Industry Grade 99% Ferrous Sulfate Heptahydrate CAS 7782-63-0

What is ferrous sulfate heptahydrate? What are its uses?

What is Ferrous sulfate heptahydrate?

Ferrous sulfate heptahydrate (also known as green vitriol or iron sulfate heptahydrate) is a heptahydrate of divalent iron sulfate. It is a classic iron salt used in iron supplementation and chemical detection. Its chemical formula is usually written as:

FeSO4·7H2O (anhydrous FeSO4, CAS No.: 7782-63-0 (heptahydrate), 7720-78-7 (anhydrous), EINECS No.: 231-753-5, molecular weight approximately 278.01)

It is a blue-green crystal or granule at room temperature, odorless, with a melting point of approximately 64℃ (it loses its water of crystallization upon melting), and loses all seven molecules of water of crystallization at 90℃. Its relative density is approximately 1.898. It is readily soluble in water (approximately 48.6 g/100 g at 20℃), and its aqueous solution is pale green. Ferrous sulfate readily effloresces in dry air and is oxidized to a yellowish-brown ferric salt in humid air. Reagent-grade products must be refined from high-purity raw materials and subject to stricter purity and impurity control standards.

From a molecular structure perspective, ferrous sulfate consists of ferrous ions (Fe2+) and sulfate ions (SO42-) bonded together by ionic bonds, and contains seven molecules of water of crystallization. Ferrous iron possesses both reducing properties (easily oxidized to ferric iron) and is an essential iron source for the synthesis of hemoglobin in the human body—this dual property of "reducing property + iron source" makes it suitable as a reducing agent and iron standard reagent in analytical chemistry, as well as a raw material for oral iron supplementation, making it a classic iron salt in the field of detection.

Chemically, ferrous sulfate is easily oxidized in air to form a yellowish-brown ferric salt; it readily combines with tannic acid and tea polyphenols, affecting absorption, and excessive iron intake carries a risk of poisoning. The product must be stored in a sealed, moisture-proof, and light-protected environment to prevent oxidation and deterioration.

Non-food grade and non-industrial grade ferrous sulfate refers to products intended for testing applications, neither used in food processing nor in large-scale industrial applications. These primarily include reagent grade (compliant with national standards for chemical reagents). Compared to food grade and industrial grade, these products place greater emphasis on the following indicators:

Content (purity)

Reagent-grade reagents require high purity, and the content determines the accuracy of the analysis.

Heavy metal limits (lead, arsenic, etc.)

Reagent-grade reagents require low impurity background, which is a key indicator for ensuring analytical reliability.

Water-insoluble matter

The solution must be low in water-insoluble matter to ensure clarity and avoid interference from impurities in the analysis.

Free acid

The content of free sulfuric acid affects the acidity and stability of the product and must be controlled within the standard limits.

Clarity

The aqueous solution should be clear, free of turbidity and insoluble matter, reflecting the purity of the product and the level of process control.

What are the uses of Ferrous sulfate heptahydrate?

1. Water treatment applications

( 1 ) Ferrous sulfate is a commonly used coagulant, flocculant and phosphorus removal agent in the field of water treatment. It hydrolyzes to produce ferric hydroxide colloids that adsorb suspended solids and phosphorus. It is used in municipal sewage, industrial wastewater and tap water purification. It has the characteristics of low cost, excellent decolorization effect and large flocs with fast settling speed.

( 2 ) With the reducing properties of ferrous iron, hexavalent chromium in electroplating chromium wastewater can be reduced to trivalent chromium to achieve precipitation removal, which is the mainstream process for treating chromium wastewater. It can also treat mercury and arsenic wastewater.

2. Production of iron oxide pigments

It is a key raw material for the production of iron-based pigments such as iron oxide red, iron oxide yellow, and iron oxide black. Iron oxide red can be prepared by purifying ferrous sulfate, a by-product of titanium dioxide, and is widely used in paints, coatings, building materials, and ceramic coloring.

3. Production of iron salts such as polyferric sulfate

Ferrous sulfate is a raw material for the production of iron salt flocculants such as polyferric sulfate (PFS) and ferric sulfate, as well as iron-based chemicals. Ferrous sulfate heptahydrate, a byproduct of titanium dioxide production, can be refined into high-value-added polyferric sulfate.

4. Feed additives (iron supplements for animals)

Feed-grade ferrous sulfate is used as an iron nutrient additive in livestock and poultry feed to help prevent iron deficiency anemia and promote growth and development. It is a commonly used iron source in feed premixes.

5. Soil improvement and iron fertilizer (agriculture)

Ferrous sulfate is used as an iron fertilizer and soil conditioner to prevent iron deficiency chlorosis in plants and to improve alkaline soils. It is widely used in floriculture, horticulture, fruit tree, and lawn care . It is a commonly used iron fertilizer in floriculture (commonly known as "ferrous sulfate watering") to prevent chlorosis in plants and helps acid-loving plants (such as gardenias, jasmine, and azaleas) supplement their iron levels.

6. Nutritional fortification of infant formula and modified milk powder

According to GB 14880, ferrous sulfate is used for iron fortification in infant formula, modified milk powder, and modified cream powder to prevent iron deficiency anemia in infants and young children . It also provides iron supplementation for specific groups such as pregnant women, lactating mothers, and the elderly. Infant formula products must meet the corresponding food standards.

7. Breakfast cereals and fortified flour products

Ferrous sulfate is used as an iron source for iron-fortified breakfast cereals, fortified flour, and baked goods, helping to improve the iron nutrition status of staple food consumers. It is a commonly used iron source for fortifying cereal foods.

8. Health foods and dietary supplements (iron supplements)

Ferrous sulfate is used as a raw material for iron-supplemented health foods and dietary supplements, providing a convenient way for people at risk of iron-deficiency anemia to supplement iron. Products must be registered or filed and labeled with the appropriate population and dosage.

9. Analytical Chemistry Reagents (Reagent Grade)

Ferrous sulfate is a commonly used reagent for iron content determination and redox titration. It is used to prepare iron standard solutions, standardize oxidant concentrations, and determine various reducing substances. It is a classic iron salt reagent in analytical laboratories.

10. Scientific research and coordination chemistry research (research-level)

Ferrous sulfate is used in the study of iron chemistry, coordination chemistry and redox reaction mechanisms. It serves as a source of ferrous ions in the synthesis of complexes and the study of reaction kinetics, thus contributing to academic research and technological development.

It is important to note that non-food grade and non-industrial grade specifications do not equate to "risk-free": iron supplements must be taken according to the dosage, as excessive iron intake carries the risk of poisoning; reagent-grade products are for experimental use only and are strictly prohibited from consumption; the products are prone to oxidation and deterioration, and must be stored in sealed, moisture-proof, light-proof, and away from oxidants.

Summarize

Ferrous sulfate heptahydrate (FeSO4·7H2O, CAS No. 7782-63-0, anhydrous form 7720-78-7) is a blue-green crystalline solid known as "green vitriol." It is readily soluble in water and possesses both the reducing properties of ferrous iron and the characteristics of an iron source, making it a classic iron salt in the fields of iron supplementation and chemical detection. In daily life, we encounter it through iron supplementation, testing and analysis services, scientific research and university laboratories, teaching experiments, and the industrial supply chain. In non-food and non-industrial sectors, reagent-grade products that meet chemical reagent standards serve fields such as iron content analysis, coordination chemistry research, teaching experiments, and feed iron supplementation, making it an important ferrous salt connecting "iron chemistry" with "detection, scientific research, and animal husbandry."