توضیحات

After aluminum oxide, aluminum sulfate is recognized as the second most commonly used substance of the element aluminum. By lowering the pH level, this substance exhibits specific properties that can interact with the skin and corrosion of metal over time. Furthermore, due to the presence of aluminum ions with a triple positive charge, this compound has a high ability to absorb negative ions and can capture pollutant ingredient from water. Under alkaline conditions, the reaction of this compound with water leads to the formation of aluminum hydroxide with the molecular formula Al(OH)3 as a precipitate. Generally, this substance is found in various areas, including volcanoes and mining regions.

Methods of Aluminum Sulfate Production

In the processes for producing this substance, two main methods are commonly used. While there are other methods for producing this compound, the following two methods are among the most well-known and common:

Method 1: Using Sulfuric Acid

In this method, aluminum hydroxide is first added to a sulfuric acid solution. This combination results in a significant temperature increase and a chemical reaction. Then the solution got cooled. This process needed a reactor, acid-resistant high-temperature mixing equipment, and shallow cooling tanks.

2 Al(OH)3 + 3 H2SO4 → Al2(SO4)3 + 6 H2O

The material obtained from this process is typically white in color and in powdered form. The purity of aluminum in this substance is relatively high. Moreover, the purity of aluminum sulfate in it usually falls within the range of 85% to 95%.

With the use of these two primary methods, aluminum sulfate is produced and sent to subsequent stages for various applications.

Method 2: Using Bauxite Ore

Bauxite: The Primary Source of Aluminum

Obtaining aluminum sulfate from bauxite ore involves a complex process similar to the Bayer process, which will be briefly explained here:

1. Bauxite Dissolution: First, bauxite dissolved in a solution of caustic soda (sodium hydroxide). This process results in the formation of sodium aluminate.
2. Neutralization: Then, the formed sodium aluminate is transformed into aluminum trihydrate through a neutralization process by adding neutralizing agents. This compound collected as a sediment in separate tanks.
3. Adding Sulfuric Acid: Aluminum trihydrate is added to a solution of sulfuric acid and water.
4. Heating: Subsequently, the solution is gradually heated and boiled. This process is known as the “digestion process.” With the increase in temperature, aluminum sulfate is formed.

Using bauxite ore as the primary source for producing aluminum sulfate is of particular significance and has crucial role in aluminum production and its derivatives.

Method 3: Using Aluminum Shales

Aluminum shales, or aluminum sulfates, are typically composed of a mixture of iron pyrite, aluminum silicates, and various bituminous materials. Aluminum shales are often discarded or exposed to environmental factors such as air pollution.

This method utilizes aluminum shales as a secondary source for producing aluminum sulfate. This approach can contribute to waste management and optimal utilization of mineral resources.

Applications of Aluminum Sulfate

Aluminum sulfate is a chemical compound with a wide range of applications in various industries, particularly in the chemical, agricultural, and wastewater treatment sectors. Here are some important uses of this chemical compound:

Agricultural Applications of Aluminum Sulfate

Some interesting applications in this field include:

1. Soil pH Control: Due to the acidic nature of aluminum sulfate, it is added to highly alkaline soils to regulate pH levels. This application is commonly used in the planting of sugar beets, tomatoes, and other vegetables.
2. Changing Flower Colors: Gardeners use the pH-altering property of aluminum sulfate to change the color of some flowers, such as hydrangeas. These plants are highly sensitive to soil pH, and altering the soil environment can impact the flower colors.

It’s important to note that the use of this substance in agriculture should be done carefully and in appropriate amounts to prevent adverse effects on the soil or agricultural products.

Applications of Aluminum Sulfate in Water Treatment

Aluminum sulfate, as an effective coagulant and flocculant,  widely used in water treatment processes. Here are some important applications of aluminum sulfate in water treatment:

1. Removal of Impurities: When aluminum sulfate is added to water, it forms microscopic flocs. These impurity flocs gradually increase in size, allowing them to be removed through filtration or settling in tanks. This water treatment agent aids in the separation of impurities in water.
2. Reduce water turbidity: Aluminum sulfate can be used as a turbidity removal in water. This property is well-utilized in water treatment and in swimming pools to enhance water clarity and quality.
3. Hydrogen sulfide gas absorber: Research indicates that this substance is the primary source of hydrogen sulfide gas in wastewater systems. Aluminum sulfate is used as an adsorbent for this gas in water treatment processes.

For these reasons, aluminum sulfate is a important compound in maintaining the quality of drinking water and wastewater treatment. However, improper and careless use of this compound can lead to water and environmental pollution. Therefore, determining the appropriate and standard usage of chemical substances and adhering to water treatment regulations is necessary.