping in nitrate medium precipitated powder has been occurred and the presence of S or N containing impurities on the grain boundaries have been improved light absorption of TiO2 significantly. However, these powders have exhibited low surface reactivities. The highest surface reactivity has been obtained with the powder precipitated in organic medium which also has the highest crystallite sizes (76 nm rutile and 34 nm anatase crystallites) with relatively low rutile weight percentage (10.0%). The surface-normalized rate constants of this powder are 0.02038 min-1.m-2 in real textile wastewater degradation and 0.0161 min-1.m-2 in methyl orange degradation, which are 0.01563 and 0.0091 min-1.m-2, respectively, for Degussa P25. Results have shown that this powder show 30-70% higher surface reactivities compared to Degussa P25. The main structural difference of organic medium precipitated powder and Degussa P25 has been found to be the anatase-rutile weight ratio and crystallite size of rutile phase whereas band gap energy of Degussa P25 is lower and other properties are not significantly different.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: 2Citation - Scopus: 2Comparison of Photocatalytic Properties of Tio2 Thin Films and Fibers(EDP Sciences, 2016) Özdemir, Mehtap; Kurt, Metin; Özyüzer, Lütfi; Aygün, GülnurEfficiency of solar panels degrades as a result of organic contamination such as airborne particles, bird droppings and leaves. Any foreign object on photovoltaic panels reduces the sunlight entering the absorbing surface of the solar panels. Since this leads to a major problem decreasing in energy production, solar panels should be cleaned. The self-cleaning method can be preferred. There are some methods to clean the surface of solar panels. Among the self-cleaning materials, TiO2 is the most preferable ones because of its powerful photocatalytic properties. In this study, photocatalytic TiO2 were produced in two different nanostructures: nanofibers and thin films. TiO2 nanofibers were successfully produced by electrospinning. TiO2 thin films were fabricated by reactive magnetron sputtering technique. Both TiO2 nanofiber and thin film structures were heat-treated to form TiO2 in anatase phase at 600 °C for 2 h in air. Then, they were evaluated by SEM analyses for morphology, X-ray diffraction (XRD) analyses for phase structures, X-ray photoelectron spectroscopy (XPS) for the chemical state and atomic concentration, and UV-spectrometer for photocatalytic performance. The results indicate that photocatalytic and transmittance properties of TiO2 thin films are better than those of nanofibers. Consequently, TiO2 based thin films exhibit better performance for solar cell applications due to the surface cleanliness.