| HS Code | 891690 |
| Productname | Ethylenediamine Tetra-Acetic Acid (EDTA) |
| Abbreviation | EDTA |
| Iupacname | 2,2',2'',2'''-(ethane-1,2-diylbis(azanetriyl))tetraacetic acid |
| Casnumber | 60-00-4 |
| Ecnumber | 200-449-4 |
| Molecularformula | C10H16N2O8 |
| Molecularweight | 292.24 g/mol |
| Appearance | White crystalline powder |
| Odor | Odorless |
| Meltingpoint | 240 °C (decomposes) |
| Boilingpoint | Decomposes before boiling |
| Density | 0.86 g/cm³ |
| Solubilityinwater | Slightly soluble in water (approx. 0.5 g/L at 25 °C); soluble in alkaline solutions |
| Solubilityinorganicsolvents | Insoluble in common organic solvents |
| Ph | 2.5-3.5 (saturated aqueous solution) |
| Pka | 1.99, 2.67, 6.16, 10.26 |
| Logp | -3.86 (estimated) |
| Vaporpressure | Negligible at room temperature |
| Chelatingproperty | Strong chelating agent; forms stable 1:1 complexes with most metal ions |
| Stability | Stable under normal storage conditions; decomposes on strong heating |
| Storageconditions | Store in a cool, dry, well-ventilated area |
| Hazardclassification | Causes serious eye irritation; may cause respiratory irritation |
| Assay | ≥99.0% |
As an accredited Ethylenediamine Tetra-Acetic Acid (EDTA) factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Ethylenediamine Tetra-Acetic Acid (EDTA) is packaged in 25 kg polyethylene-lined fiber drums with secure lids and clear hazard labels. |
| Container Loading (20′ FCL) | Non-hazardous EDTA loaded in a 20′ FCL: palletized 25 kg bags/drums, stretch-wrapped, braced, and secured for safe ocean shipment. |
| Shipping | EDTA is generally shipped as a non-hazardous solid under the proper shipping name Ethylenediaminetetraacetic acid. It is packed in 25 kg bags, fiber drums, or supersacks, kept dry and away from oxidizers. Transport is not regulated under DOT/IATA/IMDG unless contaminated or in hazardous solutions. Store cool, dry, ventilated. |
| Storage | Store EDTA in a cool, dry, well-ventilated area, away from direct sunlight and moisture. Keep containers tightly closed, clearly labeled, and upright. Protect from dust and incompatible substances such as strong oxidizers, acids, and bases. Use secondary containment for solutions. Follow the safety data sheet and local regulations. |
| Shelf Life | EDTA solid is indefinitely stable when kept dry, sealed, and cool; aqueous solutions typically last months to years with proper storage. |
Trace Fe, Cu and Mn entering from raw water, caustic soda and stainless steel transfer lines control sodium hypochlorite residual in industrial and institutional cleaning formulations. Tetrasodium EDTA is incorporated at 0.05–0.5 wt% as active chelant in bleach-containing concentrates. The process sequence begins with demineralized water at 20–25 °C in a 5,000 L side-entry agitated 316L stainless vessel; tetrasodium EDTA is pre-dissolved to 0.2–0.5% and pH is adjusted to 7.0–9.0 with 32% sodium hydroxide before hypochlorite is dosed. Reverse order addition or direct contact of solid EDTA acid with sodium hypochlorite causes exothermic neutralization and chlorine off-gassing; this is an operational boundary. Viscosity of the finished concentrate is maintained at 300–800 mPa·s at 20 °C using spindle 3 at 20 rpm, and hypochlorite residual is checked after 14 days at 40 °C by iodometric titration according to ISO 7393-3. Sequestration capacity of disodium EDTA dihydrate is 269 mg CaCO3 per gram chelant; tetrasodium EDTA is preferred in liquid products because it dissolves without pH drop. Terminal products include institutional laundry destainers, hard-surface sanitising cleaners, automatic dishwashing gels and textile bleach boosters. Formulation compliance is assessed under Regulation (EC) No 648/2004 for detergent components, and effluent biodegradability of EDTA is low under OECD 301 series tests, which restricts dosage in European Ecolabel and Nordic Swan approved formulations.
