Aluminium chlorohydrate
Encyclopedia
Aluminium chlorohydrate is a group of specific aluminium salt
s having the general formula Al
nCl
(3n-m)(OH
)m. It is used in deodorant
s and antiperspirants and as a coagulant in water purification
.
In water purification, this compound is preferred in some cases because of its high charge, which makes it more effective at destablizing and removing suspended materials than other aluminum salts such as aluminum sulfate, aluminum chloride and various forms of polyaluminum chloride and polyaluminum chlorisulfate, in which the aluminum structure results in a lower net charge than aluminum chlorohydrate. Further, the high degree of neutralization of the HCl results in minimal impact on treated water pH when compared to other aluminum and iron salts.
, X-ray crystallography
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-aluminium complexes.
. A number of aluminium-containing raw materials can be used, including aluminium
metal
, alumina trihydrate, aluminium chloride
, aluminium sulfate
and combinations of these. The products can contain by-product salts, such as sodium
/calcium
/magnesium
chloride
or sulfate
.
Because of the explosion hazard related to hydrogen
produced by the reaction of aluminium metal with hydrochloric acid, the most common industrial practice is to prepare a solution of aluminium chlorohydrate (ACH) by reacting aluminium hydroxide
with hydrochloric acid
. The ACH product is reacted with aluminium 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.
Heather M. Snyder, PhD, 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".
The European Journal of Cancer Prevention stated "underarm shaving with antiperspirant/deodorant use may play a role in breast cancer." The journal Breast Cancer Research proposed a link between breast cancer and the application of cosmetic chemicals in the underarm, including aluminium, with oestrogenic and/or genotoxic properties. Personal care products are potential contributors to the body burden in aluminium and newer evidence has shown that more aluminum is deposited in the outer regions than the inner regions of the breast. But whether differences in the distribution of aluminium are related to higher incidence of tumours in the outer upper region of the breast remains unknown.
al particles present in suspension.
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
s having the general formula Al
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
nCl
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
(3n-m)(OH
Hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and a hydrogen atom held together by a covalent bond, and carrying a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, as a ligand, a nucleophile, and a...
)m. It is used in deodorant
Deodorant
Deodorants are substances applied to the body to affect body odor caused by bacterial growth and the smell associated with bacterial breakdown of perspiration in armpits, feet and other areas of the body. A subgroup of deodorants, antiperspirants, affect odor as well as prevent sweating by...
s and antiperspirants and as a coagulant in water purification
Water purification
Water purification is the process of removing undesirable chemicals, materials, and biological contaminants from contaminated water. The goal is to produce water fit for a specific purpose...
.
In water purification, this compound is preferred in some cases because of its high charge, which makes it more effective at destablizing and removing suspended materials than other aluminum salts such as aluminum sulfate, aluminum chloride and various forms of polyaluminum chloride and polyaluminum chlorisulfate, in which the aluminum structure results in a lower net charge than aluminum chlorohydrate. Further, the high degree of neutralization of the HCl results in minimal impact on treated water pH when compared to other aluminum and iron salts.
Structure
Aluminium chlorohydrate is best described as an inorganic polymer and as such is difficult to structurally characterise. However, techniques such as gel permeation chromatographyGel Permeation Chromatography
Gel permeation chromatography is a type of size exclusion chromatography , that separates analytes on the basis of size. The technique is often used for the analysis of polymers. As a technique, SEC was first developed in 1955 by Lathe and Ruthven. The term gel permeation chromatography can be...
, X-ray crystallography
X-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
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
Keggin structure
Keggin structure is the best known structural form for heteropoly acids. It is the structural form of α–Keggin anions, which have a general formula of [XM12O40]n−, where X is the heteroatom , M is the addenda atom , and O represents oxygen...
structure and that this base unit then undergoes complex transformations to form larger poly-aluminium complexes.
Synthesis
Aluminium chlorohydrate can be commercially manufactured by reacting aluminium with hydrochloric acidHydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
. A number of aluminium-containing raw materials can be used, including aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
, alumina trihydrate, aluminium chloride
Aluminium chloride
Aluminium chloride is the main compound of aluminium and chlorine. It is white, but samples are often contaminated with iron trichloride, giving it a yellow colour. The solid has a low melting and boiling point. It is mainly produced and consumed in the production of aluminium metal, but large...
, aluminium sulfate
Aluminium sulfate
Aluminium sulfate, alternatively spelt aluminum sulfate, aluminium sulphate, or aluminum sulphate; is a chemical compound with the formula Al23...
and combinations of these. The products can contain by-product salts, such as sodium
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...
/calcium
Calcium chloride
Calcium chloride, CaCl2, is a salt of calcium and chlorine. It behaves as a typical ionic halide, and is solid at room temperature. Common applications include brine for refrigeration plants, ice and dust control on roads, and desiccation...
/magnesium
Magnesium chloride
Magnesium chloride is the name for the chemical compounds with the formulas MgCl2 and its various hydrates MgCl2x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine or sea water...
chloride
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
or sulfate
Sulfate
In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
.
Because of the explosion hazard related to hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
produced by the reaction of aluminium metal with hydrochloric acid, the most common industrial practice is to prepare a solution of aluminium chlorohydrate (ACH) by reacting aluminium hydroxide
Aluminium hydroxide
Aluminium hydroxide, Al3, ATH, sometimes erroneously called Hydrate of alumina, is found in nature as the mineral gibbsite and its three, much more rare forms, polymorphs: bayerite, doyleite and nordstrandite. Closely related are aluminium oxide hydroxide, AlO, and aluminium oxide, Al2O3,...
with hydrochloric acid
Hydrochloric acid
Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....
. The ACH product is reacted with aluminium 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.
Common uses and toxicity
The variation most commonly used in deodorants and antiperspirants is Al2Cl(OH)5. Aluminium chlorohydrate is one of the most common active ingredients in commercial antiperspirants and is also often used as a flocculant in water treatment stations.Alzheimer's disease
There have been studies that have found an association between exposure to aluminium and long-term use of antiperspirants and Alzheimer's disease, however the studies also have shown that the association is negligible (less than 1%). As of yet, there is no adequate evidence that neurotoxicity of aluminium leads to progressive dementia and Alzheimer's disease.Heather M. Snyder, PhD, 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. Ted S. Gansler, MD, MBA, the director of medical content for the American Cancer Society, stated "There is no convincing evidence that antiperspirant or deodorant use increases cancer risk".The European Journal of Cancer Prevention stated "underarm shaving with antiperspirant/deodorant use may play a role in breast cancer." The journal Breast Cancer Research proposed a link between breast cancer and the application of cosmetic chemicals in the underarm, including aluminium, with oestrogenic and/or genotoxic properties. Personal care products are potential contributors to the body burden in aluminium and newer evidence has shown that more aluminum is deposited in the outer regions than the inner regions of the breast. But whether differences in the distribution of aluminium are related to higher incidence of tumours in the outer upper region of the breast remains unknown.
Use as coagulant in water purification
Aluminium chlorohydrate is also used as a coagulant in water and waste water treatment process to remove dissolved organic matter and colloidColloid
A colloid is a substance microscopically dispersed evenly throughout another substance.A colloidal system consists of two separate phases: a dispersed phase and a continuous phase . A colloidal system may be solid, liquid, or gaseous.Many familiar substances are colloids, as shown in the chart below...
al particles present in suspension.
Synonyms
- Aluminium hydroxychloride
- Aluminium chlorhydroxide
- Aluminium chloride basic
- Aluminium chlorohydrol
- Polyaluminium chloride