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Views: 0 Author: Site Editor Publish Time: 2026-08-04 Origin: Site
Disodium edetate dihydrate (commonly known as EDTA disodium dihydrate, EDTA-2Na, or disodium EDTA) is one of the most widely used chelating agents in the world. It is an aminopolycarboxylic acid salt that sequesters metal ions — primarily calcium, magnesium, iron, copper, and manganese — making them chemically inactive. This single property underpins its use across water treatment, food preservation, cleaning products, agriculture, cosmetics, and industrial manufacturing.
This guide covers everything professionals and procurement teams need to know about disodium edetate dihydrate, with zero medical or pharmaceutical content.
Property | Detail |
IUPAC Name | Disodium 2-({2-[bis(carboxymethyl)amino]ethyl}(carboxymethyl)amino)acetate dihydrate |
Common Names | Disodium EDTA, EDTA disodium dihydrate, EDTA-2Na, Edetate disodium |
CAS Number | 6381-92-6 (dihydrate) / 139-33-3 (anhydrous) |
Molecular Formula | C₁₀H₁₄N₂Na₂O₈ · 2H₂O |
Molecular Weight | 372.24 g/mol |
Appearance | White crystalline powder or granules |
Solubility | Freely soluble in water (~10 g/100 mL at 20°C); practically insoluble in ethanol |
pH (1% aqueous solution) | 4.0 – 5.5 |
E Number (Food Additive) | E386 |
INS Number | 386 |
Chelation Value | ~269 mg CaCO₃ per gram (theoretical) |
Stability | Stable under normal conditions; hygroscopic — store in a cool, dry place |
Disodium EDTA dihydrate belongs to the aminopolycarboxylate family. Its molecular structure features six donor atoms — two amine nitrogen atoms and four carboxylate oxygen atoms — that can simultaneously coordinate with a single metal ion. This makes EDTA a hexadentate ligand, forming exceptionally stable 1:1 complexes with most multivalent metal cations.
The stability of EDTA-metal complexes is pH-dependent. At lower pH, protonation of the amine and carboxylate groups reduces chelating capacity. Optimal chelation occurs in the pH range of 4 to 12, with the disodium salt performing best in slightly acidic to neutral environments.
Disodium EDTA is a cornerstone chemical in industrial and municipal water treatment:
Application | Function |
Boiler water treatment | Sequesters Ca²⁺ and Mg²⁺ to prevent scale formation on heat-exchange surfaces |
Cooling water systems | Controls metal-ion-catalyzed corrosion and scale deposition |
Reverse osmosis (RO) pretreatment | Binds hardness ions to protect membranes from scaling |
Industrial wastewater | Chelates heavy metals (Cu, Zn, Ni, Pb) for precipitation or recovery |
Metal cleaning & descaling | Dissolves iron oxide and calcium carbonate deposits from equipment |
Typical dosage: 2–50 mg/L depending on water hardness and system design.
In household, institutional, and industrial cleaning formulations, disodium EDTA enhances performance by:
Softening water
● — binding Ca²⁺ and Mg²⁺ so surfactants can work at full efficiency
Preventing soap scum
● — keeping metal soaps in solution rather than depositing on surfaces
Improving stain removal
● — chelating metal ions that bind soil to fabric fibers
Stabilizing bleach
● — preventing metal-catalyzed decomposition of hydrogen peroxide and hypochlorite
Typical inclusion rates: 0.1% – 2.0% by weight in finished products.
Process | Role of Disodium EDTA |
Electroplating | Controls free metal ion concentration in plating baths for uniform deposition |
Electroless plating | Stabilizes nickel and copper baths by complexing excess metal ions |
Metal surface cleaning | Removes oxide layers and scale prior to coating, painting, or welding |
Etching & pickling | Assists in controlled metal dissolution for printed circuit board (PCB) manufacturing |
Scouring & bleaching
● : Removes metal ions from natural fibers (cotton, wool) to prevent discoloration and fiber damage during hydrogen peroxide bleaching
Dyeing
● : Sequesters hardness ions that would otherwise react with dyestuffs, ensuring level, reproducible color
Soaping-off
● : Improves removal of unfixed dye from fabrics, enhancing wash fastness
Disodium EDTA is used in color film developing as a component of bleach-fix (blix) solutions, where it complexes silver ions from the emulsion layer.
