Aluminum oxide CAS#1344-28-1

PRODUCTS

Aluminum hydroxide CAS#21645-51-2

Product Properties

Aluminium hydroxide, with the chemical formula Al(OH)₃, is a white solid that is insoluble in water and soluble in acids or alkalis. It is a typical amphoteric hydroxide. When it is heated in air and dehydrated, it can be converted into aluminium oxide, which is of great significance for the production of aluminium oxide. Aluminium hydroxide can react with both acids to form salts and water, and with strong bases to form salts and water. Therefore, it is an amphoteric hydroxide. Due to its certain acidic properties, it can also be called aluminium acid (H₃AlO₃).

Quality index

Melting point	300℃
Boiling point	2980℃[at 101 325 Pa]
density	2.42 g/cm3 at 20 °C
bulk density	~90g/100 mL
vapor pressure	<0.1 hPa (20 °C)
refractive index	Average refractive index: 1.57-1.59
storage temp.	Store at +5°C to +30°C.
solubility	0.0015g/l
form	colloidal suspension
color	White
Specific Gravity	2.42
Odor	Odorless
PH Range	>7
PH	8-9 (100g/l, H2O, 20℃)(slurry)
Water Solubility	insoluble
Crystal Structure	Monoclinic
Merck	14,342
Solubility Product Constant (Ksp)	pKsp: 32.89
Exposure limits	ACGIH: TWA 1 mg/m3
Dielectric constant	2.2（Ambient）
Stability:	Stable. Incompatible with strong bases.
LogP	-1.380 (est)
CAS DataBase Reference	21645-51-2(CAS DataBase Reference)
EPA Substance Registry System	Aluminum hydroxide (21645-51-2)

Application

In chemical raw materials, because aluminium hydroxide can be produced on a large scale, the raw materials are abundant, the product purity is high, and it is easily soluble in acids and alkalis. Therefore, aluminium hydroxide is an important raw material for preparing aluminium salts, such as barium aluminate, aluminium sulfate, etc.
As a flame retardant, aluminium hydroxide powder has the functions of filling, flame retardancy, and smoke suppression, and it is non-toxic and harmless. It is usually regarded as an ideal flame retardant filler for plastics, unsaturated polyesters, rubber, and other organic polymers. The flame retardant mechanism of aluminium hydroxide is as follows: when the temperature exceeds 200°C, aluminium hydroxide begins to decompose endothermically and release three molecules of crystal water, and its decomposition rate is the highest at around 250°C. That is, this reaction is a strongly endothermic reaction, which can inhibit the temperature rise of the polymer, reduce its decomposition rate, and only produce water vapor without generating toxic and harmful gases.
In ceramics, aluminium hydroxide is calcined at a high temperature to obtain aluminium oxide. Aluminium oxide has high thermochemical stability, thermal strength, creep resistance, dielectric properties, and a low coefficient of thermal expansion, making it an important material for synthesizing ceramics. During the ceramic synthesis process, aluminium hydroxide activates and controls the crystallization process, thus achieving the control of the phase formation of the composite material.
In sewage treatment, in water, aluminium hydroxide mainly exists as Al(OH)₄⁻. It can precipitate toxic heavy metals in sewage through the method of coprecipitation, and then purify the water through filtration. Aluminium hydroxide also has a high specific surface area, which can adsorb colloids, suspended solids, dyes, organic substances, etc. in sewage on its surface.
In the pharmaceutical industry, aluminium hydroxide can neutralize gastric acid, and it is non-toxic and harmless. It is a traditional good medicine for treating stomach diseases. When aluminium hydroxide is used as an adjuvant drug, it can improve the immunogenicity of vaccines. Its mechanism of action is to adsorb antigens on the surface of aluminium hydroxide and release them slowly, so as to prolong the effectiveness of the medicine.
As a catalyst carrier, during the preparation of aluminium hydroxide, by controlling reaction conditions such as temperature, concentration, and pH of the reactants, the target products with different specific surface areas, pore volumes, pore structures, and crystal structures can be prepared. It can be effectively used as a catalyst carrier for the hydrogenation of unsaturated carbonyl compounds, the preparation of fullerenes, etc.
In the paper industry, aluminium hydroxide has high whiteness, ultra-fine particle size, and a complete crystal form, and it has strong compatibility with brighteners. When used as an additive for coatings and resins, it can effectively improve the whiteness, opacity, smoothness, and inkability of coated paper.