21645-51-2 Usage
Description
Aluminum hydroxide is a white crystalline compound, Al(OH)3, that is insoluble in water but soluble in acid or alkali. It is a typical amphoteric hydroxide and can be transformed into alumina after being heated in the air for dehydration. Aluminum hydroxide is a widely used chemical product with various applications across different industries.
Uses
1. Chemical raw materials:
Aluminum hydroxide is used as an important raw material for the preparation of aluminum salts, such as barium aluminate and aluminum sulfate, due to its large-scale production, adequate raw materials, high product purity, and good solubility in acid.
2. Flame retardants:
Used in Plastics and Rubber Industry:
Aluminum hydroxide is used as an ideal flame retardant filler for plastics, unsaturated polyester, and rubber due to its filling, flame retardant, and smoke-eliminating functions, as well as its non-toxic property.
3. Ceramics:
Used in Ceramics Industry:
Aluminum hydroxide can transform into alumina, which is an important material for the synthesis of ceramics. It is used to control the phase formation of the composite through activation and crystallization process controlling.
4. Sewage treatment:
Aluminum hydroxide is used in water treatment to precipitate toxic heavy metals in sewage by coprecipitation method, achieving water purification effects. It has a high specific surface area, allowing it to adsorb colloids, suspended solids, dyes, and organic substances in sewage.
5. Medicine:
Used in Pharmaceutical Industry:
Aluminum hydroxide is used as a traditional medicine for the treatment of stomach ailments, as it can neutralize gastric acid and is non-toxic. It is also used as an adjuvant to improve the immunogenicity of vaccines by adsorbing antigens on its surface for slow release and extended efficacy.
6. Catalyst carrier:
Aluminum hydroxide can be used as a catalyst carrier for various applications, such as the hydrogenation of unsaturated carbonyl compounds and the preparation of fullerenes, by controlling the temperature, concentration, and pH of the reactants to obtain different surface area, pore volume, pore structure, and crystal structure.
7. Paper industry:
Used in Paper Industry:
Aluminum hydroxide, with its high whiteness, ultrafine particle size, and complete crystal form, is used as an additive coating and resin to improve the whiteness, opacity, smoothness, and ink absorption of coated paper.
Additional Uses:
Aluminum hydroxide is used as an active medicament in antacid formulations, as well as in the manufacturing of lake colors, inks, glass, effluent treatment, and fire retardants.
It is used as a humectant, skin softener, and viscosity control agent in the cosmetic industry, often found in facial masks and makeup preparations.
It serves as an absorbent, desiccant powder, filler in paper, plastics, rubber, and cosmetics, and is used in chromatography, manufacturing of glass, and as a smoke suppressant and mordant dye.
Aluminum hydroxide is also used as a Claus catalyst support for waterproof fabrics and is an important starting material for the preparation of other aluminum compounds, calcined alumina, aluminum sulfate, polyaluminum chloride, zeolites, sodium aluminate, activated alumina, and aluminum nitrate.
Physical and chemical properties
Chemical formula: Al(OH)3. White crystal. Density: 2.42g?cm-3. Dehydration temperature: 300℃. Insoluble in water. Aluminum hydroxide is a typical amphoteric hydroxide, and it can be soluble in acid to form aluminum salt and soluble in alkali to form aluminate.
The overview, physical and chemical properties, preparation methods and applications of the aluminum hydroxide are edited by the Eastern editor of lookchem. (2016-12-01)
Preparation
1. Industrial production methods
Industrial production methods include Bayer and sintering methods.
(1) Bayer method
97% of the bauxite ores produced worldwide each year are treated with Bayer method to obtain alumina. The Bayer method consists of two main processes:
1) Treat bauxite with caustic soda solution to transform the alumina in the ore into sodium aluminate.
2) Decompose the cooled sodium aluminate solution by stirring and then separate by filtration to obtain aluminum hydroxide product.
The caustic soda after decomposition can be recycled.
(2) Sintering method
In industrial aluminum, the sintering method is mainly used for high silica bauxite, namely Al2O3/SiO2 <7. The sintering method includes the following three steps:
1) Mix the bauxite and sodium carbonate solution by a certain percentage for sintering.
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2) Eluviate the sintered bauxite with sodium carbonate solution to prepare sodium aluminate.
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3) Introduce CO2 gas into the sodium aluminate solution to form aluminum hydroxide. At the same time, caustic soda can be transformed into sodium carbonate and then used repeatedly in the sintering process.
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?2. Hydrothermal method
Aluminum hydroxide synthesized by hydrothermal method has the advantages of high purity, small particle size, uniform distribution, easily-controlling crystal form and simple operation. Therefore, this method is widely used in the process of synthesis of aluminum hydroxide.