In pulp bleaching, EDTA chelates manganese and iron ions that catalyze the decomposition of hydrogen peroxide, improving bleaching efficiency and reducing chemical consumption.
Disodium EDTA is approved as food additive E386 (INS 386) in many jurisdictions, including under 21 CFR §172.135 in the United States. It functions as a preservative, sequestrant, and antioxidant synergist.
Food Category | Maximum Level (ppm) | Function |
Canned black-eyed peas | 145 | Promote color retention |
Canned cooked legumes (all types) | 165 | Promote color retention |
Canned vegetables (general) | Varies by type | Prevent discoloration from metal ions |
Canned seafood (e.g., shrimp, clams) | 250 | Prevent struvite crystal formation & discoloration |
Salad dressings, mayonnaise, sauces | 75 | Antioxidant synergist; preserve flavor & texture |
Canned carbonated soft drinks | 33 | Promote flavor retention |
Margarine | — | Protect flavor stability |
Processed fruits & vegetables | — | Prevent oxidative browning |
One of the fastest-growing uses of disodium EDTA is in the production of EDTA-chelated micronutrient fertilizers. EDTA is reacted with metal sulfates or oxides to produce stable, water-soluble chelates:
EDTA Chelate | Metal Content (typical %) | Primary Use |
EDTA-Fe (Iron) | 13% Fe | Correction of iron chlorosis in alkaline soils |
EDTA-Zn (Zinc) | 15% Zn | Prevention of zinc deficiency in corn, rice, wheat |
EDTA-Mn (Manganese) | 13% Mn | Correction of manganese deficiency in soybeans, cereals |
EDTA-Cu (Copper) | 15% Cu | Copper supplementation for cereals and vegetable crops |
EDTA-Mg (Magnesium) | 6% Mg | Magnesium supplementation in horticulture |
Application methods:
Soil application
● : Broadcast or banded; effective up to pH 7.0
Foliar spray
● : Rapid uptake through leaf stomata; typical concentration 0.1% – 0.5% w/v
Fertigation
● : Injected through drip or sprinkler irrigation systems
Hydroponics
● : Maintains micronutrient availability in nutrient solutions
Disodium EDTA is used in soil washing and phytoextraction to mobilize heavy metals (Pb, Cd, Zn, Cu) from contaminated soils, enabling their removal or plant uptake.
Important environmental consideration: EDTA is poorly biodegradable. In agricultural runoff, it can mobilize heavy metals in waterways. This has driven research into biodegradable alternatives such as IDS (iminodisuccinate) and EDDS (ethylenediaminedisuccinate), though EDTA remains the most cost-effective option for most applications.
Disodium EDTA is listed in the ingredient declarations of thousands of cosmetic and personal care products, typically at concentrations of 0.05% – 0.2%:
Product Category | Function |
Shampoos & body washes | Prevents metal-ion-induced rancidity and viscosity drift |
Liquid soaps | Maintains clarity and prevents soap scum formation |
Skin creams & lotions | Protects unsaturated oils and fragrances from oxidation |
Sunscreens | Stabilizes UV filters against metal-catalyzed degradation |
Makeup & color cosmetics | Preserves color integrity and prevents texture changes |
Wipes & cleansing waters | Enhances preservative efficacy by weakening microbial cell walls (adjunct effect) |
Disodium EDTA dihydrate is commercially available in several grades:
Grade | Purity (min.) | Key Standards | Typical Applications |
Industrial / Technical Grade | ≥ 99.0% | Internal specification | Water treatment, cleaning products, metal processing |
Food Grade (FCC) | ≥ 99.0% | FCC, E386, 21 CFR 172.135 | Food & beverage preservation |
Cosmetic Grade | ≥ 99.0% | Internal specification; meets CIR guidelines | Personal care products |
Analytical / ACS Reagent Grade | ≥ 99.5% | ACS specification | Laboratory analysis, titration standards |
Agricultural Grade | ≥ 99.0% | Internal specification | Micronutrient chelate production |
Parameter | Specification |
Assay (as C₁₀H₁₄N₂Na₂O₈ · 2H₂O) | 99.0% – 101.0% |
pH (1% solution) | 4.0 – 5.5 |
Loss on drying | 8.7% – 11.1% |
Heavy metals (as Pb) | ≤ 10 ppm |
Lead (Pb) | ≤ 2 ppm |
Arsenic (As) | ≤ 3 ppm |
Iron (Fe) | ≤ 10 ppm |
Nitrilotriacetic acid (NTA) | ≤ 0.1% |
Chloride (Cl) | ≤ 0.01% |
Sulfate (SO₄) | ≤ 0.02% |
Disodium EDTA (EDTA-2Na) has a lower pH (~4.5 in 1% solution) and is used in slightly acidic to neutral applications — such as food preservation, cosmetics, and cleaning products. Tetrasodium EDTA (EDTA-4Na) has a higher pH (~11 in 1% solution) and is preferred for alkaline systems like heavy-duty industrial cleaners, metal treatment baths, and high-pH water treatment. The two forms can also be blended to achieve a target working pH.
