Formation and Crystallization of Fe(III) Hydroxides. Influence of precipitation temperature and the nature of the starting Fe(III) salt on Fe(III) hydroxide crystallization in alkaline medium

Abstract

It is shown that amorphous precipitates of Fe(III) hydroxides are composed of two phases, namely weakly magnetic primary particles and ferrimagnetic fine‐grained particles. The relative proportion of the two phases, the type of phase transitions and the rate of amorphous precipitate crystallization during the ageing process are determined by the precipitation temperature. The crystallization of Fe(III) hydroxides during the ageing in mother liquors occurs by the “oriented growth” mechanism.

Production of ferrihydrite and schwertmannite using a microjet mixer device

“…specific surface area, crystallisation degree and primary particle diameter, were observed. This was caused by metastability of these agglomerated structures and the low speed of approach to equilibrium characteristic for ferric oxides (Penth, 2000;Goni-Elizalde and Garcia-Clavel, 1990;Krivoruchko et al, 1983;Šolcová et al, 1985;Waychunas et al, 2005). However, there was a small and for all experiments detected decrease in agglomerate particle size what is attributed to a slowly establishing equilibrium.…”

Tailoring Photocatalytic Activity of TiO2 Nanosheets by 57Fe

“…Thus, it may be concluded that the iron in the sample TIG-800-SUR is present predominantly in the form of very fine nanometer sized particles of a compound in which iron is surrounded similarly like in α-Fe 2 O 3 . Such behavior was described as typical for substances obtained by precipitation of Fe 3+ salts by alkalines or ammonia from aqueous solutions and in the chemical literature are denoted as amorphous hydrated iron­(III)-oxide gels. − …”