Aluminium Sulphate, also spelt Aluminium Sulfate, is a widely-used chemical compound with applications in the purification of drinking water, in water treatment plants, in gardening, in baking powder, as an active ingredient in some antiperspirants, in the dying industry and in paper manufacture. Aluminium Sulphate has the appearance of whitish powder or chunks. The chemical formula of Aluminium Sulphate is Al2(SO4)3. Aluminium Sulphate is sometimes known as Aluminium Alum or Cake Alum.
In the process of water purification, Aluminium Sulphate works by causing impurities to coagulate or stick together. As the particles settle to the bottom of a container, they are clumped together and therefore more easily filtered out. This process is known as flocculation or coagulation.
In gardening, Aluminium Sulphate can be used to change the pH of soil. This is very useful to the gardener who can, for example, alter the colour of Hydrangea plants by adding Aluminium Sulphate to the soil. Naturally, most species of Hydrangea plants produce white flowers but Hydrangea Macrophylla can produce blue, purple, pink or red blooms, depending on the pH of the soil in which they are grown. Generally, Acidic soils produce blue flowers whilst alkaline soils produce pink or purple flowers. Where the soil has a neutral pH, the flowers are usually pale pink. The variation in flower colour is caused by a change in colour of the flower pigments, depending upon the presence of Aluminium in the soil in which they are grown. This type of plant is known as a hyper-accumulating plant. In the dyeing and textiles industries, Aluminium Sulphate works by producing a gelatinous mixture of Aluminium Hydroxide when Aluminium Sulphate is dissolved in a large amount of neutral or slightly alkaline water. This gelatinous substance helps the dye to stick to the fibres in the cloth as the pigment becomes insoluble.
Aluminium Sulphate must be kept away from strong oxidising substances. Aluminium Sulphate is generally stable but sensitive to moisture. Appropriate safety measures should be taken by those persons working with or handling Aluminium Sulphate, including the wearing of protective clothing. The material should only be handled by competent persons. Contact with eyes must be avoided, by the use of safety glasses or safety goggles, as Aluminium Sulphate is a severe eye irritant and can cause serious eye damage. Aluminium Sulphate may be Harmful through ingestion, inhalation or skin absorption.
Aluminium Sulphate is classified as non-Hazardous for air, sea and road freight.