No. EDTA acid (CAS 60-00-4) is the free acid form with four carboxylic acid groups and very low water solubility (~0.05 g/100 mL). Disodium EDTA (CAS 6381-92-6 for dihydrate) is the partially neutralized disodium salt with high water solubility (~10 g/100 mL). Disodium EDTA is the workhorse form for most aqueous applications.
Disodium EDTA (E386) acts as a chelating preservative rather than an antimicrobial agent. It binds trace metal ions (iron, copper) that catalyze oxidation reactions, thereby preventing rancidity, color fading, and off-flavor development. In canned seafood, it prevents the formation of struvite (magnesium ammonium phosphate) crystals. It is often used together with antioxidants like ascorbic acid or tocopherols for enhanced protection.
No. Disodium EDTA, like all synthetic aminopolycarboxylate chelating agents, is not permitted in certified organic agriculture under USDA NOP, EU Organic Regulation, or equivalent standards. It is exclusively used in conventional agriculture.
EDTA-chelated micronutrients remain soluble and plant-available at higher soil pH (up to ~7.0) compared to sulfate forms, which tend to precipitate as insoluble hydroxides or oxides in neutral-to-alkaline soils. Foliar-applied EDTA chelates also achieve faster uptake. However, EDTA chelates are more expensive per unit of metal than sulfate salts, making them more economical for deficiency correction than for routine broadacre application.
Disodium EDTA has poor biodegradability in standard OECD tests (typically < 15% degradation in 28 days). It is, however, gradually photodegraded in surface waters in the presence of sunlight and iron. In wastewater treatment plants, EDTA can be partially removed through adsorption onto activated sludge, but a significant fraction may pass through into receiving waters. This has prompted the development of more biodegradable alternatives such as EDDS, IDS, and GLDA (glutamic acid diacetic acid) for environmentally sensitive applications.
Under recommended storage conditions (cool, dry, sealed containers at 15–25°C), disodium EDTA dihydrate has a typical shelf life of 24 to 36 months. The product is hygroscopic, so exposure to humidity can cause caking. Beyond the shelf life, the material should be retested against specification before use. Always verify the Certificate of Analysis (CoA) from your supplier.
Standard packaging includes 25 kg multi-wall paper bags with PE liner, 25 kg fiber drums, and 500 kg or 1,000 kg supersacks (FIBC) for bulk orders. Smaller packaging (1 kg, 5 kg) is available for laboratory and specialty applications. Ensure inner liners are sealed after each use to prevent moisture ingress.
For readers interested in related chelating agents and EDTA derivatives, the following guides may be useful:
● Tetrasodium EDTA (EDTA-4Na) — for high-pH industrial applications
● Calcium Disodium EDTA (E385) — food-grade alternative with reduced calcium-binding effect
● EDTA Acid (CAS 60-00-4) — the free acid form for specialized synthesis
● DTPA (Diethylenetriaminepentaacetic acid) — stronger chelate for highly alkaline environments
● HEDTA (Hydroxyethylethylenediaminetriacetic acid) — chelating agent for iron in alkaline conditions
● EDDS (Ethylenediaminedisuccinic acid) — biodegradable EDTA alternative
● GLDA (Glutamic acid diacetic acid) — readily biodegradable green chelating agent
