Aluminium Hydroxide

As is known to the majority of the individuals, aluminium is a naturally available mineral while aluminium hydroxide comes in the form of an antacid. It is suitable for treating upset stomach, acid indigestion, heartburn and sour stomach. You can also use it for reducing the levels of phosphate in people suffering from kidney problems. The antacid might even be suitable for other non-medicinal purposes.

For the ones who do not have any idea about what is aluminium hydroxide, it is also known as Aluminic Hydroxide, Aluminium (III) Hydroxide or Aluminic Acid. It is the chemical name of aluminium and just like all the other varieties of metal carbonates, sulfates and hydroxides. It is found naturally as mineral gibbsite along with its polymorphs called bayerite, doyleite and nordstrandite.

Properties of Aluminum Hydroxide

Coming to the properties of aluminium hydroxide, its density is 2.42 g/cm3, and its melting point is 300 degree Celsius. It is an amorphous powder in white colour and is insoluble in water. However, it is soluble in acidic and alkaline solutions. Aluminium hydroxide molar mass is 78.0036.

Aluminium hydroxide that needs to be used commercially is manufactured using the Bayer procedure. The process involves dissolving bauxite in a solution of sodium hydroxide at 270 degree Celsius. 

Once the procedure is completed, waste removal is carried out, leaving the solution of sodium aluminate to precipitate. The mineral obtained through the precipitation is called aluminium hydroxide. Calcination is the process used for obtaining aluminium oxide or alumina from aluminium hydroxide.  

Aluminum Hydroxide Structure

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The image depicts the structure of Aluminium hydroxide. 

Once you are aware of aluminium hydroxide properties, it is time for you to get a clear understanding of the chemical formula of aluminium hydroxide and aluminium hydroxide structure. 

Aluminium Hydroxide formula is Al OH3. It goes like this:

Al OH3 acid or base + 3 H – Al+3 + H2O (I)

Al (OH)3 + OH- - AlO2- + H2O (II)

The typical structure of aluminium hydroxide consists of the bonds of hydrogen and dual covers of aluminium ions and hydroxyl groups. These occupy around two-third of the octahedral holes available within the two layers. The amphoteric Gibbsite works in the form of a Bronsted-Lowry base for yielding a certain salt through the pick-up of hydrogen acids and the neutralization of the same. A reaction follows the procedure, which is:

3 HCl + Al (OH)3- AlCl3 + 3 H2O


It is not necessary to prepare aluminium hydroxide as it is present in huge abundance in different geological systems. Nevertheless, it is produced using the sintering and Bayer procedures for obtaining alumina from mineral bauxite. Therefore, 97% of aluminium hydroxide found in the world comes from the treatment of caustic soda and bauxite. The process yields sodium aluminate, which is further decomposed using the stirring procedure for obtaining aluminium hydroxide. The formula goes like this:

NaAl (OH)4 – Al (OH)3 + NaOH

There are other procedures also used for obtaining aluminium hydroxide, and these include Sol-gel or micro-emulsion and hydrothermal procedures. Using these procedures can help in generating aluminium hydroxide with higher levels of purity.

Aluminium Hydroxide Uses

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The image depicts the use of aluminium hydroxide. 

There are a plethora of uses of aluminium hydroxide in the chemical industry. The pharmaceutical and chemical uses of aluminium hydroxide include:

  • You can use it in the form of an antacid for treating ulcers and gastritis.

  • You can also use it as an additive in different vaccines.

  • Aluminium hydroxide also works in the form of an excipient during the process of manufacturing certain drugs.

  • The most common use of this formula is in the form of a raw material in the manufacture of aluminium oxide or alumina which further helps in the production of aluminium metal.

  • It is used in gel form.

  • As a filler in different cosmetics.

  • For the manufacture of activated alumina.

  • In the form of a chemical intermediate.

  • Aluminium hydroxide is in use as an additive in glass for increasing thermal shock resistance.

  • As a flame retardant and soft abrasive for plastics.

  • It is also used on a very wide scale in different water-resistant fabrics and the manufacture of paper.

Aluminum Hydroxide Side Effects

There are large-scale aluminium hydroxide side effects that users need to be aware of. High concentrations of the same can cause a lot of health damages. It might even damage the lungs and result in allergic reactions like swelling of the tongue, lips, throat and face; hives and breathing difficulty. Other side effects of using aluminium hydroxide include:

  • Pain while urinating

  • Severe pain in the stomach or constipation

  • Appetite loss

  • Tiredness and muscle weakness

  • Tarry or bloody stools

  • Coughing blood

  • Vomiting

  • Extreme drowsiness

If you witness any of these side effects, you must get emergency help as soon as possible. Even better, consult your healthcare professional before taking anything with high concentrations of the mineral.

FAQ (Frequently Asked Questions)

1. What is the Formula of Aluminium Hydroxide?

Aluminium Hydroxide formula is Al (OH)3. The molecule formation takes place with 3 hydroxyl anions or CO3-2 and aluminium cation or Al+3. Aluminium hydroxide structure is completely based on the mineral from which it is extracted mainly because the ions tend to show varied arrangements. Majority of the mineral lattice is orthorhombic or hexagonal.

2. What is Aluminium Hydroxide Gel?

Aluminium hydroxide gel can be defined as the suspension of the amorphetic aluminium hydroxide. The gel form of the mineral contains partial carbon substitutes. The gel form might also contain glycerin, peppermint oil, saccharin, sucrose and sorbitol along with various other flavours. The gel can also contain proper amounts of different antimicrobial elements. It is mainly used for the treatments of excessive stomach acid conditions like heartburn, acid indigestion and upset stomach. It works better than capsules or tablets.

The gel is prepared through the precipitation of the ethanolic solutions of aluminium chloride. Primary amines like octylamine, propylamine and dodecylamine are also added. These serve in the form of proton acceptors making precipitation a possibility during hydrolysis reaction.