In mechanical pulp processing, hydrogen peroxide is applied at 2–5% on oven-dry pulp after a chelation stage designed to remove transition metals. Screw-pressed and refined thermomechanical pulp is diluted to 3–5% consistency and treated with tetrasodium EDTA at 0.2–0.5 kg/t oven-dry pulp at pH 4.5–5.5 and 50–70 °C for 30–60 min. The treated pulp is then dewatered in a screw press before entering the bleach tower. Hydrogen peroxide alkaline charge is adjusted with sodium silicate and caustic soda to pH 10.0–10.8. Temperatures in the medium-consistency tower are held at 70–80 °C with a retention time of 60–120 min. The technical objective is to keep soluble Mn below the level where catalase-like decomposition shortens peroxide half-life; chelation efficiency is monitored by measuring peroxide residual at the tower outlet by iodometric titration, and pulp brightness is tested to ISO 2470-1 or TAPPI T 452. The terminal products are newsprint, supercalendered magazine paper, tissue grades and coated mechanical papers. Effluent limits are the operational boundary: EDTA itself is poorly retained in biological treatment and can remobilize heavy metals from sediment, so mills operating under EU Ecolabel for tissue or Nordic Swan criteria may replace part of the EDTA with biodegradable complexing agents at the wet end.
Continuous cotton preparation on a pad-steam range removes metal ions whose catalytic effect causes localised peroxide decomposition and can produce pinhole damage in bleached goods. A preparation formulation combines tetrasodium EDTA at 0.2–1.0 g/L with 20–40 mL/L hydrogen peroxide on 35% basis, sodium silicate or peroxide stabiliser, and caustic soda to pH 11.0–11.5. The fabric is impregnated at a padder nip pressure of 2–3 bar, then steamed at 100–102 °C for 15–20 min in a horizontal or loop steamer. Residual peroxide in the fabric before washing is checked by AATCC TM 102; target residual is normally 10–20% of the original bath to avoid premature cloth tendering. The chelant is not compatible with cellulase enzymes used in subsequent bio-polishing because Mg and Ca cofactors are stripped, so the fabric must be thoroughly washed at 85–90 °C before enzyme treatment. Terminal outputs include optically whitened cotton sheeting, knitted underwear, woven shirting and denim preparation for overdye. Downstream dyeing with acid, direct or reactive dyes benefits from lower metal content, and shade change after washing is assessed by ISO 105-C10:2006. Effluent discharge of EDTA from textile pretreatment is restricted in some supply chains; the specific configuration may require a chelation demand test before dosing is approved.
In recirculating cooling systems operating on hard groundwater, calcium carbonate scale develops on shell-and-tube heat exchangers, and this reduces overall heat transfer coefficient. Tetrasodium EDTA is fed as an online scale inhibitor at 5–30 mg/L active in the recirculating water, with the pH window of 7.5–9.0 maintained by sulfuric acid or caustic dosing. Alternatively, offline removal of existing calcium carbonate scale from plate-and-frame exchangers uses a 1–5 wt% solution of tetrasodium EDTA at pH 10–12 circulated at 40–60 °C for 6–24 h. The equipment train includes side-stream filtration at 10% of recirculating flow, passivation of carbon steel surfaces, and corrosion coupons evaluated according to NACE TM 0169. The terminal outputs are treated cooling water, steam generation feedwater after softening, and clean heat exchanger plates. The operational boundary is that EDTA is not compatible with oxidizing biocides such as chlorine or bromine at high concentration because the chelant can be oxidized; dosing of sodium hypochlorite and tetrasodium EDTA should be separated by at least 30–60 min or applied to different sections of the loop. For boiler feedwater, tetrasodium EDTA may be used in all-volatile treatment programmes at 1–5 mg/L, but only after deaeration; oxygen scavenger and amine pH-conditioning interactions are checked by ISO 5814 dissolved-oxygen measurement.
