What is Magnesium Hydroxide CAS 1309-42-8?

Magnesium hydroxide is a white inorganic powder with low water solubility. It is used as a flame retardant, acid neutralizer, pH buffer and source of magnesium in industrial, environmental and pharmaceutical applications.

How does magnesium hydroxide work as a flame retardant?

It decomposes endothermically at high temperature, releasing water vapor and forming magnesium oxide. This removes heat from the polymer and dilutes flammable gases, while the oxide residue contributes to char formation and smoke suppression.

At what temperature does decomposition begin?

Magnesium hydroxide normally begins significant decomposition around 300-330 degrees Celsius. This thermal stability is higher than many hydrated fillers, making it suitable for polymers processed at elevated temperatures.

Why is it useful in wastewater treatment and acid neutralization?

Its low solubility provides controlled release of hydroxyl ions, buffering pH to a moderate alkaline level and reducing the risk of over-alkalization compared with strong bases. It also produces less sludge in many neutralization applications.

What are the main applications?

Typical uses include halogen-free flame-retardant compounds, wire and cable, plastics and rubber, wastewater neutralization, flue-gas desulfurization, chemical intermediates, pharmaceuticals and mineral-based products.

Which grade and packaging are available?

The listing is industrial/flame-retardant grade with 95-99% magnesium hydroxide, customizable on request. It is supplied in 25 kg woven bags with an inner PE liner or 500-1000 kg jumbo bags on pallets.

What specifications should be checked before ordering?

Confirm magnesium hydroxide content, particle size, surface area, whiteness, moisture, loss on ignition, heavy metals and any surface treatment. Request the batch analysis, technical data and safety information before purchase.

How should magnesium hydroxide be stored and handled?

Store in tightly closed bags in a cool, dry, ventilated area away from acids, moisture and incompatible materials. Use dust-control measures and suitable respiratory protection, and follow the safety information for handling and disposal.

Magnesium Hydroxide (CAS 1309-42-8)

Magnesium Hydroxide (Mg(OH)2) is an inorganic compound supplied under CAS 1309-42-8 for halogen-free flame retardant, smoke suppression, and water treatment applications. We can discuss industrial and flame-retardant grades, customized particle size, coated or uncoated options, and supporting documents such as COA, TDS, and SDS/MSDS according to buyer requirements.

CAS: 1309-42-8
Synonyms: Magnesium dihydroxide, Brucite, Milk of magnesia (suspension), Magnesium hydroxide powder, MDH flame retardant
Einecs: 215-170-3
Molecular Formula: Mg(OH)2
Grade: Industrial / Flame-retardant grade (95–99% Mg(OH)₂, customized on request)
Package: 25 kg woven bag with inner PE liner / 500–1000 kg jumbo bag on pallet, customizable

Request a quote

Share:

Product Description

1 Product Overview

2 Physicochemical Properties

3 Applications

4 Storage Conditions

5 Safety Precautions

Product Overview

Magnesium hydroxide is an inorganic alkaline powder widely used as an environmentally friendly flame retardant, acid scavenger and smoke suppressant in plastics, rubber, cable compounds and industrial wastewater treatment. It offers high decomposition temperature, good thermal stability and low smoke, making it a popular halogen-free alternative to traditional flame retardant systems.

📧 Email: info@industrochem.com – Send us your specifications (grade, particle size, packaging) to get a tailored factory quotation.

Physicochemical Properties

Item	Typical Value / Description
Chemical Name	Magnesium hydroxide
CAS No.	1309-42-8
EINECS No.	215-170-3
Molecular Formula	Mg(OH)₂
Appearance	White to off-white fine powder
Odor	Odorless
Assay (Mg(OH)₂)	95.0–99.0% min (depending on grade)
Magnesium Oxide (as MgO)	Approx. 63–65% (by ignition)
Loss on Ignition	30–34%
Bulk Density	0.30–0.60 g/cm³ (tapped, grade dependent)
Particle Size (D50)	1–10 μm typical (can be customized for different applications)
Oil Absorption	20–40 g / 100 g
pH (10% slurry, 25 °C)	9.5–11.0
Specific Surface Area (BET)	5–20 m²/g (typical range)
Refractive Index	~1.57
Decomposition Temperature	Approx. 330–350 °C (releases water, absorbs heat)
Solubility in Water	Practically insoluble; ~0.009 g/L at 20 °C
Hardness	~2.5 (Mohs)
Heavy Metals	In line with common industrial flame-retardant standards
Halogen Content	Halogen-free

(The above values are typical data from industrial production and can be adjusted according to your required grade and particle size specification.)

