What Are Some Popular Aluminum Sulfate Uses?

There are many aluminum sulfate uses, both in the industrial as well as in the public sector. It has different properties that make it useful in manufacturing cloth and paper, tanning leather, and also for water treatment and fire suppression.

Water Treatment Plants

Aluminum sulfate is widely used in water and sewage treatment plants. Adding the chemical to contaminated water causes pollutants to sink to the bottom where they can be easily removed. Since the chemical binds to the pollutants it is removed with them during filtering, leaving clean water behind. The process is called flocculation and it is used to treat water all over the world. Private consumers also use aluminum sulfate in ponds to eliminate phosphates and algae.

Paper Manufacturing

Perhaps the second largest aluminum sulfate use is in the making of paper. In the early 19th century, the chemical was used first to remove impurities from the water used to create the pulp and then added to the pulp to help retain the clay fillers, pigments, resin and fibers used to make the paper. Lastly it was used to speed up the bleaching action of chlorine, but in this use it caused damage to the cellulose fibers and weakened the finished paper. It is commonly used in paper pulp today.

Textile Industry Uses

In the textile industry, aluminum sulfate is used as a mordant or agent that fixes the dye in the fabric. While synthetic dyes usually don't require a mordant, natural vegetable and mineral dyes often do not hold their color in the fabric without one. Artists and crafters who work with natural fibers and dyes also use the chemical to fix the dyes in their creations. Iron free aluminum sulfate helps maintain the color of the dye and is the best choice for crafters.

Tanning Leather

Leather is used in popular fashions, furniture and in some safety gloves and it must be tanned before it can be worked. Many tanners use a mixture of aluminum sulfate, sodium carbonate, sodium chloride and flour which is made into a paste and applied to the dried skins. The paste is allowed to sit on the skin for at least 24 hours before it is scraped off and reapplied. This is repeated several times. The sulfate acts as a preservative and prevents the skin from decaying.

Firefighting Foams

Although most fires can be extinguished with water, chemical, electrical and oil fires are more difficult to extinguish. Water may even react with chemicals and cause a fire to burn hotter. In the early 1800s, scientists began experimenting with foams to suffocate fires that could not be extinguished with water. The most successful firefighting foam is a mixture of sodium bicarbonate and aluminum sulfate and is effective in putting out fires where water cannot be used.

While most aluminum sulfate uses are commercial, it has applications in home arts and crafts and agricultural water treatment. Chicken farmers use it in coops to reduce nutrient run off into water ways. Even though most consumers have never heard of the chemical, chances are they use products made with it every day.