Wet Aluminum Hydroxide, also known as hydrated aluminum oxide or alumina trihydrate (ATH), is a white, gel-like or powdery inorganic compound with the chemical formula Al(OH)₃. It is widely used in industrial and pharmaceutical applications due to its flame-retardant properties, filler functionality, and acid-neutralizing capacity. As a flame retardant, it releases water upon heating, helping to suppress fires. In pharmaceuticals, it is commonly formulated as an antacid to relieve heartburn and indigestion. Additionally, wet aluminum hydroxide serves as a precursor in the production of high-purity alumina.
CAS number: 21645-51-2
Nickname: Aluminium Trihydrate,Aluminium Hydroxide,
Alumina Trihydrate, Alumina Hydrate,
Aluminum Tri Hydroxide,Aluminium Hydrate,
Aluminum Hydroxide, ATH Mineral.
Color/Appearance: White powder
Molecular formula: Al (OH) 3
Key Characteristics of Wet Aluminum Hydroxide (Al(OH)₃)
Chemical Composition: Wet aluminum hydroxide(PubChem) has the chemical formula Al(OH)₃. It appears as a white, odorless, gel-like or paste-like substance. It is insoluble in water and non-toxic, making it suitable for both industrial and pharmaceutical applications.
High Purity: The material typically contains ≥99% Al(OH)₃ with very low levels of impurities such as Fe₂O₃, SiO₂, and Na₂O. This makes it an ideal precursor for producing high-purity alumina (Al₂O₃).
Excellent Flame Retardancy: Wet aluminum hydroxide begins to decompose around 200–220°C, releasing water vapor that acts as a flame suppressant. It absorbs heat and dilutes combustible gases, making it a key component in halogen-free flame retardant (HFFR) formulations.
High Whiteness and Opacity: With its bright white appearance, it serves as an effective pigment or filler in plastics, rubber, coatings, and paper, enhancing opacity and brightness in end products.
Good Dispersibility and Surface Reactivity: The wet form offers excellent dispersibility in aqueous systems and interacts well with resins, additives, and polymers in composite materials.
Pharmaceutical Antacid Properties: In pharmaceutical applications, wet aluminum hydroxide functions as a neutralizing agent to relieve symptoms of heartburn, acid indigestion, and upset stomach.
Low Oil Absorption: This property ensures compatibility with polymer matrices while maintaining mechanical strength, especially in flame-retardant plastic formulations.
Environmentally Friendly: Wet aluminum hydroxide is halogen-free, non-toxic, and recyclable. It is widely used in eco-friendly and sustainable material applications.
Wet aluminum hydroxide is often used as a precursor for dried aluminum hydroxide in flame retardant and pharmaceutical applications.
Applications of Wet Aluminum Hydroxide (Al(OH)₃)
1. Flame Retardants
Wet aluminum hydroxide is widely used as a halogen-free flame retardant in polymer-based materials. When heated, it decomposes around 200°C, releasing water vapor that cools the material surface and suppresses flammable gas evolution. This makes it an ideal additive for enhancing fire safety.
Typical applications include:
- Insulation layers in wire and cable
- Flame-retardant plastics such as PE, EVA, and PVC
- Rubber compounds for hoses and gaskets
- Coatings for furniture, textiles, and building materials
2. Filler in Plastics, Rubber, and Paper
Due to its high whiteness, low oil absorption, and excellent dispersibility, wet aluminum hydroxide is used as a functional filler. It improves mechanical strength, enhances surface finish, and boosts thermal stability of the final product.
- Plastic masterbatches for automotive and electrical parts
- Rubber formulations including belts and seals
- Paper coatings to improve brightness and printability
- Paints and industrial coatings
3. Pharmaceuticals (Antacid Agent)
Pharmaceutical-grade wet aluminum hydroxide is a key ingredient in over-the-counter antacid products. It effectively neutralizes excess stomach acid and provides relief for conditions such as:
- Acid reflux and GERD
- Heartburn
- Indigestion and upset stomach
It is compliant with major pharmacopeias such as USP and EP and is safe for oral use.
4. Ceramics and High-Purity Alumina Production
Wet aluminum hydroxide serves as a primary raw material in producing high-purity calcined alumina (Al₂O₃), used in the manufacture of advanced ceramics, spark plugs, electrical insulators, and grinding media. Its consistent morphology and purity make it ideal for precision ceramic processing.
5. Water Treatment and Environmental Applications
Thanks to its chemical reactivity and high surface area, wet aluminum hydroxide is employed in several environmental fields:
- As a coagulant in wastewater treatment
- In flue gas desulfurization (FGD) systems
- For heavy metal adsorption and removal
It offers an eco-friendly solution that meets modern regulatory requirements.
6. Catalyst and Catalyst Support
After thermal treatment, wet aluminum hydroxide can be transformed into activated alumina, which is widely used as a catalyst or catalyst support in the chemical and petrochemical industries. Its large surface area and tailored porosity enhance catalytic activity and selectivity.
Need a deeper understanding of ATH’s chemical nature and why it’s ideal for flame retardancy? Explore What is Alumina Trihydrate (ATH) for full insights.
Specific Examples
Low-Smoke Halogen-Free Cable (LSHF Cable)
Wet aluminum hydroxide is used in LSHF cables as a flame retardant. It releases water vapor when heated, reducing heat and flammable gases to suppress fire and smoke. This helps cables meet fire safety standards such as IEC 60332 and UL 94 V-0.
Important Considerations
- Dry vs. Wet Form: While wet aluminum hydroxide contains free moisture, it can also be dried into powdered forms such as DH-65 or DH-50P to facilitate storage, transportation, and uniform blending in formulations.
- Chemical Reactivity: Its high reactivity makes it well-suited for various industrial chemical reactions and synthesis processes.
- Health and Safety: In excessive doses, or in individuals with impaired kidney function, aluminum hydroxide may cause adverse health effects such as seizures, osteomalacia (bone softening), or encephalopathy (neurological disorders).
Banlan provides a full range of aluminum oxide-based chemicals, including activated alumina, high-temperature calcined alumina, high-purity alumina, pseudo-boehmite, boehmite, catalyst carriers, fused alumina, and other alumina products. These materials serve critical applications in refractories, ceramics, abrasives, and electronics industries.
