A study of the influence of synthesis parameters on the physicochemical properties of iron pigments produced from waste iron sulfate

Abstract

The work presents a two-step method of iron red synthesis based on waste iron(II) sulfate. The synthesis was carried out using purified waste iron sulfate from titanium dioxide production. The study investigated the influence of factors such as temperature, pressure, concentration of solutions and synthesis time on the physicochemical properties of pigments. Obtained pigments were tested with instrumental analytical methods, e.g. X-ray Diffraction or BET surface area analysis. The pigments were analyzed for color, particle size as well as for oil number. The results of the research showed a change in the physicochemical properties of the obtained pigments depending on the conditions of synthesis. It was shown that increasing the synthesis time in most cases increased the degree of crystallization of hematite in the pigments. High specific surface area, low agglomeration of pigments or low oil absorption were directly related to the crystallinity of the pigments obtained. Laboratory pigments have been found to be different from commercial pigments. The difference in properties speaks in favor of synthesized materials.

Studies of the Morphology of Hematite Synthesized from Waste Iron Sulfate

“…Samples synthesized at pH = 10 are characterized by visible cubic particle shapes with small particle sizes, confirming the XRD and DLS results. The same cubic particle texture has been observed in previous studies [50] (Figure 9). For samples synthesized at pH = 12, we see a rather irregular particle texture.…”

“…This scale is based on the theory of opposing colors, assuming that receptors in the human eye perceive colors as pairs of opposites. Designed in this way, the scale allows a given color to be placed in three-dimensional space, using three values-L, a, and b-to describe each color [50,74].…”

“…Previous studies [50][51][52] have found that synthesized pigments based on waste iron sulfate differ significantly from commercially available pigments synthesized based on pure substances. Studies have investigated the effects of the change in pressure, time of the reaction, and concentration of iron salt.…”

“…sis to 170 °C, shortening the time to a range of 1-3 h. In some samples synthesized from 14% solutions in 20 bar for 1, 2, or 3 h for the first time, interesting cubic-shaped particles were observed [50].…”

“…At the same time, increasing the synthesis time causes the material particles to show higher agglomeration. It is also worth mentioning that the use of microwave-based reactions allows for a significant decrease in the temperature of synthesis to 170 • C, shortening the time to a range of 1-3 h. In some samples synthesized from 14% solutions in 20 bar for 1, 2, or 3 h for the first time, interesting cubic-shaped particles were observed [50].…”