engleski

Effect Of Urea On The Hydrolysis Of Fe3+ Ions In Aqueous Solutions At Elevated Temperature

The hydrolysis of 0.1 M FeCl3 or 0.1 M Fe(NO3)(3) solutions containing urea was investigated at elevated temperature. beta-FeOOH was the principal hydrolytical product of 0.1 M FeCl3 hydrolysis at 90 degrees C. Its structural stability was preserved up to pH 7.55 for initial concentration of 2 M urea. After the formation of alpha-FeOOH, the phase transformation beta-FeOOH --> alpha-Fe2O3, via dissolution, was accelerated. For the initial concentration of greater than or equal to 3 M urea, the formation of alpha-Fe2O3 and a small amount of alpha-FeOOH was observed. In the presence of nitrate anions, the mixtures of alpha-Fe2O3 and alpha-FeOOH were produced with tendency for the formation of alpha-Fe2O3 as the end product. In some samples, the presence of a small amount of gamma-FeOOH could be detected on the basis of IR bands at 1024 and 745 cm(-1). The Fe-57 Mossbauer spectra indicated that alpha-FeOOH and alpha-Fe2O3 particles were very small and probably not well-crystallized. The samples were also characterized with transmission electron microscopy. [References: 16]

Alpha-Fe2O3. Mossbauer spectroscopy. Infrared. Beta-FeOOH. Particles. Chloride.

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