Magnesium hydroxide

Magnesium hydroxide (CAS 1309-42-8), also recognized in food and feed applications as E528, is an inorganic base and flame retardant.

Where is Magnesium hydroxide used?

• Plastics and polymer compounding: smoke suppressant, particularly in wire and cable jacketing where regulatory pressure favors non-halogenated systems
• Water treatment: neutralizes acidic wastewater and stabilizes pH without the overdose risk of stronger alkalis
• Food manufacturing: acidity regulator and firming agent
• Pharmaceutical formulators incorporate it as an active antacid ingredient and excipient in solid dosage forms.
• Precipitates heavy metals such as lead, cadmium and copper from industrial effluents.
• Suitable for polypropylene compounds and engineering thermoplastics.
• Can be mixed with aluminum hydroxides to achieve better flame retardancy in a variety of polymer systems.

Good to know: Milk of magnesia is the widely recognized pharmaceutical and consumer form; magnesium hydrate is a term commonly encountered in water treatment and industrial procurement.

Formulation notes

• Preferred for polymer compounds processed at temperatures near or above the decomposition point of aluminum hydroxide (about 220°C).
• Flame retardants are thermally stable at temperatures up to 110°C higher than ATH.
• Due to its alkaline nature, it should be avoided in contact with acidic components during formulation and application.

Typical specification

• A Ph.Eur.12.Ed. grade is available as powder with 41.7% theoretical magnesium, white, neutral, pH of 1% solution approximately 10-10.5, and API documentation (ASMF/DMF) and CEP available.
• Heat of decomposition is 328 cal/g.
• Theoretical loss on ignition is 31.0%.
• Assay is at least 94% determined by complexometry.

Regulatory status

• Production complies with Ph. Eur., USP/NF and E number standards.
• Has ATC codes G04BX01 and A02AA04.
• REACH compliant and regulatory support is provided.
• When requesting API, specify the required pharmacopoeia standard such as EP (Ph. Eur.), USP, JP, or BP, as well as the required grade (base, salt, micronized, specific purity, etc.).

Storage, packaging and handling

• Should be protected from moisture.

Frequently asked questions about Magnesium hydroxide

What function does magnesium hydroxide serve in polymer applications?

It acts as an acid scavenger for neutralizing acids, improving stability and durability.

Can magnesium hydroxide be supplied to custom specifications?

Custom specifications are available in different particle sizes and qualities.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.