For greenhouse vegetables and ornamentals grown in recirculating hydroponic systems, inorganic ferrous sulphate is oxidised rapidly in aerated nutrient solution, whereas Fe-EDTA remains soluble within a defined pH window. Fe-EDTA containing 13% Fe is diluted to 1–5 mg Fe/L in the final nutrient solution, either by continuous injection at 1:100 from a concentrated stock tank or by direct addition after the calcium nitrate stock has been fully dispersed. Stock tanks are separated into an acidic micronutrient tank at pH 5.5–6.5 and a calcium/magnesium tank at pH 5.0–6.0 to avoid calcium phosphate and iron hydroxide precipitation. The pH of Fe-EDTA solutions must not exceed 6.5 for foliar or hydroponic use; above pH 7.0 the chelate is displaced and Fe(III) precipitates. Fertigation equipment includes venturi injectors or positive-displacement diaphragm pumps, pH and EC probes with 1–3 min feedback intervals, and batch mixing vessels from 500–2,000 L. Terminal crops include greenhouse tomato, lettuce, cucumber, citrus nursery stock and pot ornamentals. Compliance is assessed under Regulation (EU) 2019/1009 for micronutrient fertilisers, and the chelation efficiency of the product must meet the minimum declared value. In calcareous soils with pH above 7.5, Fe-EDDHA is used instead of Fe-EDTA because of the stability limitation. Published data for this specific configuration is limited for field-grown tree crops under rain-fed conditions, so dosing is established by leaf analysis rather than a single rate.
Alkaline electroless copper deposition for through-hole metallisation is operated with tetrasodium EDTA as the primary Cu(II) complexant in horizontal or vertical printed circuit board lines. The bath contains copper sulphate pentahydrate at 10–15 g/L, tetrasodium EDTA at 20–60 g/L, sodium hydroxide at 20–30 g/L, and formaldehyde at 5–10 mL/L. pH is maintained at 12.4–12.8 by automatic caustic addition, and the working temperature is controlled to 25–45 °C with PTFE-coated immersion heaters. Air sparging or eductor recirculation provides solution movement, while continuous filtration through 1 µm polypropylene cartridges removes copper fines that could trigger tank decomposition. The complexed Cu(II) concentration and free formaldehyde are determined by iodometric titration per IPC-TM-650 2.3.36, and plated thickness on glass-epoxy coupons is checked by cross-section according to IPC-6012. The terminal product is a printed circuit board with 0.3–1.0 µm electroless copper in drilled vias before electrolytic copper build-up. An operational boundary is the Cannizzaro side reaction of formaldehyde at high pH; it consumes sodium hydroxide and raises formate levels, so replenishment is based on acid titration and specific gravity rather than fixed time. This bath is not compatible with excessive air flow, which oxidises formaldehyde and shifts pH, and copper overboard at the rinse must be treated to meet PCB wastewater discharge limits.
When calcium sulphate, iron carbonate and hydrogen sulphide coexist in a production tubing scale deposit, tetrasodium EDTA solutions are used rather than uninhibited hydrochloric acid. A treatment string is run on coiled tubing; a 5–20 wt% solution of tetrasodium EDTA in fresh water is prepared at pH 10–12, heated only by wellbore temperature, and pumped at 0.5–2 bbl/min. The chelant dissociates calcium carbonate by complexing Ca(II), and the resultant calcium-EDTA species remains soluble at pH above 10; Fe(III) is held in solution as Fe(III)-EDTA, preventing ferric hydroxide precipitation during cleanout. Soak time is usually 6–24 h depending on bottomhole temperature, with upper application temperature limited to 150 °C because thermal degradation of the chelant accelerates above this level. Post-job returns are sampled and analysed for Ca, Mg and Fe by inductively coupled plasma optical emission spectrometry according to ISO 11885:2009; spent chelant is neutralised before disposal. Terminal products are restored wellbore cleanout, recovered production from scale-plugged zones, and protected downhole metallurgy compared with uninhibited acid treatments. The operational boundary is the incompatibility of concentrated EDTA with high-calcium brines: if the mixing water already contains more than 5,000 mg/L Ca, the free chelant demand is partially consumed before it reaches the scale face, so a pre-flush with fresh water is needed.
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Ethylenediamine tetraacetic acid (EDTA), CAS 60-00-4, is an aminopolycarboxylic acid with the molecular formula C10H16N2O8 and molecular weight 292.24 g/mol. The IUPAC designation is 2,2′,2″,2‴-(ethane-1,2-diyldinitrilo)tetraacetic acid. Industrial distribution covers the free acid, disodium salt dihydrate (CAS 6381-92-6), tetrasodium salt tetrahydrate (CAS 13235-36-4), and calcium disodium salt used as food additive E385. The free acid exhibits water solubility of approximately 0.5 g/L at 25 °C; the disodium dihydrate dissolves at greater than 100 g/L at 20 °C. Stepwise acid dissociation constants are approximately pKa1 2.0, pKa2 2.7, pKa3 6.2, and pKa4 10.3. With two amine nitrogen and four carboxylate oxygen donor atoms, the molecule binds one metal ion per ligand, giving a calculated chelation value of 342.5 mg CaCO3/g for the free acid.
