Aluminium chlorohydrate is a group of water-soluble, specific aluminium

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

s having the general formula Al_n Cl_(3n-m)( OH)_m. It is used in cosmetics as an

antiperspirant A deodorant is a substance applied to the body to prevent or mask body odor due to bacterial breakdown of perspiration or vaginal secretions, for example in the armpits, groin, or feet. A subclass of deodorants, called antiperspirants, preven ...

and as a coagulant in

water purification Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for hu ...

. In water purification, this compound is preferred in some cases because of its high charge, which makes it more effective at destabilizing and removing suspended materials than other aluminium salts such as

aluminium sulfate Aluminium sulfate is a salt with the formula Al2 (SO4)3. It is soluble in water and is mainly used as a coagulating agent (promoting particle collision by neutralizing charge) in the purification of drinking water and wastewater treatment plan ...

, aluminium chloride and various forms of polyaluminium chloride (PAC) and polyaluminium chlorisulfate, in which the aluminium structure results in a lower net charge than aluminium chlorohydrate. Further, the high degree of neutralization of the

HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a s ...

results in minimal impact on treated water pH when compared to other aluminium and iron salts.

Uses

Aluminum chlorohydrate is one of the most common active ingredients in commercial

s. The variation most commonly used in deodorants and antiperspirants is Al₂Cl(OH)₅. Aluminum chlorohydrate is also used as a coagulant in water and wastewater treatment processes to remove

dissolved organic matter Dissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called parti ...

and

colloid A colloid is a mixture in which one substance consisting of microscopically dispersed insoluble particles is suspended throughout another substance. Some definitions specify that the particles must be dispersed in a liquid, while others extend ...

al particles present in suspension.

Safety

The U.S.

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

considers the use of aluminum chlorohydrate in antiperspirants to be safe and it is permitted in concentrations up to 25%.

Alzheimer's disease

Studies have found only a negligible association between exposure to and long-term use of antiperspirants and

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As ...

. There is no adequate evidence that exposure to aluminium in antiperspirants leads to progressive dementia and Alzheimer's disease. Heather M. Snyder, the senior associate director of medical and scientific relations for the Alzheimer's Association, has stated, "There was a lot of research that looked at the link between Alzheimer's and aluminum, and there hasn't been any definitive evidence to suggest there is a link".

Breast cancer

The International Journal of Fertility and Women's Medicine found no evidence that certain chemicals used in underarm cosmetics increase the risk of

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or ...

. Ted S. Gansler, the director of medical content for the

American Cancer Society The American Cancer Society (ACS) is a nationwide voluntary health organization dedicated to eliminating cancer. Established in 1913, the society is organized into six geographical regions of both medical and lay volunteers operating in more than ...

, stated "There is no convincing evidence that antiperspirant or deodorant use increases cancer risk". However, there is continued concern over the use of aluminum chlorohydrate in cosmetics as the risk of toxic build up over time has not been ruled out. The Scientific Committee on Consumer Safety (SCCS) is currently designing a study to analyse the build up of aluminum chlorohydrate via dermal penetration to assess the risk of toxic build up.

Structure

Aluminum chlorohydrate is best described as an inorganic polymer and as such is difficult to structurally characterize. However, techniques such as gel permeation chromatography,

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

and ²⁷Al-NMR have been used in research by various groups including that of Nazar and Laden to show that the material is based on Al₁₃ units with a Keggin ion structure and that this base unit then undergoes complex transformations to form larger poly-aluminum complexes.

Synthesis

Aluminum chlorohydrate can be commercially manufactured by reacting aluminum with

hydrochloric acid Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the dige ...

. A number of aluminum-containing raw materials can be used, including

aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It ha ...

metal A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...

, alumina trihydrate, aluminum chloride,

aluminum sulfate Aluminium sulfate is a salt with the formula Al2 (SO4)3. It is soluble in water and is mainly used as a coagulating agent (promoting particle collision by neutralizing charge) in the purification of drinking water and wastewater treatment plan ...

and combinations of these. The products can contain by-product salts, such as

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar ...

/ magnesium chloride or

sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

. Because of the explosion hazard related to

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...

produced by the reaction of aluminum metal with hydrochloric acid, the most common industrial practice is to prepare a solution of aluminum chlorohydrate (ACH) by reacting aluminum hydroxide with

. The ACH product is reacted with aluminum ingots at 100 °C using steam in an open mixing tank. The Al to ACH ratio and the time of reaction allowed determines the polymer form of the PAC n to m ratio.

References

{{DEFAULTSORT:Aluminum Chlorohydrate Aluminium compounds Chlorides