CERIC HYDROXIDE

PRODUCT IDENTIFICATION

Ce(OH)₄

H.S. CODE

TOXICITY

SYNONYMS

CLASSIFICATION

Cerium compound, Catalyst

EXTRA NOTES

PHYSICAL AND CHEMICAL PROPERTIES

PHYSICAL STATE

AUTOIGNITION

NFPA RATINGS

REFRACTIVE INDEX

GENERAL DESCRIPTION & APPLICATIONS

http://www.osti.gov/
It has been known that Ce(III) forms a basic salt, because the precipitation of cerium is complete before the theoretical amount of caustic is added to the rare earth sait solution, but the composition of the basic salt of cerium has not been accurately investigated. Changes in pH, electric conductivity, and apparent volume of the precipitate as well as changes in the composition of the liquid and solid phases were investigated on the addition of NaOH to a dilute (0.025 gram-ion/liter) chloride or sulfate solution of cerium(III). All experiments were carried out in freshly distilled water under an atmosphere of nitrogen to exclude carbon dioxide. Oxygen was removed from the nitrcgen by bubbling through a pyrogallate solution to prevent the oxidation of cercus ion to ceric. It was found that in the system Ce/sub 2/(SO/sub 4/)/sub 3/- NaOH-H/sub 2/O an unstable basic salt Ce/sub 3/(OH)/sub 5/(SO/sub 4/)/sub 2/ is formed which is transformed to th e more stable sait Ce/sub 2/(OH)/sub 4/SO/sub 4/ on further addition of caustic (at n = 2 where n = the ratio of (NaOHI: (Ce/sup 3+/) in the starting mixture). At n = 2.5 the basic sulfate salt decomposes rapidly to cerous hydroxide which tenaciously retains a residual amourt of sulfate that can not be removed even with a two-fold excess of caustic (n = 6.0). Cerium(III) chloride first forms the unstable basic sait Ce/sub 2/(OH)/sub 5/Cl which is converted to the hydroxide on further addition of caustic. Cerium(IIl) hydroxide does not adsorb excess caustic from solution.

Local: Cerium is a metallic chemical element in group IIIb of periodic table; symbol Ce, soft, lustrous, ductile, iron-color metal with hexagonal or cubic crystalline structure; atomic number 58; atomic mass 140.12; melting point ca 799 C; boiling point ca 3,426 C; specific gravity 6.77 g/cm³ at 25 C; oxidation state +3 or +4; electronic config. [Xe]4f¹5d¹6s¹. It is the most abundant rare-earth element and the most reactive next to europium among the lanthanide group. Lanthanide (or lanthanoid) series are the group of rare-earth elements from lanthanum (atomic numbers 57) to 71; their chemical properties are similar to each other. The chemical properties of scandium and yttrium are also similar to the lanthanides; these group are often referred to "rare earth elements".

Cerium occurs chiefly in the minerals monazite and bastnaesite. The naturally occurring element is made up of the isotopes ¹³⁶Ce 0.193%, ¹³⁸Ce 0.250%, ¹⁴⁰Ce 88.58%, and ¹⁴²Ce 11.07% which is a radioactive alpha emitter having a half-life of 5×10¹⁵ years. Cerium is slightly harder than lead. It tarnishes rapidly in moist air but not in dry air. It oxidizes slowly in cold water and rapidly in hot water. It reacts rapidly with the solutions of alkalis and concentrated (or dilute) acids. Its oxidation valence is readily transferred form 3 to 4 if compressed or cooled. Its shell orbitals are relatively close between 4f and the outer. with Cerium of valence +3 is referred to as cerous, while with valence 4 is as ceric. Generally cerous salts are yellow to reddish while ceric slats are white. Minute particles of pure cerium or some iron-cerium alloy ignite if scratched and are used as the flint in cigarette and gas lighters. Cerium is used in making lamp mantles as incandescence is formed when burned. Cerium is allied to form malleable iron,  harder stainless steel, heat resistant magnesium and aluminium alloys and permanent magnets. It is also used as an opacifier and polisher in the glass industry, in cored carbon arcs to increase the brilliance especially for the motion picture industry, and as a liquid-liquid extraction agent to remove fission products from spent uranium fuel. Cerium compounds include;

• Ceric Oxide CeO₂ (CAS RN:1306-38-3): A pale-yellow to white powder; soluble in sulfuric acid, insoluble in dilute acid and water; used in ceramics and as a polish for optical glass. Catalyst for hydrocarbon cracking, styrene production and water-gas shift reaction. Thermal stabilizer for alumina and in chemical regenerating process.
• Ceric Sulfate Ce(SO₄)₂·xH₂O (CAS RN:13590-82-4): Yellow needles forming a basic salt with excess water; used in waterproofing, mildew-proofing, and in dyeing and printing textiles.
• Ceric Ammonium Nitrate (NH₄)₂Ce(NO₃)₆ (CAS RN: 16774-21-3): Oxidizer
• Ceric Ammonium Sulfate Ce(NH₄)₄(SO₄)₄ (CAS RN: 10378-47-9, Dihydrate): Oxidizer
• Ceric Hydroxide Ce(OH)₄ (CAS RN: 12014-56-1)
• Cerous Acetate Ce(OOCCH₃)₃·1.5H₂O (CAS RN: 537-00-8, Sesquihydrate)
• Cerous Bromide: CeBr₃ (CAS RN: 14457-87-5, )
• Cerous Carbonate Ce₂(CO₃)₃ (CAS RN: 537-01-9, 5838-16-7)
• Cerous Chloride CeCl₃ (CAS RN: 7790-86-5, 19423-76-8, 18618-55-8)
• Cerous Fluoride CeF₃: White hexagonal crystals, melting point 1460 C; used in arc carbons to increase the brilliance of carbon-arc lamps.
• Cerous Naphthenate: Used as drier/additive for paints, coatings and inks; catalyst for chemical reactions
• Cerous Nitrate Ce(NO₃)₃ (CAS RN:10294-41-4, Hydrate)
• Cerous Oxalate: Ce(C₂O₄)₃·xH₂O (CAS RN:139-42-4, 15750-47-7): Used in ceramics, glass, phosphors and pyrotechnics
• Cerous Perchlorate CeO₉Cl₃ (CAS RN: 14017-47-1)
• Cerous Phosphate CeH₂O₅P (CAS RN:13454-71-2)
• Cerous Silicide CeSi₂ (CAS RN:12014-85-6)
• Cerium Stearate Ce(C₁₈H₃₅O₂)₂ :White, waxy, inert powder, melting point 100-110 C; used in waterproofing compounds and drier for paint and ink.
• Cerous  Sulfide Ce₂S₃ (CAS RN:12014-93-6)

APPEARANCE

REO/TREO

99.0 - 99.99%

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