Dispersant: Sodium Salt of Polyaspartic Acid (PASP)

Sodium Salt of Polyaspartic Acid (PASP) is a water-soluble, biodegradable polymer that represents another major milestone in green chemical water treatment and industrial dispersants.

Much like PESA, PASP is completely free of phosphorus and nitrogen-induced eutrophication risks, making it highly valued as an eco-friendly scale inhibitor, dispersant, and agricultural nutrient synergist.

1. Chemical Structure & Character

PASP is a synthetic polyamino acid. Its backbone contains recurring peptide bonds (amide linkages), closely mimicking the structure of natural proteins.

Structural Units: It typically consists of a mixture of alpha and beta-linkages of sodium L-aspartate.

Functional Groups: The structure is highly populated with active carboxylate groups (-COONa) branching off the main peptide chain.

Key Properties:

Exceptional Biodegradability: Because of its protein-like peptide backbone, PASP is easily and completely broken down by environmental microorganisms into harmless end products (water, carbon dioxide, and biomass).

High Dispersion Capacity: The dense negative charge density from the carboxylate groups gives it superior particulate dispersion capabilities compared to many traditional small-molecule phosphonates.

Non-Toxic & Non-Irritating: Safe to handle and safe for aquatic ecosystems.

2. Dual-Action Mechanism: Scale Inhibition & Dispersion

PASP prevents fouling and deposition through a combination of chemical and electrostatic actions:

Scale Inhibition

Chelation & Solubilization: The carboxylate oxygen atoms form stable coordinate bonds with divalent metal ions like Ca2+, Mg2+, Ba2+, and Sr²⁺, keeping them soluble even in supersaturated conditions.

Crystal Distortions: PASP adsorbs directly onto active growth sites of micro-scale crystals (such as calcium carbonate or calcium sulfate). This alters the crystal growth kinetics, causing the scale to form loose, amorphous, non-adherent structures rather than hard, dense crystal lattices.

Dispersant Performance

Electrostatic Repulsion & Steric Hindrance: PASP adsorbs onto the surfaces of suspended solids, silt, clay, iron oxides, and insoluble micro-crystals. This imparts a h3 negative surface charge to the particles. The resulting electrostatic repulsion (zeta potential increase) and steric hindrance prevent the particles from agglomerating, keeping them suspended in the water column so they can be easily flushed or filtered out.

3. Core Industrial Applications

A. Industrial Water Management

PASP is widely utilized in circulating cool water systems, oilfield water flooding, and reverse osmosis (RO).

High-Hardness Systems: It exhibits h3 scale inhibition for CaCO₃ and CaSO₄.

Synergistic Blends: It is frequently compounded with zinc salts, PESA, or low-phosphorus phosphonates to build robust, environmentally compliant corrosion and scale inhibitor packages.

B. Textile Dyeing & Auxiliaries

In textile wet processing, PASP functions as an excellent chelating dispersant.

Dye Dispersion: It prevents the agglomeration of disperse, reactive, or direct dyes, ensuring uniform leveling and preventing dye spots on fabrics.

Water Softening: It chelates hardness ions in the process water without demetallizing metal-complex dyes.

C. Agriculture (Nutrient Synergist)

Due to its exceptional chelating properties and safety profile, PASP is widely added to fertilizers (like urea or compound fertilizers). It chelates micronutrients in the soil, preventing them from fixing into insoluble forms and significantly improving crop uptake of nitrogen, phosphorus, and potassium.

4. Typical Technical Specifications

Parameter Specification (Liquid Grade)

Appearance Amber to dark brown clear liquid

Active Component (Solid Content)      ≥40.0%

Density (20℃)        ≥1.20g/cm³

pH (1% water solution)       9.0 - 11.0

Free Monomer (as Aspartic Acid)    ≤2.0%