Iron Oxide Yellow

Iron Oxide Yellow

Iron oxide yellow is a commonly used inorganic yellow pigment, chemically composed ofHydrated iron(III) oxide (FeO(OH)·nH₂O)OrHematite (FeOOH)Excellent weather resistance, lightfastness, and chemical stability, widely used in coatings, building materials, plastics, papermaking, and other fields.

Basic Features

• Chemical FormulaFeOOH (hydroxide iron) or Fe₂O₃·H₂O (hydrated iron oxide).

• ColorGolden yellow to brown yellow, the specific hue depends on particle size and crystal form.

• Stability：

• UV and alkali resistant, but may dissolve in strong acids.

• Poor heat resistance (starts to dehydrate and transform into iron oxide red Fe₂O₃ above 180°C).

• Insoluble in water and ethanol, non-toxic and environmentally friendly.

• Form （注：由于“形态”一词在商业语境中较为抽象，直接翻译为“Form”可能不够精确。但根据要求，这里未提供更多上下文信息，因此按照一般商业用语进行了翻译。）Fine powder, usually in needle-like or spherical particles.

2. Preparation Method

Hydrogenation precipitation method (commonly used)

• Ferrous sulfate (FeSO₄) reacts with alkali (NaOH) to produce FeOOH upon oxidation with air.

  $${\text{FeSO}}_4+2\text{NaOH}+{\text{O}}_2\to 2\text{FeOOH}+{\text{Na}}_2{\text{SO}}_4+{\text{H}}_2\text{O}$$

• Adjustable pH, temperature, and oxidation rate to control color depth.

(2) Penniman-Zoph Process (Continuous Oxidation Method)

• Iron filings + nitric acid catalytic oxidation, suitable for mass production.

(3) Purification of Natural Minerals

• Magnetite (Goethite, α-FeOOH) grinding and purification; however, the purity is low and the color is dark.

3. Main Applications

• Construction Industry：

• Color concrete, cement bricks, road coatings, exterior wall putty, etc.

• Paints & Coatings：

• Outdoor Paint (UV-resistant), Anti-rust Paint, Road Marking Paint.

• Plastic & Rubber：

• Yellow coloring agent for PVC, PE, and rubber products.

• Paper & Ink：

• For packaging paper, decorative paper, and printing inks.

• Cosmetics：

• Iron oxide yellow meeting food-grade standards is suitable for eyeshadows, foundations, etc. (requires high purity).

4. Categories & Models

• By hueLemon yellow, medium yellow, deep yellow, etc. (depending on particle size and crystal type).

• Purity by percentage：

• Industrial grade (90-95%), Pigment grade (96%+), Food grade (99%+, low heavy metals).

• International Pigment Index：PY42（Pigment Yellow 42）。

Common Models：

• China Standard: 313, 920

• BASF: Sicotan® Yellow

• Lanxess: Bayferrox® 3910

5. Comparison with Iron Oxide Red

6. Important Notes

• Temperature-sensitiveAt high temperatures, it will dehydrate and turn red (→ Fe₂O₃); avoid using for high-temperature processing materials.

• DispersiveWell-dispersed in plastic or paint to prevent agglomeration.

• StorageSealed to prevent moisture, avoid contact with strong acids.

Iron oxide yellow is an ideal choice for replacing toxic pigments like cadmium yellow and chrome yellow due to its environmental friendliness, low cost, and excellent weather resistance.