E520 Acidity regulator

It is sometimes used in the human food industry as a firming agent, where it takes on E number E520, and in animal feed as a bactericide. In the USA, the FDA lists it as "generally recognized as safe" with no limit on concentration.E520 may be used as a deodorant, an astringent, or as a styptic for superficial shaving wounds.

It is a common vaccine adjuvant and works "by facilitating the slow release of antigen from the vaccine depot formed at the site of inoculation."

E520 is used in water purification and as a mordant in dyeing and printing textiles. Water purification causes suspended impurities to coagulate into larger particles and then settle to the bottom of the container (or be filtered out) more easily. This process is called coagulation or flocculation. Research suggests that in Australia, E520 used this way in drinking water treatment is the primary source of hydrogen sulfide gas in sanitary sewer systems. An improper and excess application incident in 1988 polluted the water supply of Camelford in Cornwall.

When dissolved in a large amount of neutral or slightly alkaline water, E520 produces a gelatinous precipitate of E520. In dyeing and printing cloth, the gelatinous precipitate helps the dye adhere to the clothing fibers by rendering the pigment insoluble.

E520 is sometimes used to reduce garden soil pH, as it hydrolyzes to form the E520 precipitate and a dilute sulfuric acid solution. An example of what changing the pH level of soil can do to plants is visible when looking at Hydrangea macrophylla. The gardener can add E520 to the soil to reduce the pH, resulting in the flowers of the Hydrangea turning a different color (blue). The aluminum is what makes the flowers blue; at a higher pH, the aluminum is not available to the plant.

In the construction industry, it is used as a waterproofing agent and accelerator in concrete. Another use is a foaming agent in fire fighting foam.

It can also be very effective as a molluscicide, killing spanish slugs.

Mordants aluminum triacetate and E520 can be prepared from aluminum sulfate, the product formed being determined by the amount of lead(II) acetate used;