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About Aluminium Nitrate

Aluminium nitrate most commonly exists in its hydrated crystal form, aluminium nitrate nonahydrate, Al(NO₃)₃·9H₂O. It is a white crystalline, water-soluble salt with a molecular weight of 375.15 g/mol. It melts at 73^oC and decomposes at 150^oC. It is an odourless material and will react explosively upon contact with organic compounds. Its solution is acidic and is a strong oxidising reagent. It can easily dissolve in water and ethanol but not in acetic acid and ethyl acetate.

Manufacturing Process

Contrary to aluminium chloride, it cannot be synthesised just by adding nitrates containing compounds (such as nitric acid) to aluminium metal. This is because aluminium will form a passivation layer, where there will be a creation of an outer layer on the metal to prevent further chemical reactions from occurring. Hence, aluminium nitrate is typically prepared by the addition of nitric acid to aluminium chloride. Nitrosyl chloride is generated as a byproduct which oozes out of the solution as a gas.

Aluminium nitrate can also be produced by mixing solution of lead nitrate with aluminium sulfate via a metathesis reaction. Insoluble lead sulfate precipitates out of the solution, giving a solution with aluminium nitrate.

Water Treatment & Coagulation

Aluminium Nitrate is used as a flocculant/coagulant in water-treatment processes to help aggregate fine particles, aiding in removal of turbidity, suspended solids and other impurities.

Dyeing, Textiles & Leather-Processing

In the textile and leather industries, Aluminium Nitrate serves as a mordant (to fix dyes) and is involved in leather tanning processes.

Chemical & Materials Intermediate

Aluminium Nitrate is used as a precursor or intermediate to other aluminium compounds (e.g., alumina), and in insulating paper, transformer core laminates, cathode-ray tubes, and metal-surface treatments.