Introduction

Strict environmental mandates and tight chemical compliance regulations across European and North American markets are forcing industrial formulators to evaluate their raw material selections. Traditional, non-biodegradable chelating agents—most notably Ethylene Diamine Tetraacetic Acid (EDTA) and Nitrilotriacetic Acid (NTA)—face mounting scrutiny under REACH regulations, EU Ecolabel benchmarks, and microplastic guidelines due to their environmental persistence and heavy metal mobilization risks.

Tetrasodium Glutamate Diacetate (GLDA-Na₄) has become the primary, sustainable alternative in industrial chelation. Synthesized from natural L-glutamic acid, GLDA-Na₄ combines rapid biodegradability, zero phosphorus content, and strong multivalent metal ion sequestration. It maintains high stability in extreme thermal and pH environments where traditional chelates degrade.

This comprehensive technical guide details the chemical specifications, comparative binding data, multi-industry applications, global supply market dynamics, and handling procedures for GLDA-Na₄ (CAS 51981-21-6).

Section 1: Chemical Identity & Key Specifications

1.1 CAS Numbers & Synonyms

Tetrasodium Glutamate Diacetate belongs to the aminopolycarboxylate family. It is produced through the carboxymethylation of bio-based L-glutamic acid, followed by neutralization with sodium hydroxide.

• Primary CAS Number: 51981-21-6
• EC / EINECS Number: 257-573-7
• Chemical Name: Tetrasodium N,N-bis(carboxylatomethyl)-L-glutamate
• Molecular Formula: C₉H₉NO₈Na₄
• Molecular Weight: 351.13 g/mol
• Common Industry Synonyms: GLDA, GLDA-Na₄, GLDA-4Na, Tetrasodium Glutamate Diacetate, Dissolvine® GL 38 / GL 47, Chelest CMG-40.

       COONa
         |
       CH-N(CH2COONa)2
         |
       CH2
         |
       CH2
         |
       COONa

1.2 Product Forms & Specifications

Commercial GLDA-Na₄ is supplied primarily as a liquid solution for direct integration into continuous manufacturing, with a solid format available for specialized dry-blend formulations.

• Liquid Grade (38% / 47% Active Content): The primary commercial format is a clear, pale-yellow to amber aqueous solution. It has a density of ≥ 1.20 g/cm³ and a 1% aqueous solution pH between 10.0 and 12.0.
• Solid / Powder Grade (≥ 88% Active Content): Produced via spray drying, this off-white powder is used in dry detergent powders, solid fertilizer mixes, and long-distance transport scenarios to minimize freight volume.
• Critical Purity Specifications: High-grade technical GLDA-Na₄ maintains strict impurity controls, keeping residual NTA-3Na content ≤ 0.1% and free chloride levels ≤ 3.0%.

Section 2: How GLDA Outperforms Traditional Chelating Agents

Selecting an effective chelating agent requires assessing complexation stability constants, operating temperature thresholds, and environmental fate.

                         BIODEGRADABILITY & ECOLOGICAL PROFILE
                      High / Rapid ◄────────────► Low / Persistent
                  ┌──────────────────────────────────────────────┐
  CHELATION       │ GLDA-Na₄               │ EDTA                 │
  PERFORMANCE High│ (186 mg Ca²⁺/g)        │ (158 mg Ca²⁺/g)      │
                  ├────────────────────────┼──────────────────────┤
              Low │ Citrate                │ NTA                  │
                  │                        │ (Carcinogen Risk)    │
                  └────────────────────────┴──────────────────────┘

2.1 Biodegradability: Ready vs. Persistent

Under standard OECD 301D testing guidelines, GLDA-Na₄ achieves >60% biodegradation within 28 days, fulfilling the criteria for "Ready Biodegradability." Because it is synthesized using natural L-glutamic acid, environmental bacteria recognize and metabolize its peptide-like backbone.

Conversely, EDTA resists biological breakdown (<20% degradation over 28 days). It persists in aquatic environments, where it can remobilize toxic heavy metal ions from riverbed sediments into public water sources. Additionally, approximately 56% of the carbon atoms in GLDA-Na₄ originate from renewable plant material, reducing reliance on petrochemical feedstocks.

2.2 Chelation Performance in Harsh Conditions

Recent technical evaluations confirm that GLDA-Na₄ maintains high binding affinity in low-pH and high-temperature environments where legacy aminopolycarboxylates fail:

• Acidic Chelation Efficiency: At low pH levels (pH 1.0 to pH 3.0), GLDA-Na₄ exhibits higher chelation capacity for ferric iron (Fe³⁺) and calcium (Ca²⁺) than HEDTA or EDTA. This capability prevents mineral precipitation during acidizing operations.
• Thermal Endurance: TGA testing confirms that GLDA-Na₄ remains thermally stable up to 170°C, making it suitable for high-temperature industrial boilers, deep-well oilfield stimulation, and geothermal applications.

2.3 Heavy Metal Ion Removal Efficiency

In environmental remediation and sediment treatment, GLDA-Na₄ demonstrates superior extraction efficiency for cadmium (Cd²⁺), copper (Cu²⁺), and nickel (Ni²⁺) compared to EDTA. It forms stable, soluble chelate complexes without leaving toxic, non-degradable chemical residues in treated soil matrixes.

