What is the difference between PAA and PAAS?

The main difference between PAA (Polyacrylic Acid) and PAAS (Polyacrylic Acid Sodium Salt) lies in their chemical form and solubility, which affect their performance in different applications, particularly in water treatment, detergents, and scale inhibition. Here's a detailed comparison:

1. Chemical Structure & Form

Property PAA (Polyacrylic Acid) PAAS (Polyacrylic Acid Sodium Salt)

Chemical Formula (C₃H₄O₂)ₙ (acid form) (C₃H₃O₂Na)ₙ (sodium salt form)

Ionic Form Acidic (COOH groups) Neutralized (COONa groups)

pH in Solution Low (~2–4) Higher (~6–8, neutral to slightly alkaline)

2. Solubility & Handling

PAA is less water-soluble in its pure acid form and may require neutralization before use.

PAAS is highly water-soluble due to its sodium salt form, making it easier to handle in liquid formulations.

3. Performance Differences

Application PAA PAAS

Scale Inhibition Effective but may require pH adjustment More readily soluble, better in neutral/alkaline systems

Dispersancy Good for calcium carbonate/sulfate Better in high-pH environments (e.g., detergents)

Corrosion Inhibition Moderate (acidic form can be aggressive) Less corrosive due to neutralized form

Compatibility May react with high-pH solutions More stable in alkaline conditions

4. Common Applications

PAA:

Used in acidic or pH-adjusted systems.

Common in industrial cleaning and boiler water treatment.

PAAS:

Preferred in detergents, textiles, and cooling water systems (where neutral pH is needed).

Often used in liquid formulations due to better solubility.

5. Environmental & Safety

Both are low-toxicity and non-phosphorus, but PAAS is generally preferred in consumer products (e.g., detergents) because it’s less acidic and easier to formulate.

Which One to Choose?

If pH control is needed (acidic systems) → PAA

For neutral/alkaline systems (e.g., detergents, cooling water) → PAAS

For better solubility without pH adjustment → PAAS