How to Buy Polyaluminium Chloride (PAC): Specs, Al2O3 and Basicity

How to Buy Polyaluminium Chloride (PAC): Specs, Al₂O₃ and Basicity

PAC (polyaluminium chloride, CAS 1327-41-9) is not a single specification – two suppliers can quote “PAC” at very different quality and price. To buy it well you need to fix three things: the Al₂O₃ content, the basicity and the grade (drinking water or industrial). This guide covers what to confirm on a PAC enquiry and how to compare quotations like-for-like.

1. The two numbers that matter most

Parameter	What it means	Typical range
Al₂O₃ content	The active coagulant you are paying for	Solid about 28-31%; liquid about 10-11%
Basicity	Degree of pre-hydrolysis (OH/Al ratio)	About 40-80%, commonly 60-85%

Because PAC is sold on Al₂O₃ content, a “cheaper” quote can simply be a weaker product. Always compare on cost per kg of Al₂O₃, not per tonne of product.

2. Full specification to request

Parameter	Why it matters
Al₂O₃ content	Sets the dose and the true cost
Basicity	Affects performance and pH behaviour
pH (1% solution)	About 3.5-5.0; indicates the product form and how it will behave in dosing
Water-insoluble matter	Low for good grades; high insolubles mean dosing and sludge problems
Heavy metals (Pb, As, etc.)	Critical for drinking-water grade
Appearance	White/light for drinking water; yellow/pale yellow for industrial

3. Drinking-water grade vs industrial grade

Grade	Key difference	Use
Drinking-water grade	Tight heavy-metal limits; light colour	Potable water supply
Industrial grade	Meets an industrial spec; lower cost	Wastewater, industrial, mining, paper

If the treated water is for drinking, you need the drinking-water grade and its paperwork; do not substitute industrial grade on price.

4. Solid or liquid?

Form	Advantages	Considerations
Solid (powder/granular)	Cheaper to ship; long shelf life	Needs dissolving; dust and handling
Liquid	Ready to dose; no make-up	Higher freight (water); shorter storage life

For export markets, solid is common; for large plants with dosing systems, liquid can be more convenient. Decide by freight economics and your dosing setup.

5. Packaging and documentation

Solid: 25 kg bags, 1000 kg jumbo bags.
Liquid: IBCs, bulk/tanker.
Documents: specification sheet, certificate of analysis (COA) and safety data sheet (SDS) per batch; third-party inspection (SGS/BV) on request.

6. Dosage: confirm by jar test

The dose depends on turbidity, alkalinity, pH, temperature and the target. As a starting point it is in the range of a few to a few tens of mg/L, but always set it by jar test on your water and confirm settled turbidity, residual aluminium and sludge volume.

7. Supplier checklist

States Al₂O₃ content and basicity in writing.
Identifies the grade (drinking water or industrial).
Provides per-batch COA and SDS.
Quotes on cost per kg Al₂O₃, not product weight alone.
Confirms form, packaging and delivery terms.

Frequently Asked Questions

What does basicity mean in PAC?

It is the degree of pre-hydrolysis (the OH to Al ratio). Higher basicity generally means better performance in many waters, but the right value depends on your water – confirm it by jar test.

Is PAC bought on Al₂O₃ content?

Yes. That is the active you are paying for, so compare quotes on cost per kg of Al₂O₃, not per tonne of product.

What is the difference between drinking-water and industrial PAC?

The heavy-metal limits and colour. Drinking-water grade meets tight limits and is lighter in colour; industrial grade meets an industrial spec and costs less.