Reduction of aqueous potassium ferrate

Iron oxide is an impurity in various potash sources.  When the potassium carbonate/iron oxide mixture is heated to temperatures above ~550C, potassium ferrate is formed.  This gives a hexaco-ordinated, soluble iron species.  The species is highly coloured and leads to off-spec and undesirable colours.It would be desirable, for some applications, to reduce this ferrate to a ferrous species in order to eliminate the colour.  It is further advantageous to understand the family of reducing agents that are effective for this reduction.  Potential reducing agents include sulfite, sulfur, ascorbic acid, citric acid and formic acid.

The required experimentation would involve developing a testing protocol, and then performing a set of chemical reduction experiments in order to identify which reducing agents are suitable, and under what conditions.  Further, it is useful to understand the fate of the iron – does it remain in solution, or does it precipitate.

This project is suitable for a 4th year or MEng thesis.

For further information, contact Graeme Norval (

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