Page - 145 - in Advanced Chemical Kinetics

Na2CO3 solutionunder vigorous stirring for 2 h at room temperature. The resulting product was collected by centrifugation, washedwith deionizedwater several times, dried at 100�C overnightandcalcinedat500�C.Finally, thesamplesweredesignatedas0.125MZnO,0.25M ZnOand0.5MZnO. Raw Sep and FA used as supports in this study were obtained from Eskişehir-region of Anatolia and Soma (Turkey), respectively. Theywere characterized byX-ray diffraction and SEM-EDX analyses [18, 19]. Supported catalystswere preparedwith the addition of FA-Sep dispersions (1:1 w/w, stirred about 12 h) into the above-mentioned ZnO solutions. The resulting product was collected by centrifugation, washedwith deionizedwater for several times,driedat100�Covernightandcalcinedat500�C.Finally, thecatalystsweredesignatedas 0.125MZnO-FA-Sep,0.25MZnO-FA-Sepand0.5MZnO-FA-Sep. X-ray diffraction patternswere recorded on an X-ray diffractometer (Rigaku-D/MAX-Ultima- diffractometer, 40kV,and40mA)equippedwithgraphitemonochromatizedCu-Kα1 radiation (λ = 1.54Å) at a scan rate of 2�min�1. Brunauer-Emmett-Teller (BET)-specific surface area and pores size were determined from the nitrogen adsorption apparatus (Quantachrome Nova 2200e) at 77K. Prior to themeasurements, the sampleswere pretreated in a vacuumat 473K for 24 h. Themorphology of the productswas investigated by scanning electronmicroscopy (ESEM-FEG/EDAXPhilips XL-30) running at an accelerating voltage of 20 kV. The elemental compositionof thecompositeswasdeterminedbyenergydispersiveX-rayspectroscopy (EDS). X-rayphotoelectron spectroscopy (XPS) datawere recordedwith aThermoScientificK-Alpha Photoelectron Spectrometer usingAlKα (12.5 kV)X-ray source. Calibration of the instrument wasdoneviacarbonpeak[21,22].UV-visible (UV-vis) absorptionspectrawererecordedwitha ShimadzuUV-2450. Diffuse reflectancemeasurements (DRS)were recorded by using an inte- gratedspherereflectanceaccessorywithBaSO4reference. Thephotodegradationofmethylorange (MO)-probemolecule in this studywascarriedoutat room temperature in a homemade photocatalytic reactor under UV light (Philips TL 15W/ 5BLB,λ=365nm,anincidentphotonfluxof4.7�1015photonss�1) [12,18].Atypical reaction systemincluded0.2gofacatalystand200mLofaknownconcentrationofMO.Thesuspension was stirred in the dark for 30min. Thereafter, irradiationwas started andUV-vis absorption spectrawererecordedtomonitorbothdegradationanddecolorizationprocesses.Thedecrease of thebandat274nmindicateddegradationofMO’saromaticmoietywhile theoneat464nm was followed for thedecolorizationofMOsolution.All experimentswereperformedat room temperature and at pH= 8 (3.27mgL�1MO in the presence of 0.5MZnO-FA-Sep)without concerning thedegradation intermediates.Also,measurementswere conducted at least twice and the average valuewas recorded. Thedegradation anddecolorization rate percentages of MOwerecalculatedbythefollowingequation: Degradation or decolorizationð Þ%¼C0�C C0 �100 (1) where C0was the initial concentration ofMOandCwas the concentration ofMOafter “t” minutes irradiation. Adsorption, Kinetics and Photoactivity of ZnO-Supported Fly Ash-Sepiolite Ternary Catalyst http://dx.doi.org/10.5772/intechopen.70504 145