Product Details
Alum, predominantly composed of potassium aluminum sulfate dodecahydrate, features antibacterial and astringent properties and is widely applied in Traditional Chinese Medicine (TCM). In TCM theory, it delivers multiple effects: detoxification and deinsectization, dehumidification and antipruritic action, hemostasis and antidiarrheal efficacy, as well as heat-clearing and expectorant benefits. Modern research has further verified its antibacterial and anti-trichomonal activities. It is clinically utilized in TCM to assist in managing conditions including hyperlipidemia, duodenal ulcers, and pulmonary tuberculosis-induced hemoptysis.
In industrial applications, alum serves as a raw material for manufacturing aluminum salts, baking powder, coatings, tanning agents, water clarifiers, dyeing mordants, papermaking additives, and waterproof agents.
It should be noted that when applied as a food additive, alum is barely excreted by the human body and tends to accumulate permanently in tissues. Aluminum contained in alum is not an essential trace element for humans; excessive intake can interfere with the absorption of iron, calcium and other nutrients, potentially triggering symptoms such as anemia and osteoporosis.
Chemical Properties
| English name | Aluminium potassium sulfate dodecahydrate |
| English synonyms | POTASSIUM ALUMINIUM SULFATE 12-WATER;POTASSIUM ALUMINIUM SULFATE DODECAHYDRATE:POTAS SIUM ALUM:POTASSIUM ALUMINUM SULFATE DODECAHYDRATE:POTASSIUM ALUM SULFATE, DODECAHY DRATE;POTASSIUM ALUM DODECAHYDRATE;POTASSIUM AMMONIUM SULFATE;aluminumpotassiumdisulf atedodecahydrate |
| CAS number | 7784-24-9 |
| Molecular formula | AIH8KO5S |
| Molecular weight | 186.2 |
| EINECS number | 616-521-7 |
| Melting point | 92°C (lit.) |
| Boiling point | 200°C |
| Density | 1.757 g/mL at 25°C (lit.) |
| Bulk density | 900 kg/m³ |
| Storage conditions | Store at +5°C to +30°C |
| Solubility | H2O: 0.5M, clear, colorless |
| Form | Solid |
| Specific gravity | 1.757 |
| Color | White |
| Odor | Odorless |
| pH | 3.0-3.5 (25°C, 50 mg/mL in H2O) |
| Water solubility | 140 g/L (20°C) |
| Merck | 14,360 |
| Stability | Stable. Incompatible with steel, aluminum, copper, zinc, alkalis, and strong oxidizers. |
| LogP | -1.031 (est.) |
Alum's main applications cover multiple industries: it serves as a rosin sizing agent in papermaking, a sedimentation aid for turbid water purification, and a film hardener for photographic fixer solutions and photographic paper. It also acts as a foaming auxiliary for foam rubber, as well as a mordant and anti-discharge resist in dyeing and printing processes.
Furthermore, it functions as a water purifier, papermaking sizing agent, dye mordant and retarder. In pharmaceutical fields, it is applied as a preservative, astringent and topical hemostatic agent, and it can also be used as a food additive in relevant scenarios.
