Aluminum Sulfate

Aluminum sulfate may sound foreign to some people. Without realizing it, this chemical compound with the formula Al₂(SO₄)₃ has an important role in everyday life.

Before discussing the role of aluminum sulfate in more depth, you first need to understand what the properties of this compound are.

What is Aluminum Sulfate?

Aluminum sulfate is a compound of two elements – aluminum and sulfuric acid. Usually found in powder form, but can also be in solution form. However, the solid form is more commonly used because it is easier to store and transport.

This compound is used for various purposes, for example water purification, fabric dyeing, pH level adjustment, paper making, medical purposes, and others.

Properties of Aluminum Sulfate

Aluminum sulfate or alum is a chemical compound that is usually used as a coagulation agent for purifying drinking water, paper making and wastewater treatment plants. In its anhydrous form, alum has the appearance of white crystals. However, it is colorless in liquid form. Both forms are non-flammable and non-toxic.

The following is a table of the properties of aluminum sulfate

Chemical formula



Available in solid form: granules or powder


2,67 g/cm³

Molar mass

342,15 g/mol

Boiling point


Melting point

770 °C


Very easily soluble in water


Easily absorbs water from the air





What are the Functions of Aluminum Sulfate?

Aluminum sulfate has a variety of important uses in various areas of daily life. Here are some of its main uses.

1. Water Treatment

Raw water often contains suspended particles such as mud, clay, algae, bacteria and other organic materials. These particles cause the water to be cloudy, smelly, and contain unwanted substances.

Therefore, this material plays an important role in the water treatment process. When added to water, alum causes microscopic impurities to clump together into increasingly larger particles. This process is known as coagulation.

The clots that have formed will settle to the bottom of the container so they can be filtered. This makes the water safer to drink.

2. Medical Use

Aluminum sulfate has several practical uses in the medical field. It is mainly used as a coagulation agent in treating minor wounds and abrasions as well as a deodorant (due to its antibacterial properties).

This compound also adsorbs and precipitates protein antigens in solution. The resulting precipitate increases the immunogenicity of the vaccine by facilitating the slow release of antigen from the vaccine depot formed at the site of inoculation.

Alum is found in materials used in the pharmaceutical industry. For example, it is used in making ear drops.

3. Fabric Dyeing

Another use of alum is to dye fabric. When dissolved in a large amount of water that has a neutral or slightly alkaline pH, the compound produces a sticky substance, aluminum hydroxide.

This liquid helps the dye stick to the fabric fibers by making the dye insoluble in water. The next role of alum is as a “fixer” dye, which means it blends with the molecular structure of the dye and the fabric so that the dye doesn’t run out when the fabric gets wet.

4. Paper Making

Aluminum sulfate plays a role in helping paper be more resistant to ink by reducing the absorbency of the paper. Paper that is not treated with aluminum sulfate easily absorbs ink, causing the ink to spread and the writing to become unclear.

Additionally, alum helps increase paper strength by reducing the hydrophilic properties of cellulose fibers. This way, the paper becomes more water and tear resistant.

Need Aluminum Sulfate for Your Business?

Lautan Air Indonesia is a company that operates in the field of water treatment and provides various quality chemical products, including aluminum sulfate.

The aluminum sulfate that we provide has various benefits for various industries. For further information, you can contact us here.


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