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Hematite (Fe 2 O 3 ) thin films have been synthesized on indium tin oxide (ITO)coated glass substrate using an electrodeposition technique and the changes in their structure due to subsequent annealing at different temperatures investigated. The structural, optical, and morphological properties of Fe 2 O 3 thin films formed after annealing at temperatures of 500°C, 550°C, and 600°C after deposition were determined by x-ray diffraction (XRD) analysis, absorption spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM). XRD analysis of the annealed electrodeposited samples revealed Fe 2 O 3 thin films with rhombohedral crystal structure. The energy bandgap of the Fe 2 O 3 films grown on ITO and annealed at different temperatures was calculated based on absorption measurements, yielding values between 2.0 eV and 2.2 eV. Raman peaks were observed between 210 cm À1 and 1305 cm À1 depending on the annealing temperature. SEM analysis clearly revealed the crystal structure belonging to Fe 2 O 3 and an increase in the particle size as the annealing temperature was increased. The surface roughness values (in the range from 11 nm to 46 nm) obtained from AFM images of the samples annealed at different temperatures were compatible with the average roughness values (in the range from 14 nm to 51 nm). The results of these analyses confirm that the structure of the a-Fe 2 O 3 thin films was improved by increasing the annealing temperature. Electrochemical impedance spectroscopy (EIS) and Tafel measurements enabled detailed examination of the corrosion behavior of the a-Fe 2 O 3 films deposited on the ITO substrate. Nyquist and Bode analyses were applied to determine the structural changes to the Fe 2 O 3 and its corrosion behavior. The R s values calculated with the help of Nyquist plots increased from 65.10 X cm 2 to 540.5 X cm 2 with increase of the annealing temperature, while the R ct values decreased from 64.29 9 10 9 X cm 2 to 1.142 X cm 2 after annealing. The corrosion current and potential parameters were also calculated from Tafel measurements after deposition and annealing at different temperatures.

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In this study, Cr(III) removal from aqueous solutions was investigated by using the batch adsorption method. Orange peel activated with potassium carbonate (OPAPC) was used as the adsorbent because of the fact that adsorption capacity was higher when orange peel was activated with potassium carbonate, instead of both original orange peel and orange peel activated with phosphoric acid adsorbents. In order to determine optimum adsorption conditions, adsorbent concentration (2-15 g/L), pH (3-7), temperature (298-318 K), contact time (10-240 min) and initial concentration of Cr(III) (5-50 mg/L) were investigated for Cr(III) removal from aqueous solutions using OPAPC. The equilibrium data were evaluated using the Langmuir and Freundlich model equations and the kinetic data were evaluated with pseudo first and second order kinetic models. In addition, the adsorption thermodynamics of the proposed method in optimum conditions was investigated.