3. Sol-gel method
Sol-gel method is commonly used for the preparation of ultra-fine aluminum hydroxide. The most common sol-gel method for the preparation of aluminum hydroxide is the hydrolysis of aluminum salts and alkoxides in water, the mechanism of which is divided into two steps: 1)-OR group is hydrolyzed to produce-OH; 2) Al3+ reacts with –OH to separate aluminum hydroxide precipitation out.
4. Carbon fractionation
Carbon fractionation is a method that is performed as follows: Introduce CO2 gas into sodium metaaluminate solution to make aluminum hydroxide precipitate down and control the size and morphology of products by adjusting the pH value and CO2 concentration.
5. Microemulsion method
Microemulsion is typically composed of surfactants, cosurfactants, solvents and water (or aqueous solution). Microemulsion has many excellent properties such as ultra-low interfacial tension and high solubilization capacity. The preparation of nano-materials by microemulsion technology can precisely control the crystal growth process of nano-materials, and the micro-emulsion ball can encapsulate the crystal particles to effectively prevent the agglomeration of nano-particles.
Main application
(1) Used for preparing waterproof fabrics, inks, glass, paper fillers, mordant, purifying agent, various aluminum salts, etc.
(2) Widely used for plastics, rubber, resin, paint, paint and so on
(3) Used for supporting catalyst and separating the vapor liquid
(4) Used in the industries of petroleum, chemical, fertilizer, natural gas and environmental protection for increasing the gas or liquid distribution points and protecting the low-strength catalyst.
(5) Used as mordants and analysis reagents.
(6) Used as the thickener for ink and the raw materials for manufacturing aluminum salt, enamel, ceramics, glassware and lubricant. Also used for the preparation of various catalyst carrier. Aluminum hydroxide gel can be used for the treatment of duodenal ulcer, gastric ulcer and hyperacidity embolism. In addition, also used in waterproof fabrics, paper fillers, mordant and purifying agent.
(7) Used for printing inks, painting pigments, crayons and rubber packing.
(8) Uses in waterproof fabric, ink, glassware, paper packing, mordant, purifying agent and also used in aluminum salt, lubricant manufacture.
(9) Used for the gravimetric determination of potassium content. Used as adsorbents, emulsifiers, ion exchangers, chromatographic analytes and mordants. Used for the preparation of refractory, glass and pottery, as well as precipitation pigment and waterproof fabric. Also used for the manufacture of aluminum salts.
Production method
(1) Add alkaline solution to the aluminum sulfate solution under stirring to form precipitation. The precipitation is washed, filtered and dried at low temperature, and then crushed to obtain the finished product. The dewatered paste may also be used as the product directly. The solution concentration, reaction temperature and drying temperature in the preparation process all affect the product quality.
(2) Ammonium bicarbonate method: sulfuric acid reacts with aluminum powder or aluminum ash to generate aluminum sulfate, and then aluminum sulfate perform metathesis reaction with ammonium bicarbonate to obtain aluminum hydroxide.
2Al(OH)3+3H2SO4→A12(SO4)3+6H2O
A12(SO4)3+6NH4HCO3→2AI(OH)3++3(NH4)2SO4+6CO2↑
Sodium aluminate method: caustic soda and aluminum ash react at the ratio of 2: 1 at 100 ° C to obtain sodium aluminate solution. Sulfuric acid and aluminum ash react at the ratio of 1.25: 1 at 110 ° C to produce aluminum sulfate solution. Then, the sodium aluminate solution and the aluminum sulfate solution are neutralized to pH 6.5 to produce aluminum hydroxide precipitate. The obtained precipitate is washed with water, filtered and dried at 70-80℃ for 12 hours, and then crushed to prepare the aluminum hydroxide product.
A12O3+2NaOH→2NaAO2+H2O
Al2O3+3H2SO4→A12(SO4)3+3H2O
6NaAIO2+A12(SO4)3+12H2O→8Al(OH)3↓+3Na2SO4
Recovery method: the recycled aluminum chloride is dissolved in water, decolorized with activated carbon and filtered to remove impurities, and then react with sodium carbonate to produce raw aluminum hydroxide. The raw products are filtered, washed and dried to obtain the final aluminum hydroxide products.
2A1C13+3Na2CO3+3H2O→2AI(OH)3↓+6NaCl+3CO2↑
Solubility in water
Solubility in 100 ml of water: 0.0001 g/20℃
Toxicity
The toxicity of aluminum mainly includes two aspects: the first is the mechanical stimulation to lung tissue; the second is to make protein precipitation and form fiber-like irreversible protein compounds with non-inflammatory performance. The inhalation of aluminum dust can damage the lungs to cause bauxite lung, the chronic symptoms of which have weight loss, easy fatigue, difficult breathing and cough. Aluminum hydroxide is more likely to cause alveolar epithelial hyperplasia than aluminum.The maximum allowable concentration of aluminum hydroxide is 6 mg/m3.
Small trauma can be first treated with alcohol and gasoline, and then covered with non-toxic dressing; large wound can be excised and sutured, and then treated with sulfonamides and penicillin therapy. People working in dusty places should wear gas masks, protective glasses and dust protective overalls to protect the skin and eyes. In addition, every year people should attend a regular physical examination.
