Magnesium sulfate monohydrate
[CAS# 14168-73-1]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Metal sulfides and sulfates
• Name: Magnesium sulfate monohydrate
• Molecular Formula: MgSO₄.H₂O
• Molecular Weight: 138.38
• CAS Registry Number: 14168-73-1
• EC Number: 604-246-5
• SMILES: O.[O-]S(=O)(=O)[O-].[Mg+2]

Properties

• Density: 2.57 g/mL (Expl.)
• Melting point: 150 °C (Decomposes) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H371
• Safety Statements: P501-P260-P270-P264-P308+P311-P405

Discovery and Applications

Magnesium sulfate monohydrate is an inorganic compound with the chemical formula MgSO₄·H₂O. It is one of several hydrated forms of magnesium sulfate, which also include the heptahydrate (commonly known as Epsom salt) and other intermediate hydrates. The monohydrate form is a white crystalline solid that is soluble in water and exhibits a moderately high melting point.

Magnesium sulfate has been known since ancient times, primarily in its heptahydrate form, which occurs naturally in mineral deposits such as kieserite and epsomite. The monohydrate form is typically produced by the controlled dehydration of the heptahydrate or through crystallization from aqueous solutions of magnesium sulfate under specific thermal conditions. Industrially, magnesium sulfate monohydrate is produced as part of the broader production and refining processes for magnesium salts, often from seawater or brines rich in magnesium.

One of the most common applications of magnesium sulfate monohydrate is in agriculture and horticulture as a source of magnesium and sulfur, two essential plant nutrients. Magnesium is a central component of the chlorophyll molecule and is crucial for photosynthesis, while sulfur is involved in protein synthesis and enzyme function. Magnesium sulfate monohydrate is used to correct magnesium deficiency in crops such as potatoes, tomatoes, and citrus fruits. It is often applied as a soil amendment or dissolved in irrigation water or foliar sprays.

In the pharmaceutical and health industries, magnesium sulfate is better known in its heptahydrate form, but the monohydrate form may be used in certain formulations that require lower hydration levels for improved stability or controlled release. Magnesium sulfate acts as a saline laxative, osmotic diuretic, and anticonvulsant. It has been used in medical settings for the management of preeclampsia, eclampsia, and magnesium deficiency.

Magnesium sulfate monohydrate also finds use in industrial applications such as in the production of textiles, paper, and leather. It serves as a coagulant in rubber processing and as a catalyst support or reactant in certain chemical synthesis pathways. In the construction industry, it is used in special cements and fireproofing materials due to its ability to contribute to hardness and thermal resistance.

The compound is also employed in laboratory settings, where it may serve as a drying agent for organic solvents under specific conditions or as a source of magnesium ions in chemical reactions. While not as common as the anhydrous form for drying, the monohydrate is useful in applications where a moderate water content is desirable or required.

Magnesium sulfate monohydrate is generally recognized as safe when handled and used appropriately. It is not considered highly hazardous, but like other magnesium salts, excessive ingestion can lead to adverse effects such as gastrointestinal upset or, in extreme cases, disturbances in electrolyte balance. Environmental impacts are minimal, as the compound is water-soluble and breaks down into naturally occurring ions in soil and water.

In summary, magnesium sulfate monohydrate is a well-established chemical compound used widely in agriculture, industry, and certain pharmaceutical contexts. Its efficacy as a nutrient source, its solubility, and its compatibility with a range of materials and processes ensure its continued relevance across multiple fields of application.

References

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2022. Formation process and thermodynamic mechanism of the crust in magnesite mining areas. Arabian Journal of Geosciences, 15(8).
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2021. Long-Term Efficiency of Silica Fume in Terms of Sulfate Resistance of Concrete Immersed in Sulfate Solutions and Seawater. Iranian Journal of Science and Technology, Transactions of Civil Engineering, 45(4).
DOI: 10.1007/s40996-021-00750-4