Magnesium hydroxide

Magnesium hydroxide (CAS 1309-42-8), also recognized in food and feed applications as E528, is an inorganic base and flame retardant used across industrial, food, and environmental sectors. Milk of magnesia is the widely recognized pharmaceutical and consumer form, while magnesium hydrate is a term commonly encountered in water treatment and industrial procurement.

Its primary commercial roles are pH regulation, halogen-free flame retardancy, and acid neutralization. In plastics and polymer compounding, it functions as a smoke suppressant. This is particularly useful in wire and cable jacketing, where regulatory pressure favors non-halogenated systems. Water treatment plants use it to neutralize acidic wastewater.

It helps stabilize pH without the overdose risk associated with stronger alkalis. In food manufacturing, it acts as an acidity regulator and firming agent in processed products. Pharmaceutical formulators incorporate it as an active antacid ingredient and excipient in solid dosage forms. It is supplied as a dry white powder, aqueous slurry, or granules.

Standard grades include USP, FCC, Ph. Eur., and technical grade, with flame retardant grades specified by particle size distribution and surface treatment. Slurry concentrations for water treatment are typically supplied at around 55–63% solids. These specifications ensure compatibility across diverse polymer and chemical systems.