Trisodium phosphate
[CAS# 7601-54-9]

Identification

• Classification: API >> Special medicine >> Radioisotope
• Name: Trisodium phosphate
• Synonyms: Phosphoric acid trisodium salt; Sodium orthophosphate; Sodium phosphate
• Molecular Formula: Na₃PO₄
• Molecular Weight: 163.94
• CAS Registry Number: 7601-54-9
• EC Number: 231-509-8
• SMILES: [O-]P(=O)([O-])[O-].[Na+].[Na+].[Na+]

Properties

• Density: 1.62 g/mL (Expl.)
• Melting point: 75 °C (decomp.) (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P271-P280-P302+P352-P304+P340+P312-P305+P351+P338-P332+P313-P337+P313-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin corrosion	Skin Corr.	1B	H314
Serious eye damage	Eye Dam.	1	H318
Substances or mixtures corrosive to metals	Met. Corr.	1	H290
Acute toxicity	Acute Tox.	3	H331
Skin corrosion	Skin Corr.	1C	H314

• Transport Information: UN 9148; UN 3262

Discovery and Applications

Trisodium phosphate (TSP) is an inorganic compound with the chemical formula Na₃PO₄. Recognized for its powerful cleaning and degreasing properties, TSP is widely used across industrial, household, and food applications. It is part of the phosphate family, which has been studied extensively since the early 20th century for its versatile chemical properties. Trisodium phosphate is a white, granular or crystalline solid that dissolves readily in water to form a strongly alkaline solution. This alkaline nature enables TSP to break down grease, oil, and other contaminants, making it a highly effective cleaning agent.

One of the primary applications of TSP is in heavy-duty cleaning. It has been a favored compound in industrial and residential cleaning products due to its ability to remove stains, grease, and mildew from surfaces. TSP is especially popular for cleaning walls before painting because it efficiently removes dirt, grime, and previous coatings, providing a smooth, clean surface for paint adhesion. In household settings, TSP is used in solutions to clean tiles, grout, and other hard surfaces, though its use is regulated due to its high phosphate content, which can impact the environment when improperly disposed of in wastewater systems.

In the food industry, trisodium phosphate is utilized as an additive in various food products. The FDA has approved its use in certain quantities as an acidity regulator, emulsifier, and thickening agent. In processed meat, TSP is used to retain moisture, improve texture, and enhance shelf life. In cereals, cheeses, and baked goods, it aids in controlling acidity and helps to maintain product consistency and quality. Due to its versatility, TSP has been essential in enhancing food stability and appearance, ensuring that products meet the consumer’s expectations for taste and freshness.

Beyond cleaning and food applications, TSP plays a critical role in water treatment, particularly in boiler systems and cooling towers. Its ability to sequester calcium and magnesium ions prevents scale buildup, extending the life and efficiency of water systems. This function is vital in industrial settings, where mineral deposits can lead to corrosion, equipment damage, and reduced operational efficiency. TSP acts as a water-softening agent, removing hardness and thereby preserving system performance in municipal and industrial water treatment plants. It is also commonly used in the textile and paper industries to soften water, improving the quality of the final product.

The detergent industry, however, has largely moved away from TSP in recent years due to environmental concerns. Excess phosphates in wastewater can lead to eutrophication, a process that causes an overgrowth of algae in water bodies, which can deplete oxygen levels and harm aquatic ecosystems. Consequently, many countries have implemented regulations to limit phosphate usage in household detergents and cleaners. In response, the industry has shifted to phosphate-free formulations, although TSP remains available for specialized industrial cleaning applications where alternatives may be less effective.

TSP is also used in the construction industry as a degreaser for concrete and as a flux in welding. It helps to clean and prepare metal surfaces before soldering or welding, ensuring strong bonds by eliminating oils and oxides. Additionally, TSP can be used to treat rust on metals, making it a valuable compound in surface preparation for construction and maintenance work. In this capacity, TSP’s versatility and effectiveness have made it a key substance in construction, restoration, and repair work.

In summary, trisodium phosphate is a highly effective chemical used across a variety of industries due to its strong cleaning, emulsifying, and sequestering properties. Though its environmental impact has led to reduced use in some applications, TSP continues to be a valuable agent in heavy-duty cleaning, food processing, water treatment, and industrial processes, showcasing the compound's remarkable adaptability and usefulness.

References

2024. Rickets and Osteomalacia: Vitamin D-Sensitive and -Resistant States. Bone Metabolism, Parathyroid Glands, and Calciotropic Hormones, 2024.
DOI: 10.1007/978-3-030-24417-0_5

1979. Purification and characterization of mouse glucose 6-phosphate dehydrogenase. Molecular and Cellular Biochemistry, 24(3).
DOI: 10.1007/bf00314887