High Quality with Aluminium Hydroxide CAS 21645-51-2

• CAS No.: 21645-51-2
• Classification: Alumina
• Grade Standard: Industrial Grade
• Kind: Acidic Oxide
• Quality: First Class
• Transport Package: BGA
• Model NO.: 99%
• Specification: 25kg
• Origin: China
• Production Capacity: 500000 Bags/Month

Product Description

Appearance and properties: white amorphous powder
Density: 2.40g/cm3
Melting point: 300ºC
Water solubility: insoluble
Storage conditions: warehouse ventilated and dry at low temperature
Aluminum hydroxide reacts with acid: Al(OH)3+3HCl → AlCl3+3H2O
Al(OH)3+3H+ →Al3++3H2O
Aluminum hydroxide reacts with base: Al(OH)3+NaOH → Na[Al(OH)4]
Isomerization of aluminum hydroxide in an alkaline environment: Al(OH)3→HAlO2+H2O
Al(OH)3+OH-→AlO2-+2H2O

Thermal decomposition of aluminum hydroxide:
There are two types of ionization in aluminum hydroxide water:
1. Al(OH)3⇋Al3+ + 3OH- (basic ionization)
2. Al(OH)3+H2O⇋[Al(OH)4]-+H+ (acid ionization)
Among them [Al(OH)4]- is used to be written as AlO2- in middle school, but in fact this is wrong.
The so-called aluminum hydroxide actually refers to the hydrate of aluminum oxide. For example, the white colloidal precipitate obtained by adding ammonia water or weak base to the aluminum salt solution has variable water content and uneven composition, and is collectively referred to as hydrated alumina. Only by passing CO2 in the aluminate solution (containing Al(OH)4- ions) can real aluminum hydroxide be obtained.
Different from hydrated alumina, crystalline aluminum hydroxide is insoluble in acid, does not dehydrate when heated to 373K, and can be converted into aluminum metahydroxide AlO(OH) when heated at 573K for 2h.
Aluminum hydroxide is an amphoteric hydroxide. Due to its existence in two ionized forms, it is both a weak acid, which can have an acidic chemical formula H3AlO3, and a weak base, which can have a basic chemical formula Al(OH)3. Aluminum hydroxide is amphoteric and can react with both acids and bases.

The acidity of aluminum hydroxide is that it is a Lewis acid that can add OH- to reflect basicity
Al(OH)3 can produce two salts due to the existence of two ionizations: aluminum salts and metaaluminates:
1.Aluminum salts: AlCl3, KAl(SO4) 2 12H2O (alum), their aqueous solutions are acidic due to the hydrolysis of Al3+
2. Metaaluminate, NaAlO2, KAlO2, their aqueous solutions are alkaline: AlO- + 2H2O → Al(OH)3 + OH- When the two types of salts are mixed, a double hydrolysis reaction occurs, generating Al(OH)3 .
Al3+ + 3 AlO-+ 6H2O = 4Al(OH)3↓
Aluminum hydroxide mainly has four specifications: 325 mesh, 800 mesh, 1250 mesh and 5000 mesh. White powdery solid. Almost insoluble in water, it can condense suspended solids in water and adsorb pigments.
Security Information
Customs code: 2818300000
Hazard category code: R36
Safety Instructions: S26-S36
RTECS No.: BD0940000
Dangerous goods sign: Xi


The main purpose:
Aluminum hydroxide is the largest and most widely used inorganic flame retardant additive. As a flame retardant, aluminum hydroxide can not only be flame retardant, but also prevent smoke, no dripping, and no toxic gas. Therefore, it has been widely used, and the amount of use is increasing year by year. Scope of application: Thermosetting plastics, thermoplastics, synthetic rubber, coatings and building materials industries. At the same time, aluminum hydroxide is also the basic raw material of aluminum fluoride necessary for the electrolytic aluminum industry, and aluminum hydroxide is also widely used in this industry.