Chromic Oxide (CI 77288) is a chemical compound, a synthetic dye, dichromium trioxide, chemically classified as an inorganic color. This pigment is widely used in various industrial and cosmetic applications due to its color properties and stability.
Chemical Name
Chemical Industrial Synthesis Process
- Preparation of reagents. The main raw materials include sodium dichromate (Na₂Cr₂O₇) and sulfuric acid (H₂SO₄).
- Synthesis of chromium (III) oxide. The production of Chromic Oxide begins with the reduction of sodium dichromate in an acidic solution. This process occurs by adding concentrated sulfuric acid, which reduces sodium dichromate to chromium (III) oxide.
- Filtration. The resulting suspension is filtered to separate the solid chromium (III) oxide from the acidic solution.
- Washing. The chromium (III) oxide is washed with deionized water to remove any soluble impurities.
- Drying. The washed chromium (III) oxide is dried at controlled temperatures to remove residual moisture and obtain a dry powder.
- Grinding. The dried chromium (III) oxide is ground to obtain a fine and uniform powder. This step may involve the use of ball mills or other grinding machinery.
- Classification. The dried powder is classified to ensure a uniform particle size. This step may involve sieving or the use of air classifiers.
- Stabilization. The Chromic Oxide powder is stabilized to ensure its stability during transportation and storage, preventing aggregation and degradation.
- Quality control. The Chromic Oxide undergoes rigorous quality testing to ensure it meets standards for purity, color intensity, and safety. These tests include chemical analysis, spectroscopy, and physical tests to determine particle size and rheological properties.
What it is used for and where
Cosmetics
Restricted cosmetic ingredient as IV/129 a Relevant Item in the Annexes of the European Cosmetics Regulation 1223/2009. Wording of conditions of use and warnings free from chromate ion
Cosmetics - INCI Functions
- Colorant. This ingredient has the function of colouring the solution in which it is inserted in a temporary, semi-permanent or permanent manner, either alone or in the presence of the complementary components added for colouring.
Chromic Oxide is used in cosmetic products such as eyeshadows, eyeliners, and nail polishes due to its intense green color and high opacity.
Industrial Applications
Paints and Coatings: In the paint industry, chromium (III) oxide is used to achieve deep green shades and enhance UV and weather resistance. Its stability makes it ideal for decorative and protective coatings.
Plastics and Polymers: This pigment is employed in the production of plastics and polymers to improve color uniformity and resistance to degradation from UV light and heat.
Ceramics and Glass: Chromic Oxide is used in the production of ceramics and glass to achieve stable and long-lasting green colors. It is particularly valued for its resistance to melting and high-temperature firing.
Inks: The pigment is also used in printing inks to produce intense and durable green colors, ensuring sharp and high-quality prints.
Safety
Chromic Oxide is generally considered safe for use in consumer products when handled according to proper safety procedures. It is important to avoid inhalation of the powder and minimize direct contact with skin and eyes. Although chromium (III) oxide is less toxic than other chromium compounds, environmental considerations include controlling emissions during production and ensuring proper waste disposal.
Molecular Formula Cr2O3
Molecular Weight 151.990 g/mol
CAS 1308-38-9
EC number 215-160-9
UNII X5Z09SU859
DTXSID4043721
Synonyms:
Pigment Green 17
Chromic oxide
Chromia
Chrome Green
Chromium sesquioxide
Dichromium trioxide
Chromic Oxide 
Sodium dichromate
