Advantages and disadvantages of Polyaspartic acid (sodium) (PASP)

Polyaspartic acid (sodium) (PASP) is a green and biodegradable water treatment agent with scale inhibition, corrosion inhibition and dispersibility. The following is a comprehensive analysis of its advantages and disadvantages and typical application suggestions:

I Core advantages of PASP

1. Outstanding environmental performance

Biodegradability:

The biodegradation rate within 28 days is >70%, which meets the OECD 301B standard and is far superior to traditional phosphorus-based agents (such as HEDP).

No phosphorus and no nitrogen:

Avoids the risk of eutrophication and is suitable for areas with strict environmental regulations (such as EU REACH).

2. Excellent high temperature resistance

Stable temperature range:

Short-term tolerance ≤120℃, long-term use ≤90℃ (better than PESA but slightly inferior to AA/AMPS).

High temperature scale inhibition mechanism:

The carboxyl group in the molecule forms a chelate with high thermal stability with the metal ion.

3. Broad-spectrum scale inhibition

Effective scale types:

CaCO₃, CaSO₄, BaSO₄ (weak effect on Ca₃(PO₄)₂, need to be compounded with phosphonates).

Low concentration and high efficiency:

5~10 ppm can achieve more than 80% scale inhibition rate (medium and low hardness water quality).

4. Compatibility and compounding

Synergy with a variety of agents

Compounded with AA/AMPS to improve salt tolerance (applicable to TDS > 10,000 mg/L);

Compounded with zinc salts to enhance corrosion inhibition effect (such as Zn²⁺+PASP corrosion inhibition rate increased by 30%).

 II The main disadvantages of PASP

1. High cost

Raw materials and processes:

Synthesis requires aspartic acid monomers, the price is 1.5~2 times that of AA/AMPS, which restricts large-scale application.

2. Limited ability to resist high-valent ions

Ca²⁺/Mg²⁺ tolerance

When Ca²⁺ > 800 mg/L, the scale inhibition rate drops significantly (sulfonic acid copolymers need to be compounded).

3. Narrow pH application range

Optimal pH range: 7~9, easy to precipitate and fail under strong acid (pH<4) or strong alkali (pH>11) conditions.

4. Poor calcium phosphate scale inhibition effect

Limitations: Almost no inhibitory effect on PO₄³⁻, needs to rely on phosphonates or polycarboxylic acids for compounding.

III Comparison of PASP with other scale inhibitors, application scenario recommendations

1. PASP Recommended use scenarios

Environmentally sensitive fields; Seawater desalination, ecological protection area circulating water system (biodegradability required); Medium-high temperature and low hardness water quality; Geothermal reinjection water (80~100℃); food industry cooling water.

2. Scenarios that require caution or compounding

High calcium/high phosphate water quality, need to compound HEDP or AA/AMPS.

Strong acid/base system, use sulfonated copolymer or phosphinocarboxylic acid instead.

IV Performance optimization scheme

1. Compounding and enhancing efficiency 

PASP + AA/AMPS (3:1): Improve salt tolerance to TDS > 20,000 mg/L.

PASP + sodium molybdate: Corrosion inhibition rate increased to 90% (60℃ carbon steel system).

2. Process adjustment

Move the addition point forward in the high temperature section (>100℃), and use corrosion inhibitor to extend the action time.

Summary

Polyaspartic acid (sodium) (PASP) is a benchmark product for green water treatment, suitable for environmental protection priority, medium and low temperature, medium and low hardness water quality, but it needs to rely on compounding technology under high calcium, high phosphate or extreme pH conditions. The cost problem can be alleviated through large-scale production or compounding with cheap agents.