Aluminum hydroxide CAS #21645-51-2
Superior Flame Retardancy – Endothermic decomposition (1.17 kJ/g) suppresses fire and smoke (UL 94 V-0 compliant).
High Purity & Versatility – Adjustable morphology (1-80 μm) for ceramics, catalysts, and pharmaceuticals (>99.8% purity).
Effective Environmental Remediation – Removes fluoride (15 mg/g) and neutralizes acid mine drainage.
Pharmaceutical-Grade Safety – Non-toxic antacid and vaccine adjuvant (NLRP3 inflammasome activation).
Controlled Thermal Conversion – Precursor to high-performance alumina (γ-Al₂O₃) for industrial processes.
Aluminum hydroxide (chemical formula Al(OH)₃) appears as a white crystalline powder that is water-insoluble but dissolves readily in both acidic and basic solutions, characteristic of amphoteric hydroxides. When heated in air, it undergoes dehydration to form aluminum oxide, making it an important material in alumina manufacturing.
This compound demonstrates amphoteric behavior by reacting with acids to yield salts and water, and similarly reacting with strong bases to produce salts and water. Due to its weakly acidic nature, it may alternatively be referred to as aluminic acid (H₃AlO₃). However, its actual reaction with bases results in the formation of tetrahydroxyaluminate ions ([Al(OH)₄]⁻). Consequently, it is more commonly classified as aluminum hydroxide monohydrate (HAlO₂·H₂O).
Aluminum Hydroxide (Al(OH)₃) is a multifunctional inorganic compound typically appearing as a white crystalline powder with a Mohs hardness of 2.5-3.5. Its water insolubility (solubility: <0.1 mg/mL at 20°C) contrasts with its high reactivity in acidic/alkaline media, a hallmark of amphoteric hydroxides. When calcined above 200°C, it undergoes controlled dehydration to γ-alumina (Al₂O₃), serving as the primary feedstock for aluminum metal production via the Hall-Héroult process.
Advanced Technical Parameters
Property | Technical Specification |
BET Surface Area | 3-40 m²/g (adjustable via precipitation) |
Oil Absorption | 45-65 mL/100g |
Dielectric Constant | 6.5-7.2 (1 MHz) |
Decomposition Temp | 180°C (onset), 300°C (complete) |
Particle Morphology | Hexagonal platelets (1-80 μm), spherical nanoforms |
Industrial Applications & Innovations
Advanced Flame Retardancy
Mechanism: Endothermic decomposition (ΔH: 1.17 kJ/g) releases H₂O vapor, suppressing smoke density by >60%
Formulations: UL 94 V-0 compliant composites (60-65% loading in EVA cables)
Pharmaceutical Engineering
Antacid: Neutralizes HCl with minimal gas production (pH 6.5-7.5)
Vaccine Adjuvant: Enhances antigen presentation via NLRP3 inflammasome activation
Ceramic & Catalysis
Catalyst Carrier: High-purity (>99.8%) forms for hydrodesulfurization
Advanced Ceramics: Precursor for transparent alumina (in-line transmittance >80% at 640 nm)
Environmental Remediation
Fluoride Removal: Adsorption capacity up to 15 mg/g at pH 5.5
Acid Mine Drainage: Neutralizes sulfuric acid while precipitating heavy metals
Packaging & Logistics
Containment: Triple-layer kraft bags (25kg), polyethylene-lined bulk bags (1,000kg), ISO tank containers
Shelf Life: 24 months when stored <30°C/RH<50% (avoid CO₂ exposure)
Handling: Class 9 IMDG (Not Restricted); Dust explosion class St-1 (Kst<200 bar·m/s)
