Ferrous sulfate hydrate
[CAS# 13463-43-9]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal sulfides and sulfates
• Name: Ferrous sulfate hydrate
• Synonyms: Iron vitriol
• Molecular Formula: FeSO₄.H₂O
• Molecular Weight: 169.92
• CAS Registry Number: 13463-43-9
• EC Number: 603-840-1
• SMILES: O.[O-]S(=O)(=O)[O-].[Fe+2]

Properties

• Solubility: soluble (water)
• Density: 1.898 g/mL

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319
• Safety Statements: P264-P264+P265-P270-P280-P301+P317-P302+P352-P305+P351+P338-P321-P330-P332+P317-P337+P317-P362+P364-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Acute toxicity	Acute Tox.	4	H302
Acute hazardous to the aquatic environment	Aquatic Acute	1	H400
Chronic hazardous to the aquatic environment	Aquatic Chronic	1	H410
Skin sensitization	Skin Sens.	1	H317
Specific target organ toxicity - single exposure	STOT SE	3	H335

• Transport Information: UN 3077

Discovery and Applications

Ferrous sulfate hydrate, also known as iron(II) sulfate hydrate, is a chemical compound with the formula FeSO4·xH2O, where "x" represents the number of water molecules associated with the iron sulfate. It is a commonly encountered iron salt that has various industrial, agricultural, and medicinal applications. The compound appears as blue-green or pale green crystals, depending on its hydration state, and it is soluble in water.

The discovery of ferrous sulfate hydrate dates back to ancient times when iron salts were used for various purposes, including as a pigment and a mordant in the textile industry. The industrial-scale production of ferrous sulfate hydrate became more prominent during the 19th century as methods for synthesizing and purifying iron salts advanced. The compound is typically produced by reacting iron with sulfuric acid, resulting in the formation of iron(II) sulfate, which can then be hydrated under controlled conditions to form the hydrate.

In industrial applications, ferrous sulfate hydrate is used as a precursor in the production of other iron compounds. One of the most important uses of ferrous sulfate hydrate is in the production of ferric sulfate, a compound used in water treatment and as a coagulant in the purification of drinking water. The hydrated form of ferrous sulfate is also used as a reducing agent in various chemical processes, including in the synthesis of chemicals like hydrogen peroxide and in reducing metal ores.

In agriculture, ferrous sulfate hydrate is employed as a fertilizer and soil amendment to correct iron deficiencies in plants. Iron is an essential micronutrient for plant growth, and a deficiency can lead to chlorosis, a condition where plants exhibit yellowing of their leaves due to insufficient chlorophyll production. By adding ferrous sulfate hydrate to the soil, iron is made available to plants, promoting healthier growth and improving crop yields. It is especially useful for treating plants grown in alkaline soils, where iron availability is often limited.

Ferrous sulfate hydrate is also widely used in the pharmaceutical industry, particularly as an iron supplement for the treatment of iron-deficiency anemia. This condition occurs when there is a lack of iron in the body, leading to reduced production of hemoglobin and subsequent fatigue, weakness, and other health issues. Oral iron supplements containing ferrous sulfate hydrate are commonly prescribed to replenish iron levels and improve red blood cell production. The compound is easily absorbed by the body, making it an effective option for individuals with iron deficiency.

Additionally, ferrous sulfate hydrate finds application in the dyeing and textile industries, where it acts as a mordant. A mordant is a substance used to fix dyes to fabrics, particularly in natural dyeing processes. The compound helps to bind the dye molecules to the fibers, enhancing the color and durability of the fabric. It is also used in the preparation of ink, particularly iron gall ink, a type of ink historically used in writing and art.

The compound’s role in wastewater treatment is another significant application. In water treatment plants, ferrous sulfate hydrate is used to remove phosphorus and other impurities from wastewater. By adding the compound to the water, phosphorus is precipitated out of the solution, helping to reduce nutrient pollution and improve water quality. This application is particularly important in regions where excess phosphorus in water sources can lead to harmful algal blooms and other environmental issues.

In summary, ferrous sulfate hydrate is a versatile and valuable chemical compound with a wide range of applications. From its use as a soil amendment to its role in water treatment, iron supplements, and industrial processes, the compound plays a crucial part in numerous sectors. Its discovery and continued use reflect the ongoing importance of iron compounds in both industrial and everyday applications.

References

1979. Thermal analysis of ferrous sulphate heptahydrate in air. Journal of Thermal Analysis and Calorimetry, 16(1).
DOI: 10.1007/bf01903654

2023. Comparison of two pharmaceutical products containing ferrous sulfate using Mössbauer spectroscopy. Hyperfine Interactions, 244(1).
DOI: 10.1007/s10751-023-01835-4

2024. Properties of Powders Synthesized from Aqueous Solutions of Sodium Silicate and Iron Sulfate. Glass and Ceramics, 81(5-6).
DOI: 10.1007/s10717-024-00684-z