In cooling water treatment, disodium EDTA dihydrate behaves as a stoichiometric chelant rather than a threshold scale inhibitor. The dose is tied to the molar metal load: 372.24 g of disodium EDTA dihydrate complexes 1 mol of Ca²⁺, Cu²⁺, or Fe³⁺. At 25 °C and 0.1 M ionic strength, the Fe(III)-EDTA stability constant is approximately 25.1, whereas the Ca(II)-EDTA value is approximately 10.7; dissolved iron is therefore complexed preferentially over hardness. Supplier technical guidance for iron-fouled cooling water commonly places maintenance doses in the 2–15 mg/L active acid range when iron remains below 1.0 mg/L. The chelant does not provide particulate dispersion; a polymeric dispersant is still required when suspended solids exceed 15 mg/L. Filtered samples for uncomplexed metal should be passed through a 0.45 µm membrane and analyzed by ICP-OES per ISO 11885 to verify that the stoichiometric reserve is not exceeded.
Disodium EDTA dihydrate in 1% aqueous solution has a pH of 4.0–5.0 and is selected for near-neutral cleaning formulations, personal care, and pharmaceutical assays. Tetrasodium EDTA tetrahydrate has a 1% solution pH of 10.5–11.5 and is used where alkaline pH is advantageous, such as photographic developing baths, alkaline derusting, and bottle washing. The sodium content of the disodium dihydrate is approximately 12.4% by mass; for the tetrasodium tetrahydrate it is approximately 20.3%. Calcium disodium EDTA, used as E385 in food, supplies calcium and exchanges weaker Ca²⁺ for trace Fe³⁺ and Cu²⁺ in food matrices; it is regulated under FDA 21 CFR 172.120 and EU Regulation 231/2012. Selection of the salt form is therefore based on pH, sodium contribution, and regulatory end use.
| Form | CAS | Formula | Molecular weight | pH (1%, 25 °C) | Water solubility | Chelation value (calculated) |
|---|---|---|---|---|---|---|
| Free acid | 60-00-4 | C10H16N2O8 | 292.24 g/mol | 2.2–3.0 (saturated solution) | 0.5 g/L at 25 °C | 342.5 mg CaCO3/g |
| Disodium dihydrate | 6381-92-6 | C10H14N2Na2O8·2H2O | 372.24 g/mol | 4.0–5.0 | >100 g/L at 20 °C | 268.9 mg CaCO3/g |
| Tetrasodium tetrahydrate | 13235-36-4 | C10H12N2Na4O8·4H2O | 452.23 g/mol | 10.5–11.5 | >100 g/L at 20 °C | 221.4 mg CaCO3/g |
Commercial disodium EDTA dihydrate is typically controlled to 99.0–101.0% assay on the anhydrous basis. Producer certificates of analysis commonly report nitrilotriacetic acid below 0.1%, chloride below 0.01%, sulfate below 0.05%, and water content in the range of 9.0–10.0% for the dihydrate form. The theoretical water content of the dihydrate is 9.68%. Pharmaceutical Edetate Disodium is controlled under the relevant USP-NF monograph, and elemental impurity testing follows USP <232> and USP <233> where the monograph requires. Food-grade calcium disodium EDTA must comply with FDA 21 CFR 172.120 and EU Regulation 231/2012 as E385. Reagent water for laboratory evaluation is prepared to ASTM D1193 Type II. Chelation values are calculated from molecular weight and can be checked by calcium titration with 0.1 mol/L CaCl₂, followed by membrane filtration and ICP-OES per ISO 11885 where confirmatory trace-metal data are required.
EDTA is also the standard titrant in water hardness determination. Under ISO 6059:1984, a sample buffered to pH 10.0–10.1 is titrated with 0.01 mol/L Na₂EDTA using Eriochrome Black T or Calmagite indicator; 1 mL of 0.01 mol/L EDTA corresponds to 1.00 mg CaCO₃. This analytical use depends on the 1:1 metal-ligand stoichiometry and is independent of the product form after conversion to active acid equivalent.