Hazards & Safety Information
Category? Toxic substances
Toxicity classification? High toxic
Acute toxicity?? celiac-rat LD50: 150 mg/kg
Storage and transportation characteristics?? Ventilation; Low temperature; dry
Fire extinguishing agent?? dry powder, foam, sand, carbon dioxide; fog water
Occupational Standard?? TWA 2mg (Al)/m3
Production Methods
Aluminum hydroxide adjuvant is prepared by the precipitation of a
soluble aluminum salt by an alkali hydroxide, or the precipitation of
an alkali aluminate by acid.
Flammability and Explosibility
Nonflammable
Pharmaceutical Applications
Aluminium hydroxide (Al(OH)3) has several medical applications. It is used as an antacid for treating
heartburn as well as acid indigestion (reflux oesophagitis). It is also known to have healing properties of peptic ulcers. In patients suffering from kidney failure, who show elevated serum phosphate levels (hyperphosphataemia),
Al(OH)3 is used as a phosphate binder.
Al(OH)3 is an amphoteric compound , which means it can react as a base or as an
acid. In its application as an anti-acid, Al(OH)3 reacts with any excess stomach acid (mainly HCl) with the
formation of AlCl3 and water .
Al(OH)3 + 3HCl → AlCl3 + 3H2O
Al(OH)3 is known to cause constipation, so formulations of anti-acids often include a combination with
Mg2+ antacids. Usually, oral antifoaming agents, such as simethicone, are added in order to reduce bloating and discomfort/pain.
Pharmaceutical Applications
Aluminum hydroxide adjuvant is used in parenteral human and
veterinary vaccines.It activates Th2 immune responses, including
IgG and IgE antibody responses. It is also used for the isolation of
certain serum components such as blood clotting factors.
Clinical Use
Phosphate binding agent
Antacid
Safety Profile
Poison by intraperitoneal route. Human systemic effects by ingestion: fever, osteomalacia, and gastrointestinal effects. When coprecipitated with bismuth hydroxide and reduced by H2, it is violently flammable in air. Incompatible with chlorinated rubber.
Safety
Aluminum hydroxide adjuvant is intended for use in parenteral
vaccines and is generally regarded as nontoxic. It may cause mild
irritation, dryness, and dermatitis on skin contact. On eye contact,
aluminum hydroxide adjuvant may also cause redness, conjunctivitis,
and short-term mild irritation. Ingestion of large amounts may
cause gastrointestinal irritation with nausea, vomiting, and
constipation. Inhalation of the dried product may cause respiratory
irritation and cough. Type I hypersensitivity reactions following
parenteral administration have been reported.
Veterinary Drugs and Treatments
Orally administered aluminum hydroxide is used to reduce hyperphosphatemia
in patients with renal failure.
Drug interactions
Potentially hazardous interactions with other drugs
Cytotoxics: concentration of dasatinib and erlotinib
possibly reduced - give at least 4 hours before or 2
hours after erlotinib.
Metabolism
Aluminum hydroxide or oxide is slowly solubilised in
the stomach and reacts with hydrochloric acid to form
aluminium chloride and water. In addition to forming
aluminium chloride, dihydroxyaluminium sodium
carbonate and aluminium carbonate form carbon dioxide,
and aluminium phosphate forms phosphoric acid. About
17-30% of the aluminium chloride formed is absorbed
and is rapidly excreted by the kidneys in patients with
normal renal function.
Aluminium-containing antacids also combine with
dietary phosphate in the intestine forming insoluble,
nonabsorbable aluminium phosphate which is excreted in
the faeces.
storage
Aluminum hydroxide adjuvant is stable for at least 2 years when
stored at 4–308℃ in well-sealed inert containers. It must not be
allowed to freeze as the hydrated colloid structure will be
irreversibly damaged.
Incompatibilities
When exposed to phosphate, carbonate, sulfate, or borate anions,
the point of zero charge for aluminum hydroxide adjuvant
decreases.
Regulatory Status
GRAS listed. Accepted for use in human and veterinary parenteral
vaccines in Europe and the USA. The limits for use in human
vaccines are 0.85 mg aluminum/dose (FDA) and 1.25 mg aluminum/
dose (WHO). There are no established limits for use in
veterinary vaccines. Reported in the EPA TSCA Inventory.
Check Digit Verification of cas no
The CAS Registry Mumber 21645-51-2 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,1,6,4 and 5 respectively; the second part has 2 digits, 5 and 1 respectively.
Calculate Digit Verification of CAS Registry Number 21645-51:
(7*2)+(6*1)+(5*6)+(4*4)+(3*5)+(2*5)+(1*1)=92
92 % 10 = 2
So 21645-51-2 is a valid CAS Registry Number.
InChI:InChI=1/Al.3H2O/h;3*1H2/q+3;;;
