Hazard
Toxic by ingestion and inhalation.
Potential Exposure
Chromium(III) oxide is used as a paint pigment, a fixative for certain textile dyes; in the manufacture of chromium; and a catalyst.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a Medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit
Shipping
UN3086 Toxic solids, oxidizing, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, 5.1-Oxidizer. Technical Name Required. Spill Handling: Evacuate persons not wearing protective equipment from the danger area of spill or leak until cleanup is complete. Remove all ignition sources. Collect powdered material in the most convenient and safe manner and deposit in sealed containers. Ventilate area after clean-up is complete. It may be necessary to contain and dispose of this chemical as a hazardous waste. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters. Contact your local or federal environmental protection agency for specific recommendations. If employees are required to clean-up spills, they must be properly trained and equipped. OSHA 1910.120(q) may be applicable.
Incompatibilities
A strong oxidizer. Contact with reducing agents; organics, and combustibles may be violent
Physical properties
Green hexagonal crystal system; corundum type structure; density 5.22 g/cm3; melts at 2,330°C; vaporizes above 3,000°C; insoluble in water and alcohol.
Definition
chromium sesquioxide: A green crystallinewater-insoluble salt, Cr2O3; r.d. 5.21;m.p. 2435°C; b.p. 4000°C. It is obtainedby heating chromium in astream of oxygen or by heating ammoniumdichromate. The industrialpreparation is by reduction ofsodium dichromate with carbon.Chromium(III) oxide is amphoteric,dissolving in acids to give chromium(III) ions and in concentratedsolutions of alkalis to give chromites.It is used as a green pigment in glass,porcelain, and oil paint.
General Description
Chromium (III) oxide is a chromium complex in which the chromium ion is in +3 oxidation state. The synthesis of its sub-micron powder has been reported.? The IR and Raman spectra of chromium (III) oxide have been studied.? The impact of adding lysozyme on the stability of chromium (III) oxide (Cr2O3) suspension has been evaluated.?
Flammability and Explosibility
Notclassified
Toxicology
Chromium(III) oxide, which forms the basis of chromium oxide pigments, crystallizes in a corundum lattice. Chromium oxide green pigments (Cr2O3, C.I. Pigment Green 17) contain only trivalent chrome. Acute toxicity: rat, oral, LD50>10 000 mg/kg.
storage
(1) Color Code—Blue: Health Hazard/Poison:Store in a secure poison location. (2) Color Code—Yellow:Reactive Hazard; Store in a location separate from othermaterials, especially flammables and combustibles.Chromium(III) oxide must be stored to avoid contact withstrong oxidizers (such as chlorine, bromine, and fluorine),glycerol, and oxygen difluoride, since violent reactionsoccur. A regulated, marked area should be establishedwhere chromium(III) oxide is handled, used, or stored.Store in tightly closed containers in a cool, well-ventilatedarea.
Properties and Applications
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TEST ITEMS
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SPECIFICATION
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APPEARANCE
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GREEN POWDER
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CONTENT OF
Cr
2
O
3
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85% min
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SHADE
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YELLOWISH
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HYDROTROPE
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0.5% max
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OIL ABSORPTION
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25% max
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RESIDUE ON 45 MESH
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0.1% max
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WATER SOLUBLE
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0.3% max
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VOLATITE 105 °C
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0.05% max
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TINTING STRENGTH
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95-100 %
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pH VALUE OF AQUEOUS SUSPENSION
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5-8
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Structure and conformation
Chromium oxide is a dense, crystalline material, density 5.2 g/cm3, of the corundum type. It is quite hard-abut 9 on the Moh scale-which makes it a good grinding material, but too abrasive for many pigment applications. The particle size depends on the manufacturing process, but it is distributed around mean values in the range 0.5-0.6 μm. The refractive index of chromium oxide is quite high, 2.5, which is almost as high as that of rutile TiO2, 2.7. Chromium oxide pigments are green with an olive green tint. Small particles are lighter green with a yellowish hue, whereas larger particles are darker, with a bluish tint. Chromium oxide pigments are very inert materials with outstanding lightfastness and excellent resistance to acids, alkalis, and high temperatures.
Toxics Screening Level
The initial threshold screening level (ITSL) for chromium Ill oxide is 0.5 μg/m3 based on a 24-hour averaging time.
