Brown iron oxide, also known as brown iron oxide or iron oxide brown, has the following chemical properties and uses:

Chemical properties

Appearance and color: Brown iron oxide is a reddish-brown powder, odorless and tasteless.
Solubility: It has a very low solubility in water and is almost insoluble in water, but it can be easily soluble in boiling hydrochloric acid.
Chemical composition: Brown iron oxide is mainly composed of red iron oxide (Fe₂O₃), black iron oxide (which may contain complex components such as Fe₃O₄ or FeO·Fe₂O₃), and yellow iron oxide (FeO(OH) or Fe₂O₃·H₂O, etc.) mixed in a certain proportion, of which Fe₂O₃ is its main component.
Stability: Brown iron oxide has good light resistance and alkali resistance, and is not easily affected by external environmental factors and changes in properties.

Uses

Pigments and colorants:

• Due to its bright color and good hiding power, brown iron oxide is widely used as a pigment or colorant in industries such as paints, inks, rubber, and plastics.
• In architectural coatings, such as cement, bricks and tiles, concrete, etc., brown iron oxide can enhance its decorative and visual effects.

Catalyst: Brown iron oxide can act as a catalyst in certain chemical reactions to promote the reaction.
Polishing agent: It can be used as a polishing agent for glass, gemstones, and metals to help improve the gloss and surface quality of these materials.
Magnetic materials: Because they contain iron, brown iron oxide can also be used to make magnetic materials.
Other applications:

• In cosmetics, brown iron oxide is often used as a colorant for products such as eye shadow, lipstick, and blush.
• In the food industry, it can be used as a food additive, such as sauces, biscuits, and pastries, to adjust the color of food and increase appetite. However, it is necessary to ensure that food safety standards are met.
• In the pharmaceutical field, brown iron oxide also has applications, such as pigment marking, capsule preparations, and improvement of drug appearance.

In summary, brown iron oxide plays an important role in many industries due to its unique chemical properties and wide range of applications.