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Aluminum hydroxide

CAS Number
21645-51-2
EC Number
244-492-7
Chemical Formula
AlH3O3
Molecular Weight
78.004 g/mol

Description

Aluminum hydroxide (CAS 21645-51-2 ), also sold as hydrated alumina, is an inorganic mineral compound used across industrial and pharmaceutical markets as a flame retardant, antacid active, and catalyst precursor. Its function shifts significantly by grade and particle size, making specification alignment critical at the sourcing stage. In plastics and polymer compounding, it acts as a halogen-free flame retardant and smoke suppressant. The material is incorporated into cable jacketing, flooring, and construction panels to meet fire safety standards. Pharmaceutical manufacturers use it as an active ingredient in antacid formulations where it neutralizes excess gastric acid. Sold historically under the brand Amphojel, it is used in OTC tablet and suspension products. In the paper and textile industries, it functions as a mordant and surface treatment agent, improving dye fixation and coating adhesion. Catalyst producers also use it as a precursor for alumina-based catalysts applied in refining and chemical synthesis. The product is supplied as a fine white powder, with particle size and surface area varying by intended application. Standard grades include USP and BP for pharmaceutical use, and technical or flame-retardant grades for industrial polymer applications. FCC -grade material is available for food-contact and food-additive applications. Contact us for supply of Aluminum hydroxide Request Quote

Other Names (Synonyms)

aluminium hydroxide | Hydrated alumina | Amphojel | aluminum hydrate | Dried aluminium hydroxide | Aluminum hydroxide, dried | Aluminium hydroxide, dried | Alu-Cap

Key Technical Features

  • High Purity Grade standard
  • Consistent Batch Quality
  • Full Regulatory & REACH Support
  • Global Logistics Network enabled

Physical Properties

Melting Point300 °C
Boiling Point2980°C[at 101 325 Pa]
Density2.42 g/cm³
Appearancewhite amorphous powder
ColorWhite
OdorOdorless
Formcolloidal suspension
Water Solubilityinsoluble
Vapor Pressure<0.1 hPa (20 °C)
Refractive IndexAverage refractive index: 1.57-1.59
pH8-9 (100g/l, H2O, 20℃)(slurry)
Log P-1.380 (est)

Safety & Handling

Warning
GHS07· Irritant

Hazard Statements

H315Causes skin irritation
H319Causes serious eye irritation
H335May cause respiratory irritation

Precautionary Statements

P261Avoid breathing dust/fume/gas/mist/vapours/spray.
P264Wash … thoroughly after handling.
P271Use only outdoors or in a well-ventilated area.
P280Wear protective gloves/protective clothing/eye protection/face protection.
P319Get medical advice/attention if you feel unwell.
P321Specific treatment (see … on this label).
P405Store locked up.
P501Dispose of contents/container in accordance with local regulations.
P265Wash … thoroughly after handling.
P352IF ON SKIN: Wash with plenty of water.
P340IF INHALED: Remove person to fresh air and keep comfortable for breathing.
P317Get emergency medical help.
P317If eye irritation persists: Get medical advice/attention. Get emergency medical help.
P364Take off contaminated clothing and wash it before reuse.
P233Store in a well-ventilated place. Keep container tightly closed.
P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.

Trade & Regulatory

HS Code28183000
Storage Class13 - Non Combustible Solids