ABSTRACT
Iron oxide (α-Fe2O3) was synthesized from red mud extract followed by hydrothermal reaction at 150 °C/6-24 h in the presence of NH4OH. The crystallinity of α-Fe2O3 increased with reaction time as confirmed by X-ray Diffraction, while Fourier transform infrared spectroscopy and Raman illustrate the symmetric stretching vibration of the Fe-O bond in α-Fe2O3. The X-ray photoelectron spectroscopic analysis shows O 1s spectra at 530.6, 531.2, and 532 eV, signifying the lattice oxygen in Fe-O, surface oxygen defects, and oxygen in adsorbed hydroxyl groups, respectively. The morphology of α-Fe2O3 nanoflakes was noticed from field emission scanning electron microscopy and transmission electron microscopy. The developed particles reveal the BET surface area in the range of 136-347 m2/g. The maximum As(V) adsorption capacity of 32-41 mg/g was obtained for adsorbent dose of 0.25 g/L. The arsenic level could be lowered down to 2-3 µg/L (<10 µg/L as per WHO's limit) with contaminated real water (64 µg/L) using 0.25 g/L of sample dose within 5 min of adsorption.
ABSTRACT
In the present study, Fe-doped barium borosilicate glass has been melted at 1250°C under microwave heating. The iron redox ratio (Fe(2+)/total Fe) in the glass is investigated by two spectrophotometric methods. A novel decomposition technique has been optimized to measure the ferrous oxidation state in glass. Ferrozine was chosen as a specific complexing reagent; it forms a deep violet color complex with Fe(2+) and has a broad absorbance peak centered at â¼562 nm. 1,10-ortho-phenanthroline develops an orange color complex with Fe(2+) (having an absorbance peak centered at â¼510 nm) and has been used to determine ferrous ion in glass. Both the methods are compared and the estimated redox ratio was found to be higher in the ferrozine method. The error limit of measurement has been determined as 0.012 and 0.023 for the ferrozine and 1,10-ortho-phenanthroline methods, respectively.
