Sodium perborate monohydrate
[CAS# 10332-33-9]

Identification

• Classification: Inorganic chemical industry >> Inorganic salt >> Boride, borate and perborate
• Name: Sodium perborate monohydrate
• Synonyms: Perboric acid sodium salt monohydrate
• Molecular Formula: NaBO₃.H₂O
• Molecular Weight: 99.81
• CAS Registry Number: 10332-33-9
• EC Number: 600-419-4
• SMILES: B(=O)O[O-].O.[Na+]

Safety Data

• Hazard Symbols: GHS03;GHS05;GHS06;GHS07;GHS08 Danger
• Risk Statements: H272-H302+H332-H302-H318-H331-H332-H335-H360
• Safety Statements: P203-P210-P220-P261-P264-P264+P265-P270-P271-P280-P301+P317-P304+P340-P305+P354+P338-P316-P317-P318-P319-P321-P330-P370+P378-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H302
Serious eye damage	Eye Dam.	1	H318
Oxidising solids	Ox. Sol.	3	H272
Reproductive toxicity	Repr.	1B	H360
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	3	H331

• Transport Information: UN 3377

Discovery and Applications

Sodium perborate monohydrate is an inorganic compound with the formula NaBO₃·H₂O. It is a white, crystalline solid and serves as a stable source of active oxygen. It is widely used as a bleaching agent in laundry detergents and various cleaning products. The compound contains a perborate anion, which includes a peroxy linkage (–O–O–) within a borate structure, and one molecule of water of hydration per formula unit.

The history of sodium perborate dates back to the early 20th century, when it was developed as an alternative to unstable hydrogen peroxide for use in household and industrial bleaching. The monohydrate form is one of the most commonly encountered, along with the tetrahydrate form (NaBO₃·4H₂O). The monohydrate has a higher active oxygen content by weight compared to the tetrahydrate, making it more efficient and compact for many applications.

Sodium perborate is typically produced by reacting sodium metaborate with hydrogen peroxide, followed by crystallization. The monohydrate is formed when the reaction conditions favor low hydration levels, usually under reduced humidity or elevated temperatures. The compound remains stable under dry conditions and decomposes upon exposure to moisture or acids, releasing hydrogen peroxide.

Its most prominent application is as a bleaching agent in powdered laundry detergents. When dissolved in water, sodium perborate releases hydrogen peroxide, which acts as an oxidizing agent that breaks down stains, particularly those from organic compounds such as food and blood. This bleaching occurs effectively at moderate temperatures, typically above 40 °C. To enhance its performance at lower temperatures, it is often used in conjunction with bleach activators such as tetraacetylethylenediamine (TAED), which react with hydrogen peroxide to produce peracetic acid, a more active oxidizer at lower temperatures.

In addition to laundry detergents, sodium perborate monohydrate has been used in other cleaning products, including denture cleaners, toilet bowl cleaners, and surface disinfectants. Its antimicrobial properties arise from its oxidative mechanism, which damages microbial membranes and proteins, leading to cell death.

In cosmetics and personal care, sodium perborate has been included in formulations for teeth whitening and mouth rinses. However, its use in oral products has declined in some regions due to regulatory changes and concerns over safety with prolonged exposure.

From an environmental perspective, sodium perborate breaks down into non-toxic byproducts such as borate and oxygen, but the accumulation of boron in ecosystems has raised concerns. Therefore, its use has been restricted or phased out in certain countries, particularly within the European Union, in favor of more environmentally benign bleaching agents like sodium percarbonate.

Analytical techniques used to characterize sodium perborate include thermogravimetric analysis (TGA) to measure its water content and decomposition behavior, and iodometric titration to quantify its active oxygen content. Infrared (IR) spectroscopy can detect the peroxy and borate functional groups, while X-ray diffraction (XRD) is employed to determine its crystalline structure.

Storage of sodium perborate monohydrate requires dry conditions and protection from acids and reducing agents. It is generally considered safe to handle when used as directed, but it can be irritating to the eyes and respiratory tract. Proper labeling and hazard classification are implemented in industrial and consumer products to ensure safe use.

In summary, sodium perborate monohydrate is a widely used oxidizing and bleaching agent with a long-standing role in cleaning and hygiene applications. Its ability to release hydrogen peroxide in a stable and controlled manner makes it suitable for a variety of formulations. Despite growing environmental considerations, it remains an important chemical in many household and industrial processes.

References

2018. The Chemical and Products Database, a resource for exposure-relevant data on chemicals in consumer products. Scientific Data, 5.
DOI: 10.1038/sdata.2018.125

Boron, Metallo-Boron Compounds and Boranes. New York, John Wiley & Sons, Inc., 1964, -(693).
URL: Not available