Synthesis and characterization of iron oxide pigments through the method of the forced hydrolysis of inorganic salts

• Effect of the precursor and temperature forced hydrolysis in size and phase obtained.
• Methodology clean without residue, costly steps or special conditions (pressure, atmosphere).
• Phase identification by XRD and Raman spectrum.
• Iron oxides as inorganic synthetic pigments without the need for chemical modification.

Iron oxide hydroxides were synthesized through forced hydrolysis of iron (III) chloride hexahydrate and iron (III) nitrate nonahydrate that as a function of temperature yield different phases characterized by their colors. The tonalities were related to the chemical composition as well as particle size as shown through energy dispersive spectroscopy, thermogravimetric analysis and dynamic light scattering. Iron chloride yielded Akaganèite with different opaque yellow tonalities and a mean particle size of196 (50 °C), 253 (70 °C), 235 (90 °C) and 170 nm (110 °C). The nitrate precursor yielded Goethite with yellow tonalities and particle size of 360 (60 °C) and 318 nm (70 °C), and Hematite with red tonalities and particle size of 262 (90 °C) and 261 nm (110 °C). The test dispersion and coloring of the white paint (water-based) showed an effective coating capacity, chemical and physical stability of the dispersant and iron pigments.