Combined Ferrite Treatment of Multi-Component Wastewaters

Background

The research teams of Bybik and Makarov (Bybik et al., 1979; Makarov et al., 2015), studying the kinetics of ferrite formation from the colloidal particles of iron (II) and (III) hydroxides during the chemical production of magnetic fluids, have observed some incubation period of ferritized particles crystallization, which is usually typical for the induction of autocatalytic reactions. Semenov (Semenov et al., 2005), while developing the technology for stabilizing long-term stored heavy metal hydroxide sludge, in order to reduce the metal ions “washout” during storage, have proposed to transform the hydroxide sludge into a more chemically stable oxide (ferrite) form. To do this, hydroxide sludge was subjected to preliminary dissolution in sulfuric acid with the subsequent introduction of alkaline chemicals, iron (II) sulfate, and previously obtained magnetite-containing sludge, and heating the mixture to 70–90°C, which ensured ferritization of the entire mass of the sludge. The positive effect of ferritized sludge additions on the process was explained only from the standpoint of improving of its technological properties, without explaining the mechanism of ferritization.