Synthetic magnesium silicates white, finely dispersed odorless powders. Synthetic magnesium silicates are formed in the precipitation (precipitation) reaction of water-soluble sodium silicate (water glass) and water-soluble magnesium salts such as magnesium chloride, magnesium nitrate or magnesium sulfate. The composition of the precipitate depends on the ratio of the components in the reaction mixture, the presence of other reagents, and the reaction conditions.

The molecular formula is usually written as MgO: XSiO2, where X represents the average molar ratio between SiO2 to MgO. The reaction product is wet and therefore the formula is sometimes written as: MgO: XSiO2 • H2O to indicate the presence of hydrated water.

Properties

Unlike natural crystalline magnesium silicates (talc, forsterite, olivine), synthetic magnesium silicates are amorphous. Synthetic magnesium silicates are insoluble in water and alcohol. The particles are usually porous. The BET surface area value can range from less than 100 m2 / g to several hundred m2 / g.

Applications

The large active surface allows the use of synthetic magnesium silicate in a variety of applications. When separating mixtures and purifying substances, synthetic magnesium silicates are used as adsorbents (in the separation of polyols, animal and vegetable oils, in chromatography. It is used in dry cleaning to remove sugars, resins, unpleasant odors. It is used as a filler for various materials: rubber, ceramics, paper, glass, refractory materials Used as an anti-caking agent Used as a catalyst or catalyst carrier Also used as a filter filler.

The US Food Additives Code, JECFA (Joint FAO-WHO Expert Committee on Food Additives), and a number of other monographs on food quality indicate that synthetic magnesium silicate, which can be used in food industry has the formula 2MgO: 5SiO2. Most often, food grade synthetic magnesium silicate is used for the adsorption of dyes from free fatty acids and other polar compounds from used frying oils. Various national and international regulations allow the use of synthetic magnesium silicate as an anti-caking agent for a wide variety of powdered products.

When used as a food additive, synthetic magnesium silicate is completely safe. In 1990, the safety of synthetic magnesium silicate was reviewed by the Scientific Committee on Food (SCF) along with silica and silicates of other alkali and alkaline earth metals. As a result, the SCF noted that „the available data, including a number of short-term studies in two species, indicate the biological inertness of these compounds." The SCF does not specify an acceptable daily intake (ADI) for silica and metal silicates.