Magnesium Hydroxide is a chemical compound, a natural material produced from magnesium chloride in seawater by precipitation or oxidation of the metal caused by the by-products of sonolysis by molecular cleavage of water

It appears as a non-toxic and non-corrosive white powder that is poorly soluble in water.

What it is used for and where

Food

An ingredient on the European food additives list as E528 acting as an alkaline drying agent, fungicide (1) and is generally recognised as a safe ingredient.

Cosmetics

Absorbent. Absorbs substances dispersed or dissolved in aqueous solutions, water/oil, oil/water.

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

Medical

Magnesium hydroxide is used in the treatment of magnesium deficiency in diabetics, as an antacid in stomach ache, heartburn and indigestion. It is also used as an occasional laxative (2). It is, however, a chemical compound that must be prescribed by a doctor.

Other uses

• in the plastics industry is used as a superior endothermic flame retardant and smoke suppressant
• adsorbent for dyes
• residual oil additive
• clarifier in sugar refining 
• coagulation removal of microplastics from wastewater

• Molecular Formula   H₂MgO₂
• Molecular Weight    58.320  
• CAS      1309-42-8 
• UNII    NBZ3QY004S
• EC Number   215-170-3

References_____________________________________________________________________

(1) European Food Safety Authority (EFSA), 2023. Outcome of the consultation with Member States and EFSA on the basic substance application for approval of magnesium hydroxide E 528 to be used in plant protection as a fungicide on grapevines, olives, banana, oat, rye, triticale, wheat, tomatoes, aubergine, sweet pepper, chili, Physalis sp. and pepino, potatoes, rosebush, ornamental plants, peach, apricot, cherry, plum, nectarine, mirabelle and rice crops (Vol. 20, No. 3, p. 7902E).

(2) Plan, D. and Additives, F., Magnesium hydroxide.