What is aluminum hydroxide?

Aluminum hydroxide

In order to understand the definition of aluminum hydroxide, it is necessary to know what aluminum is . This is a type of metallic element found on the periodic table and is represented by the word “Al.” It is one of the most common elements that can be found in nature and in various compounds. Aluminum can be found as a hydroxide , which at the same time represents the most stable form in which this metal can be found under normal conditions.

Aluminum hydroxide What is it, characteristics, properties, structure, risksWhat is aluminum hydroxide?

The aluminum hydroxide is one of the forms more stable in which can find the aluminum . In nature it can be found under the name of gibbsite mineral and is a fundamental part of bauxite .

  • Aluminum Hydroxide Characteristics
  • Structure
  • Formula
  • Nomenclature
  •  Aluminum Hydroxide Physical Properties
  • Chemical properties
  • Obtaining
  • What is it for
  • How is it taken
  • Aluminum hydroxide benefits
  • Importance in pregnancy
  • Risks

Aluminum Hydroxide Characteristics

Among its main characteristics are the following:

  • Aluminum hydroxide is characterized by being polymorphic and for this reason, it can be found in four different forms: gibbsite , nordstrandite , bayerite and doyleite .
  • Aluminum hydroxide is an inorganic compound that contains aluminum as its main component.
  • It is a type of inorganic salt which is used as an antacid .
  • It is commonly known as milk of magnesia .
  • It is widely used in people who have heartburn problems as it has the ability to neutralize acids.
  • As a medicine , it can be found in the form of pills , liquids, and chews .


The aluminum hydroxide molecule is formed by the aluminum cation Al + 3 and by three hydroxyl anions CO3-2 in its structure. The structure of the aluminum hydroxide framework always depends on the mineral from which it is extracted, this because the ions have different dispositions. Most of the network that is part of its structure is of the hexagonal or orthorhombic type . It is a hydroxide that also has 1 aluminum atom , 3 oxygen atoms and 3 hydrogen atoms in its structure .


The chemical formula for aluminum hydroxide is Al (OH) 3.


The nomenclature of aluminum hydroxide is established as follows:

  • Systematic nomenclature : it is named as aluminum trihydroxide .
  • Nomenclature stock : is known as aluminum hydroxide.
  • Traditional nomenclature : in this type of nomenclature it is called as aluminum hydroxide.

 Aluminum Hydroxide Physical Properties

Among its most relevant physical properties are the following:

  • Aluminum hydroxide is a white amorphous solid and odorless . Its density is 2.42 g mL-1.
  • The melting point of this aluminum hydroxide is 300ºC.
  • It is insoluble in water and ethanol, but it can be soluble in acids and alkaline solutions .
  • The purified aluminum hydroxide is in the form of a voluminous powder, is white in color and has a density of approximately 2.42 g per ml.
  • It has a molar mass of 0036.
  • Its molecular weight is 0.
  • It has a density relative to the water in a ratio of 2:42

Chemical properties

Its most relevant properties are:

  • Aluminum hydroxide is an amphoteric compound , this means that the substance has a series of basic or acidic characteristics and for this reason aluminum hydroxide is soluble in two solutions: acids or alkalis .
  • It is an electrical insulator , that is, it is incapable of conducting electricity, and it also has a relatively high thermal conductivity .
  • When it is in its crystalline form, it has a great hardness that makes it suitable as an abrasive .
  • It cannot be dissolved in water, but it can be dissolved in bases and acids .
  • When in contact with water for long periods of time, it can produce gels and absorb acids and carbon dioxide at the same time .


Aluminum hydroxide can, first, be found freely in nature as the mineral gibbsite . The main method by which aluminum hydroxide can be obtained is from the extraction of the mineral bauxite to which a process known as Bayer is applied , whose main objective is to achieve a separation between the hydroxides of aluminum from bauxite , the silica that become impure and iron oxides . The process that is followed is as follows:

  • Bauxite mining and handling
  • Settling or separation of solids
  • Solution creation
  • Cooling
  • NaOH recovery
  • Precipitation of Al (OH) 3
  • Calcination
  • Production of Al 2 O 3

What is it for

One of the main uses of aluminum hydroxide is in the medical field as it is one of the best antacids that alleviates heartburn, indigestion and stomach upset problems. It is very useful in patients suffering from peptic ulcers , esophagitis , hiatal hernia and other stomach problems because it produces an effect that neutralizes the acids that are produced in the stomach.

It is also used as a phosphate chelator in order to control hyperphosphatemia (very high levels of phosphate in the blood) in both humans and animals. Precipitated , it is included as an adjuvant in vaccines because it manages to correctly absorb the proteins, preventing them from precipitating or adhering to the walls of the vial while it is stored.

It can also be used as an extinguishing agent as it has the ability to absorb large amounts of heat and at the same time, it releases water vapor. Its fire resistance make it effective as a type of smoke suppressant mainly on polyester, ethylene , acrylics, epoxy resin, rubber and PVC.

How is it taken

The dose to be able to take aluminum hydroxide as a medicine must be established by a doctor depending on the age, weight and health condition. It is important to shake the product well in case it is in suspension form and all the indications of the medicine must be followed to the letter. So overall , not indicated in children who are under five and adults , the usual dose is one to two tablets three times a day, especially 20 minutes or hourafter food has been eaten . An extra dose may also be indicated in the event of a pain crisis . If you are taking the chewable tablets , chew them well before swallowing, and then drink a full glass of water.

Aluminum hydroxide benefits

The benefits that can be obtained by means of aluminum hydroxide are mentioned below:

  • It is an excellent product that works by regulating stomach acids that cause pain, discomfort and indigestion.
  • Although they regulate the production of hydrochloric acid in the stomach, they do not reduce or affect it.
  • In some cases, it can also be used as a laxative .

Importance in pregnancy

In the pregnancy stage, aluminum hydroxide can be of great importance to treat those women who have serious problems with heartburn and gastroesophageal reflux when the diet and the change in the lifestyle of the pregnant woman do not solve the problem. It is noteworthy that despite being an important drug, not recommended its excessive use prolonged .


Among the main risks that can be caused by ingesting aluminum hydroxide are the following:

  • It can be reached present toxicity of aluminum in patients suffering from renal failure.
  • They may generate low levels of phosphate in the blood (hypophosphatemia).
  • Patients with heart failure , cirrhosis , edema or kidney failure should take special care with the use of aluminum hydroxide.
  • Older adults may be predisposed to having a fecal impaction with the use of this drug.
  • It can cause irritation in the eyes if it comes into contact with them.

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