Alum is a group of hydrated double sulfates of aluminum and other elements such as potassium or ammonium. It is widely used in water treatment, food processing, cosmetics, and pharmaceuticals. Below are the general specifications for different types of alum:

Common Types of Alum:

1. Potassium Alum (KAl(SO)12O) - Used in water purification, food, and cosmetics

2. Ammonium Alum (NHAl(SO)12HO) - Used in industrial and water treatment applications

3. Sodium Alum (NaAl(SO)12HO) - Used in food processing and baking powder

4. Ferric Alum (FeAl(SO)12HO) - Used in water treatment and paper manufacturing

Physical Properties:

Appearance: White, transparent crystalline solid or powder

Color: White or colorless (can be slightly yellow in ferric alum)

Odor: Odorless

Taste: Astringent and slightly sweet

Solubility: Soluble in water, insoluble in alcohol

pH (10% Solution): 3.0 - 4.0

Chemical Composition & Purity:

AlO (Aluminum Oxide): 15-18%

SO (Sulfate Content): 50-55%

FeO (Iron Oxide) (For Non-Ferric Alum): Max 0.01%

Water Insoluble Matter: Max 0.1%

Moisture Content: Max 5%

Purity: Min 99%

Microbiological Standards (For Food & Cosmetic Grade Alum):

Total Plate Count: Max 10,000 CFU/g

Yeast & Mold: Max 100 CFU/g

Coliforms: <10 CFU/g

E. Coli & Salmonella: Absent

Contaminants & Adulterants:

Heavy Metals:

Lead (Pb): <0.2 ppm

Cadmium (Cd): <0.1 ppm

Arsenic (As): <0.1 ppm

Mercury (Hg): <0.05 ppm

Pesticide Residues: Not detected

Artificial Additives & Preservatives: Must be absent

Applications of Alum:

Water Treatment: Used in coagulation and flocculation for purification

Food Industry: Used as a food additive (E522) in pickles, baking powder, and cheese processing

Cosmetics & Personal Care: Used in deodorants, aftershaves, and skin tightening products

Pharmaceuticals & Ayurveda: Used in antiseptic and astringent medicines

Paper & Textile Industry: Used for sizing paper and as a mordant in dyeing fabrics