In mechanical pulp hydrogen peroxide bleaching, transition metals are first removed by chelant washing. Disodium EDTA dihydrate is applied at 0.2–0.5% on oven-dry pulp in a stirred stock chest at 50–70 °C and pH 5.0–6.0 for 30–60 min. The wash removes loosely bound Fe³⁺ and Mn²⁺; after pressing, the pulp enters the peroxide stage at typical charges of 20–30 kg/t H₂O₂ and pH 10.5–11.0. Under the alkaline peroxide condition, DTPA or magnesium sulfate stabilization becomes the primary stabilization mechanism because the Fe(III)-DTPA complex has a higher stability constant than Fe(III)-EDTA. Published data for EDTA as the sole alkaline peroxide stabilizer above pH 11.0 is limited; mill practice commonly confines EDTA to the acid pre-wash.
For reactive dyeing of cotton, disodium EDTA dihydrate is added at 0.5–2.0 g/L when supply water hardness exceeds 50 mg/L CaCO₃. The chelant prevents calcium and magnesium from forming insoluble carbonates and from interfering with vinyl sulfone or monochlorotriazine dye fixation. Dye exhaustion is followed by UV-Vis absorbance at the dye λmax; wash fastness is tested according to ISO 105-C06. Overdosage above 3.0 g/L may draw Cu²⁺ from copper-complex direct or reactive dyes and alter tone; this is an operational boundary for turquoise and navy formulations.
In bottle-washing lines, tetrasodium EDTA is used at 1–5 g/L in NaOH solutions of 2–3% at 80 °C to sequester hardness and prevent scale accumulation on spray nozzles and tunnel metal surfaces. The product is selected when the cleaner must retain high pH and when phosphate restrictions require non-phosphate scale control. Scale performance is monitored by pressure drop across nozzles and by coupon weight change; published comparative data for this specific configuration is limited, so line trial data govern the final dose.
Relative to diethylenetriaminepentaacetic acid (DTPA), EDTA has a lower Fe(III) stability constant—25.1 versus approximately 28.6—and is less suitable for alkaline peroxide stabilization. DTPA is selected in mechanical pulp bleach plants where the pH exceeds 10.5 and peroxide residuals remain above 0.5 g/L. Nitrilotriacetic acid is a tetradentate chelant with lower metal stability constants and a more restrictive toxicological classification in some jurisdictions; it is limited to closed industrial applications. Phosphonates such as HEDP and ATMP are threshold scale inhibitors that act at substoichiometric doses of 5–15 mg/L and survive chlorine residuals; EDTA is stoichiometric and is degraded by strong oxidizers. Citric acid and sodium gluconate are readily biodegradable but have substantially lower Fe(III) stability constants; citric acid has a Fe(III) log K of approximately 11.9, making it unsuitable for iron control in hydrogen peroxide systems. Readily biodegradable chelants such as L-glutamic acid diacetic acid and methylglycinediacetic acid offer improved environmental profiles relative to EDTA, which is not classified as readily biodegradable under OECD 301 test conditions and may persist in conventional activated sludge. This environmental boundary drives substitution in cleaning formulations where wastewater treatment plant removal efficiency is a permit condition.
In hydroponic nutrient solutions, Fe-EDTA is a soluble iron source for crops grown in the pH range 5.5–6.5. Above pH 6.5, bicarbonate competes for iron and Fe-EDDHA or Fe-DTPA is preferred because EDTA loses Fe solubility. A typical recirculating nutrient film technique program uses 2–3 mg/L Fe from Fe-EDTA; filtered nutrient solution iron is verified by 0.45 µm membrane filtration and ISO 11885 ICP-OES.
Operational constraints require attention to pH and oxidation potential. Free acid EDTA should not be dry-blended into high-pH liquid concentrates without prior neutralization because solubility below pH 2.0 is poor. Tetrasodium EDTA solutions should not be stored in aluminum tanks at pH above 10.0 because alkaline attack can generate hydrogen and damage the vessel. In chlorinated process waters, EDTA demand increases because hypochlorous acid degrades the chelant; systems with continuous chlorination and free chlorine residuals above 0.5 mg/L may require frequent monitoring and supplemental feed. Published data for EDTA performance in superheated boiler water above 6.9 MPa is limited, and polymer-phosphate or all-polymer programs are more common in that operating envelope.
