General Description
Anhydrous aluminum sulfate is a white crystalline solid. Aluminum sulfate is also obtained as an 18-hydrate Al2(SO4)3.18H2O. Both forms are soluble in water, noncombustible, and nontoxic. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. ALUMINUM SULFATE, SOLID(10043-01-3) is used in paper making, in firefighting foams, and in sewage treatment and water purification.
Reactivity Profile
Aqueous solutions of ALUMINUM SULFATE are acidic. The solid may corrode metals in presence of moisture.
Air & Water Reactions
Dissolves in water with evolution of some heat. creates acidic solutions.
Health Hazard
Inhalation of dust irritates nose and mouth. Ingestion of large doses causes gastric irritation, nausea, vomiting, and purging. Dust irritates eyes and skin.
Potential Exposure
Widely used in the paper industry, in waste and water treatment and treating sewage; in antiperspirants, deodorants; in flame-retardants; in tanning leather, sizing paper; mordant in dyeing, purifying water, waterproofing cloth, clarifying oils and fats; in agricultural pesticides; manufacturing aluminum salts and others
First aid
Move victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy
Shipping
UN3264 Corrosive liquid, acidic, inorganic, n.o.s., Hazard class: 8; Labels: 8-Corrosive material, Technical Name Required. UN3077 Environmentally hazardous substances, solid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous hazardous material, Technical Name Required
Incompatibilities
In aqueous solution, aluminum sulfate forms sulfuric acid; reacts with bases and many other substances. Corrodes metals, some plastics and body tissues, especially in the presence of moisture.
Chemical Properties
Aluminum sulfate is a white powder, often used in water solution. The solution is a strong acid
Waste Disposal
Pretreatment involves hydrolysis followed by neutralization with NaOH. The insoluble aluminum hydroxide formed is removed by filtration and can be heated to decomposition to yield alumina which has valuable industrial applications. The neutral solution of sodium sulfate can be discharged into sewers and waterways as long as its concentration is below the recommended provisional limit of 250 mg/L
Physical properties
White powder; refractive index 1.47; density 2.71 g/cm3; mp 770°C (decomposes); hygroscopic; readily soluble in water (31% at 0°C; solubility increases with temperature 98% in boiling water); soluble in dilute mineral acids; slightly soluble in alcohol.
Occurrence
It occurs in nature in minerals; alunite, KAl3(SO4)2(OH)6and natroalunite, NaAl3(SO4)2(OH)6. The anhydrous salt is used in food applications.
Definition
alunogenite: A mineral form of hydrated aluminium sulphate, Al2(SO4)3.18H2O.
Definition
ChEBI: An aluminium sulfate that contains no water of crystallisation.
Preparation
The anhydrous salt may be obtained by slow and progressive heating of commercial hydrated salt, Al2(SO4)3 ?18H2O. Most water molecules are lost at heating between 250 to 420°C. The last three water molecules are lost between 250 to 420°C at a heating rate of 10°C/min.
Agricultural Uses
Alunogenite is a naturally occurring form of hydrated aluminum sulphate Al2(SO4)318 H2O.
Industrial uses
Aluminum chloride (AlCl3) can be obtained by reacting carbon dioxide and chlorine
with kaolin at high temperatures. It is highly hygroscopic with a specific gravity of 2.3.
It is highly soluble in water and in organic solvents. Similar to aluminum sulfate, aluminum
chloride is used as a co-depressant for calcite, fluorite and dolomite.
Purification Methods
It crystallises from hot dilute H2SO4 (l mL/g) on cooling in ice. When a solution of alumina (Al2O3) in conc H2SO4 is slowly cooled, Al2SO4 17 or 18H2O deposits as a crystalline mass. Al2SO4 17H2O is the stable form in equilibrium with its saturated aqueous solution at 25o [Smith J Am Chem Soc 64 41 1942]. This is purified by dissolving it in a small volume of H2O and adding EtOH until the sulfate readily crystallises from the oily supersaturated solution. It forms Al2O3 16H2O between 0-112o. On gradual heating, the hydrate melts, giving the anhydrous salt at ca 250o. Several hydrates up to 27H2O have been described. Further heating to red heat (~ 600-800o) causes decomposition to Al2O3 + SO3 + SO2 and O2 [Cobb J Soc Chem Ind 29 250 1910]. The ACS reagent is Al2O3 18H2O (98+%).