hydronium;iron(3+);hexahydroxide;disulfate

Categories

Category name:

Dissociating, inorganic and non-toxic iron compounds

Justifications and discussions

Category definition:

The category comprises five soluble coagulant iron salts (ferric and ferrous chloride and ferrous and ferric sulphate and ferric chloride sulphate, including their various hydrated forms), ferrous and ferric hydroxide and Hydronium Jarosite

Category description:

There is no rationale to place the category members in a meaningful order.

Category rationale:

The Category hypothesis is that the iron compounds comprised are directly analogue iron III and II (ferric and ferrous) compounds, with counterions which are ubiquitous and do not require additional consideration. The formation of a Category is justified, on the basis of a self-consistent model of the behaviour and properties of these substances. All of these salts will dissociate in aqueous media under normal environmental conditions of pH, ambient temperature and dissolved oxygen, to the respective anions and kations, and then be subject to further change of oxidation and speciation state according to the conditions. The composition of this equilibrium depends on these conditions rather than the ferric or ferrous character of the original iron salt as the kations transform readily.
With regard to the physicochemical and toxicological property data sets the parent category members were not equal but due to the transformation equilibrium of the iron species a common view is considered meaningful. Thus these endpoints were included in the category in order to facilitate read across where applicable. Nonetheless the discussion and assessment of iron (II) and (III) are not identical.