What is PAC?
Poly Aluminium Chloride (PAC) is an inorganic polymer coagulant with the chemical formula [Al2(OH)nCl6-n]m. It has largely replaced traditional aluminum sulfate (alum) in many water treatment applications due to its superior performance.
How PAC Works
PAC works through charge neutralization and bridge aggregation. When added to water, PAC hydrolyzes to form polynuclear aluminum hydroxyl complexes. These positively charged complexes neutralize the negative charges on suspended particles, causing them to aggregate into larger flocs that settle rapidly.
Key Advantages Over Aluminum Sulfate
- Faster floc formation — 2-3x faster settling time
- Wider pH range — Effective from pH 5.0 to 9.0 vs 6.5-7.5 for alum
- Lower dosage — Typically 30-50% less chemical required
- Less sludge — Reduces sludge volume by 20-40%
- Better cold water performance — Maintains effectiveness below 5C
- Lower residual aluminum — Critical for drinking water compliance
PAC Grades and Specifications
| Parameter | Drinking Water Grade | Industrial Grade |
|---|---|---|
| Al2O3 Content | 28-30% | 26-28% |
| Basicity | 40-90% | 40-90% |
| Water Insoluble | under 0.6% | under 1.5% |
| pH (1% solution) | 3.5-5.0 | 3.5-5.0 |
Common Applications
- Municipal drinking water treatment
- Industrial wastewater treatment
- Textile and dye wastewater
- Paper manufacturing
- Oil field water treatment
Need help selecting the right PAC? Contact HydroChemix for technical consultation and a free sample.