Applications

Halogen-Free Flame Retardant & Smoke Suppressant
- Used in PVC cable compounds, PE/PP, EVA, rubber, thermosetting resins and engineering plastics.
- Decomposes at high temperature to release water and absorb heat, diluting combustible gases and reducing smoke.
Industrial Wastewater & Flue Gas Treatment
- Acts as an alkaline neutralizing agent and heavy-metal precipitant in acidic wastewater.
- Used in desulfurization and denitrification systems as a magnesium-based alkaline source.
Chemical Intermediate & Catalyst Carrier
- Raw material for magnesium salts (e.g. magnesium oxide, magnesium sulfate).
- Carrier or additive in catalysts and ceramic formulations.
Paper, Coatings & Filler Applications
- Functional filler in paper, coatings and inks to improve whiteness, opacity and flame resistance.
- Used in certain rubber and elastomer formulations for improved mechanical properties and flame behavior.
Other Industrial Uses
- Acid scavenger in polymer processing.
- Additive for building materials, mineral composites and other environmental products.

Storage Conditions

Store in a cool, dry and well-ventilated warehouse.
Keep the bags tightly closed to avoid moisture absorption and contamination.
Avoid direct sunlight and keep away from strong acids, ammonium salts and incompatible materials.
Recommended storage temperature: 5–35 °C.
Under proper storage conditions, typical shelf life is 24 months from production date; re-test before use if over the recommended period.

Safety Precautions

Magnesium hydroxide is generally considered low-toxicity, but industrial handling rules should still be followed.
Avoid dust generation; use local exhaust ventilation when charging or transferring the powder.
Wear appropriate PPE: dust mask or respirator, safety goggles and protective gloves.
In case of eye contact: rinse immediately with plenty of clean water for at least 15 minutes and seek medical advice if irritation persists.
In case of skin contact: wash with water and soap; remove contaminated clothing.
If inhaled: move the person to fresh air; get medical attention if respiratory irritation occurs.
Spill handling: sweep or vacuum up the material carefully to avoid dust; collect into suitable containers for reuse or disposal according to local regulations.

FAQ - Technical & Supply Chain

Q:
What is Magnesium Hydroxide CAS 1309-42-8?

A: Magnesium hydroxide is a white inorganic powder with low water solubility. It is used as a flame retardant, acid neutralizer, pH buffer and source of magnesium in industrial, environmental and pharmaceutical applications.
Q:
How does magnesium hydroxide work as a flame retardant?

A: It decomposes endothermically at high temperature, releasing water vapor and forming magnesium oxide. This removes heat from the polymer and dilutes flammable gases, while the oxide residue contributes to char formation and smoke suppression.
Q:
At what temperature does decomposition begin?

A: Magnesium hydroxide normally begins significant decomposition around 300-330 degrees Celsius. This thermal stability is higher than many hydrated fillers, making it suitable for polymers processed at elevated temperatures.
Q:
Why is it useful in wastewater treatment and acid neutralization?

A: Its low solubility provides controlled release of hydroxyl ions, buffering pH to a moderate alkaline level and reducing the risk of over-alkalization compared with strong bases. It also produces less sludge in many neutralization applications.
Q:
What are the main applications?

A: Typical uses include halogen-free flame-retardant compounds, wire and cable, plastics and rubber, wastewater neutralization, flue-gas desulfurization, chemical intermediates, pharmaceuticals and mineral-based products.
Q:
Which grade and packaging are available?

A: The listing is industrial/flame-retardant grade with 95-99% magnesium hydroxide, customizable on request. It is supplied in 25 kg woven bags with an inner PE liner or 500-1000 kg jumbo bags on pallets.
Q:
What specifications should be checked before ordering?

A: Confirm magnesium hydroxide content, particle size, surface area, whiteness, moisture, loss on ignition, heavy metals and any surface treatment. Request the batch analysis, technical data and safety information before purchase.
Q:
How should magnesium hydroxide be stored and handled?

A: Store in tightly closed bags in a cool, dry, ventilated area away from acids, moisture and incompatible materials. Use dust-control measures and suitable respiratory protection, and follow the safety information for handling and disposal.

Ordering & Documentation

Key information for document requests, quotations, and supply planning.

Documents

COA, TDS, SDS/MSDS and packing details are available on request.

Quotation

Send the CAS number, grade, quantity, packing preference and destination.

Sample & Supply

Support is available for samples, trial orders, bulk and repeat supply.

Storage & Shipping

Product-specific conditions are confirmed before order.

Current Language

Change Language