Prussian Blue: Colours and Therapeutic Aspects

Abstract

The subject of this thesis is the description of the therapeutic aspects of Prussian blue towards heavy metal poisoning (Cs, Tl, radioactive).A remarkable example occurred recently in Italy (2015), as the water in Pietrasanta (Toscana) was found to be contaminated with thallium [1] [2] [3].Prussian blue has different chemical names, including: ferric ferrocyanide, ferrous ferricyanide, hexacyanoferrate (II) to iron (III) hexacyanoferrate (III) to iron (II), and ferric hexacyanoferrate. It is an intense blue pigment and tends towards black or dark purple when mixed with other oil colours.Prussian blue has been described with 2 forms, the soluble, KFe (II) [Fe (III) (CN) 6] and the insoluble form, Fe (III) 4 [Fe (II) (CN) 6] 3 · 6H2O; the name comes from historical reasons rather than by solubility connotations. Keggin and Miles suggested a face-centered cubic structure in which the high-iron spin and low-spin ferrocyanide are arranged in an octahedral structure linked to -NC and -CN units respectively with K + counter ion interstitial site. It lacks a quarter of hexacyanoferrate ions with the nitrogen site occupied instead by a cluster of water molecules coordinated to the site of the Fe (III) with other molecules of interstitial water.It is obtained by reaction between the potassium ferrocyanide and iron (III) ions; the colour is so intense and characteristic as to render this reaction suitable for the detection of iron or cyanides.The Prussian blue can also be used as a chelating agent and in the treatment for heavy metal poisoning, in particular it is used for patients who have ingested radioactive cesium or thallium (or even for the non-radioactive thallium) [4] [5].

Keywords: Prussian blue, Cesium, Thallium, Radioactive.