Ammonium sulfate
[CAS# 7783-20-2]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal sulfides and sulfates
• Name: Ammonium sulfate
• Molecular Formula: (NH₄)₂.SO₄
• Molecular Weight: 132.14
• CAS Registry Number: 7783-20-2
• EC Number: 231-984-1
• SMILES: [NH4+].[NH4+].[O-]S(=O)(=O)[O-]

Properties

• Density: 1.76
• Melting point: 280 °C
• Water solubility: 77 g/100 mL (25 °C)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Specific target organ toxicity - single exposure	STOT SE	3	H336
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412
Skin corrosion	Skin Corr.	1B	H314
Serious eye damage	Eye Dam.	1	H318
Specific target organ toxicity - single exposure	STOT SE	2	H371
Acute toxicity	Acute Tox.	3	H331

Discovery and Applications

Ammonium sulfate, an inorganic salt with the formula (NH4)2SO4, was first synthesized in the early 19th century. By reacting ammonia with sulfuric acid, scientists produced a crystalline compound that was easy to handle and highly soluble in water. The production of ammonium sulfate became more industrialized in the late 19th and early 20th centuries, particularly with the advent of synthetic ammonia production through the Haber-Bosch process, which revolutionized fertilizer production and agriculture.

Ammonium sulfate is extensively used as a nitrogen fertilizer in agriculture. It provides two essential nutrients: nitrogen and sulfur. Nitrogen is a critical component of amino acids, proteins, and chlorophyll, essential for plant growth. Sulfur is important for enzyme function and protein synthesis. Ammonium sulfate is particularly beneficial for alkaline soils as it helps lower the pH balance while providing nutrients. Its high solubility ensures quick availability of nutrients to plants, promoting vigorous growth and high crop yields.

Besides its use as a fertilizer, ammonium sulfate serves as a soil amendment to improve soil structure and fertility. In acidic soils, it can enhance nutrient availability and soil health. It is also used to correct sulfur deficiencies in soils, which can be crucial for certain crops like canola and legumes that have high sulfur requirements.

Ammonium sulfate is used in various industrial processes. It serves as a flame retardant by lowering the combustion temperature of materials and reducing the emission of combustible gases. It is also used in the textile industry for dyeing and printing fabrics, where it helps fix dyes to fibers. In the food industry, it acts as an acidity regulator in bread and flour products.

Ammonium sulfate is utilized in water treatment plants as a coagulant aid. It helps in the removal of impurities by aiding in the coagulation and sedimentation processes, resulting in cleaner water. It is also used in the production of chloramines, which are disinfectants used to treat drinking water and wastewater.

In biochemistry and molecular biology, ammonium sulfate precipitation is a common technique for purifying proteins. By altering the solubility of proteins, it allows researchers to isolate and concentrate specific proteins from complex mixtures.

Ammonium sulfate is often used as an adjuvant in herbicides to enhance their effectiveness. It helps improve the uptake of herbicides by plants, particularly in hard water conditions where mineral ions can reduce herbicide efficacy. By binding to these ions, ammonium sulfate ensures that the active ingredients in herbicides are more readily absorbed by the target plants.

References

1991. Purification and characterization of p-coumaroyl-D-glucose hydroxylase of sweet potato (Ipomoea batatas) roots. Archives of Biochemistry and Biophysics, 284(1).
DOI: 10.1016/0003-9861(91)90277-p

1979. Tissue and regional distribution of cysteic acid decarboxylase. A new assay method. Neurochemical Research, 4(2).
DOI: 10.1007/bf00964144

1979. Sulfate aerosol generation and characterization for controlled human exposures. American Industrial Hygiene Association Journal, 40(7).
DOI: 10.1080/15298667991430064