Tetrasodium Iminodisuccinate (IDS-Na₄): The Ultimate Guide to an Eco-Friendly Chelating Agent

Introduction

Tetrasodium Iminodisuccinate (IDS-Na₄) is a leading, environmentally responsible organic chelating agent rapidly replacing traditional options like EDTA and STPP. Gaining significant traction across Europe in industries from home care to textiles and water treatment, IDS-Na₄ combines powerful performance with an excellent ecological profile. This comprehensive guide details its core properties, diverse applications, and undeniable advantages for manufacturers and formulators seeking sustainable solutions.

Core Properties of Tetrasodium Iminodisuccinate

• Chemical Composition & Structure

  • Chemical Name: Tetrasodium Iminodisuccinate

  • Molecular Formula: C₈H₇NNa₄O₈

  • CAS Number: 144538-83-0

  • Appearance: White to faintly yellow crystalline powder, highly soluble in water (solubility ≥500 g/L at 20°C). A 1% aqueous solution has a pH of 10.5-11.5.

• Chelating Performance

  • High Chelating Power: Demonstrates exceptional chelation of metal ions like Ca²⁺, Mg²⁺, and Fe²⁺/³⁺. Its chelation capacity (as CaCO₃) is ≥300 mg/g, comparable to EDTA.

  • Broad pH Applicability: Effective across a wide pH range of 2-12, with outstanding stability, particularly under alkaline conditions (pH > 4). It remains highly active even at low temperatures (20-40°C).

• Environmental & Safety Profile

  • Biodegradability: Readily biodegradable, with a degradation rate exceeding 90% in 28 days (OECD 301 standard), far superior to EDTA (<10%). It exhibits no ecotoxicity.

  • Low Toxicity: Non-irritating in standard skin tests, though prolonged skin contact should be avoided during handling.

• Physical Stability

  • Storage: Solutions may crystallise at 5°C and below. Store in a sealed container in a cool, dry place (Shelf life: 2 years).

  • Chemical Stability: Stable in both strong acid and alkaline media, with optimal performance in alkaline environments.

Key Applications of IDS-Na₄

• Detergents & Cleaners

  • Household & Industrial Detergents: An ideal replacement for phosphates (STPP) and EDTA in laundry liquids, dish soaps, and automatic dishwashing detergents. Maintains high cleaning efficiency in hard water and is compatible with enzyme systems.

  • Industrial Cleaning: Used for cleaning-in-place (CIP) in food processing and for descaling boilers/heat exchangers. Often blended with surfactants and corrosion inhibitors, effective from 20°C to 80°C.

• Textile & Dyeing

  • Pre-treatment: Used in desizing/scouring (1-3 g/L) to prevent fabric yellowing caused by metal ions. Acts as a stabiliser in bleaching (0.5-2 g/L) for controlled peroxide decomposition, minimising fibre damage.

  • Dyeing & Finishing: Enhances reactive dyeing processes (0.5-1.5 g/L) by preventing metal-ion-induced shade variations. Improves soaping fastness and reduces dye re-deposition.

• Water Treatment

  • Cooling Water Systems: Inhibits scale formation (e.g., CaCO₃, MgSiO₃) at 10-50 ppm, pH 7-9, extending equipment lifespan.

  • Reverse Osmosis (RO) Pre-treatment: Chelates Fe³⁺/Al³⁺ at low doses (0.5-1.5 ppm) to prevent membrane fouling and improve efficiency.

  • Wastewater Treatment: Effectively captures and removes heavy metal ions (e.g., Cu²⁺, Ni²⁺) from industrial effluent.

• Personal Care Products

  • Shampoos & Shower Gels: Used as a stabiliser (0.1-1%) to soften water and enhance cleansing performance, effectively replacing EDTA.

  • Toothpaste: Controls calcium precipitation (0.3-0.8%) to prevent tartar formation. Complies with COSMOS organic standards.

• Agriculture & Food Industry

  • Agriculture: Chelates micronutrients (Fe, Zn, Mn) in foliar and fertigation fertilisers (0.05-0.3%), improving plant uptake across a wide pH range (3-9).

  • Food Processing: Approved for use in CIP systems (0.5-1% solution) under FDA 21 CFR 173.315, ensuring food safety.

• Specialised Industrial Applications

  • Pulp & Paper: Serves as a stabiliser in hydrogen peroxide bleaching (0.1-0.5%), preventing resin deposition and enhancing pulp brightness.

  • Coatings & Paints: Delays emulsion gelation (0.2-0.8%) and improves pigment dispersion, enhancing overall paint performance.

Environmental Advantages: IDS-Na₄ vs. Alternatives

Usage and Handling Notes

• Formulation Advice: When used with oxidisers (e.g., sodium percarbonate), sequential addition is recommended. Avoid direct mixing with high concentrations of Al³⁺ or Fe³⁺.

• Storage: Keep container tightly sealed in a cool, dry place. Standard shelf life is 2 years.

Conclusion

Tetrasodium Iminodisuccinate (IDS-Na₄) stands out as the superior, future-proof chelating agent. Its powerful chelation, broad applicability, and proven environmental credentials make it the ideal substitute for traditional chelators like EDTA and STPP. For industries within and exporting to the European market, where environmental regulations are stringent, IDS-Na₄ offers a clear path to high-performance, sustainable, and compliant formulations.