Alum (Papermaking Grade Aluminum Sulfate)
CAS Number: 10043-01-3
Aluminum sulfate (alum) is a classical papermaking chemical used to fix rosin size onto cellulose fibers in acidic papermaking systems, lowering the pH to 4.5–5.5 to promote sizing efficiency. It also acts as a coagulant to precipitate dissolved and colloidal substances from furnish, improving retention and drainage. In modern alkaline mills, polyaluminum chloride (PAC) has largely replaced alum, but alum remains widely used in acidic paper grades.
Technical Specifications
| appearance | White crystalline lumps, granules, or liquid |
| Fe content (%) | ≤ 0.03 |
| pH (1% solution) | 3.0–4.0 |
| Al₂O₃ content (%) | ≥ 16 (liquid) / ≥ 17 (solid) |
Applications
- Rosin size fixation in acidic papermaking systems
- Coagulation of anionic colloidal substances in furnish
- Wastewater treatment coagulant in paper mills
- pH adjustment to acidic range for sizing
- Fixing agent for dyes and wet strength resins
Key Features
- Classical and proven rosin size fixation chemistry
- Effective coagulant for dissolved and colloidal substances
- Low cost and widely available for commodity paper grades
- Available in liquid and solid forms for different handling systems
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CAS Number
10043-01-3
Category
Paper / Pulp ChemicalsAvailability
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