Iron oxide black (E 172, synonym CI pigment black 11, three oxidation four iron, black iron oxide, two iron oxide, magnetite, color index 77499) and active substance iron (II, III) oxide (International pure Federation Applied Chemistry (IUPAC) name, chemical digest (CAS) number 1317-61-9, molecular FeO Fe2O3, molecular weight 231.55).
Iron oxide black is prepared by chemical synthesis of iron oxide yellow (FeO (OH)) or iron oxide red (Fe 2 O 3) and / or iron sulfate (II), which is converted / reacted (precipitation process) in the presence of pure oxygen and caustic soda.
Iron oxide black is a black powder with a relative density of about 4.6 kg / L and an apparent density of 0.7 kg / L. It is insoluble in water and organic solvents and soluble in inorganic acids.
The typical composition of the additives is as follows: iron oxide (II, III) 98.4%, sodium sulfate 0.2%, water 0.4%, alumina 0.5%, Magnesium Oxide 0.5%.
The content of five batches of iron oxide black.12 were analyzed in accordance with the specification (iron oxide black expressed as iron: iron: 68.5-70.9%; water-soluble salt: 0.09-0.13%; arsenic: <1 mg / kg; cadmium: <1mg / kg; chromium: 25-58mg / kg; copper: 6-31mg / kg; Pb: < < = >; nickel: Zinc