Section 3: Industrial Applications

3.1 Detergents & Industrial Cleaning

GLDA-Na₄ is widely used as a phosphate-free builder and sequestering agent across homecare, commercial laundry, and institutional cleaning markets:

• Automatic Dishwashing (ADW): Sequesters hardness ions (Ca²⁺/Mg²⁺), preventing calcium carbonate deposition, spotting, and filming on glassware.
• Laundry & Surface Cleaners: Neutralizes trace metal ions, enhancing surfactant efficiency, stabilizing sodium percarbonate bleach systems, and preventing fabric encrustation.
• Industry Trends: Major chemical manufacturers continue expanding their GLDA-based product portfolios to support the cleaning sector's shift toward eco-friendly formulations.

[Hard Water Ions (Ca²⁺/Mg²⁺)] + [GLDA-Na₄]
                 │
                 ▼
[Soluble GLDA-Metal Complex] ──> Prevents Scale & Spotting ──> Maximizes Surfactant Performance

3.2 Personal Care & Cosmetics

GLDA-Na₄ is used in personal care formulations as a bio-based chelating agent and preservative booster:

• Formula Stabilization: Binds transition metal ions (Fe³⁺, Cu²⁺) that catalyze the oxidation of unsaturated oils, preserving fragrance, color, and active ingredients.
• Preservative Synergism: By binding stabilizing divalent ions in bacterial cell walls, GLDA-Na₄ weakens microbial membranes, reducing required preservative levels by up to 50%.
• Safety Profile: Non-irritating to skin and eyes, and fully approved under COSMOS, Ecocert, and EU Ecolabel standards for leave-on and rinse-off products.

3.3 Water Treatment & Oilfield Applications

• Acidizing & Matrix Stimulation: Functions as an effective iron-control agent in oil and gas hydraulic fracturing and matrix acidizing. It prevents iron hydroxide precipitation at high downhole temperatures and across acidic-to-neutral pH transitions.
• Scale Control: Serves as a high-temperature scale inhibitor and dispersant in industrial cooling towers and boiler feed systems.

3.4 Agriculture & Soil Remediation

• Micronutrient Complexation: Acts as an environmentally safe ligand for plant micronutrients (Fe, Zn, Mn, Cu), keeping nutrients soluble and bioavailable across various soil pH levels.
• Soil Washing: Used in environmental engineering to extract toxic heavy metals (Cd, Pb, Cu) from contaminated agricultural soils and industrial sediment without damaging soil structure.

3.5 Emerging Applications: Coal Dust Suppression

Recent dust-suppression technologies combine GLDA-Na₄ with specialty surfactants to suppress coal dust. GLDA-Na₄ dissolves inorganic mineral incrustations on coal particle surfaces, increasing surface polarity. This synergistic action reduces the water contact angle down to 18°, enabling rapid coal particle wetting and improved dust control during mining and bulk transport.

Section 4: Global Market & Sourcing Guide

4.1 Market Overview & Growth Trends

The global market for biodegradable chelating agents continues to expand rapidly, driven by environmental regulations restricting EDTA, NTA, and phosphates.

Global Biodegradable Chelates Market:
2025 Market Value:  USD 200M - 400M
Projected CAGR:     6.5% - 9.5% (2025-2030)
GLDA Segment CAGR:  7.5% - 11.0%

• Market Valuation: The broader biodegradable chelating agent market is valued at USD 200M–400M, with projected compound annual growth rates (CAGR) of 6.5% to 9.5%.
• GLDA Sub-segment: The GLDA market segment is projected to grow at a faster CAGR of 7.5% to 11.0%, driven by strong demand across Western Europe, North America, and the Asia-Pacific region.

4.2 Key Manufacturers & Global Supply Options

When establishing supply chains for GLDA-Na₄, procurement managers choose between international brand innovators and high-capacity chemical manufacturers:

• International Producers: BASF SE (Trilon® product lines), Nouryon (Dissolvine® GL series).
• Chinese High-Capacity Manufacturers: Key producers include Shandong Taihe Chemical (offering dedicated multi-thousand-ton annual capacities for GLDA and MGDA), Shandong Yuanlian Chemical / Jining Yuanlian Chemical Technology, and Weifang Dayou Bio-chemical. These manufacturers supply scale liquid and powder options for international export.

4.3 Liquid vs. Powder Sourcing Strategy

• Liquid Grade (38% / 47% Solution): Account for the largest market share. Best suited for regional procurement and continuous liquid blending plants due to lower processing costs, instant water solubility, and simplified automated pumping.
• Powder Grade (≥ 88% Solid): Preferred for dry-blend detergent production, solid fertilizer formulations, and long-distance international shipping where reducing water weight lowers unit transport costs.

Section 5: Storage, Handling & Safety

5.1 Storage Conditions & Handling Guidelines

• Packaging Specs: Typically distributed in 25 kg HDPE drums, 250 kg plastic barrels, 1200 kg IBC totes, or bulk ISO-tanks.
• Storage Environment: Store in tightly closed containers in a cool, dry, well-ventilated location away from direct sunlight, strong acids, and heavy oxidizing agents. Recommended storage temperature range is 5°C to 40°C.
• Shelf Life: Liquid GLDA-Na₄ solutions remain stable for 24 months from manufacture when kept in unopened original packaging.

5.2 Safety & Ecotoxicological Profile

• Ecotoxicity: Non-toxic to aquatic organisms (LC50/EC50 > 100 mg/L), with no bioaccumulation potential.
• Personal Safety: Liquid GLDA-Na₄ is alkaline (pH 10.0–12.0). Standard industrial handling protocols require safety splash goggles, nitrile gloves, and adequate workplace ventilation during bulk transfer operations.
• EDTA Replacement: Can be substituted directly into existing formulations on a 1:1 molar basis, simplifying process adjustments during green product reformulations.