HEDP.4NA

HEDP.4NA is the common trade abbreviation for tetrasodium etidronate, the fully neutralised sodium salt of 1-hydroxyethane-1,1-diphosphonic acid (CAS No 3794-83-0, C2H4Na4O7P2), supplied as a clear alkaline solution of about 30 %, as a powder or as dust-free granules, and used as a sequestrant, peroxide stabiliser, water softener and scale inhibitor in detergents, I&I cleaners, textile processing, soaps and personal care, electroplating and water treatment.
Tetrasodium etidronate (HEDP.4NA) is chosen by formulators of alkaline and solid products because it delivers the strong metal-binding and anti-scaling performance of HEDP without adding acidity, it can be tableted and blended into powders in its granular form, and it remains stable to hydrolysis, heat and, to a good extent, chlorine and peroxide.
Tetrasodium HEDP (HEDP.4NA) acts in two ways: at low dosages it inhibits the precipitation of calcium carbonate by adsorbing on growing crystals (threshold effect), and at higher dosages it binds calcium, magnesium and especially catalytically active iron, copper and manganese ions in stable complexes, which softens water and prevents these metals from decomposing hydrogen peroxide or discolouring products.

CAS No: 3794-83-0
EC No: 223-267-7
Molecular formula: C2H4Na4O7P2
Molecular weight: 293.96 g/mol
INCI name: Tetrasodium Etidronate
Solution grade: approx. 30 % HEDP.4NA, pH 10–12, density 1.26–1.36 g/cm³
Solid grade: min. 80–85 % HEDP.4NA, pH (1 %) 11–12

COMMON PRODUCT & CHEMICAL NAMES OF HEDP.4NA:

HEDP.4NA, HEDP.4Na, HEDP 4Na, HEDP-4Na, HEDP.Na4, HEDP Na4, HEDP·Na4, HEDP•Na4, Tetrasodium Etidronate, Etidronate Tetrasodium, Etidronic Acid Tetrasodium Salt, Tetrasodium HEDP, HEDP Tetrasodium, HEDP Tetra Sodium Salt, 1-Hydroxyethylidene-1,1-Diphosphonic Acid Tetrasodium Salt, 1-Hydroxyethane-1,1-Diphosphonic Acid Tetrasodium Salt, (1-Hydroxyethylidene)bis-phosphonic Acid Tetrasodium Salt, Tetrasodium (1-Hydroxyethylidene) Bisphosphonate, Sodium (1-Hydroxyethane-1,1-diyl)bis(phosphonate), HEDP.4Na Liquid, HEDP.4Na Powder, HEDP.4Na Granules, Dequest 2016, Dequest 2016D, Turpinal 4NL

The fully neutralised phosphonate (HEDP.4NA) is simply another way of writing HEDP•Na4: the "4NA" or "Na4" part indicates four sodium ions per molecule of HEDP (etidronic acid). The INCI name used in cosmetic ingredient lists is Tetrasodium Etidronate. In technical documents, the product may also be called "HEDP tetrasodium" or "tetrasodium HEDP". Dequest 2016 (solution), Dequest 2016D (powder) and Turpinal 4NL are examples of commercial tetrasodium HEDP products.
When ordering, HEDP.4NA should not be confused with HEDP 60 % (the acid, CAS 2809-21-4), HEDP.2NA or HEDP.Na2 (the disodium salt, CAS 7414-83-7), HEDP.K4 (tetrapotassium salt) or "HEDP sodium salt" products with undefined neutralisation (CAS 29329-71-3). These products contain the same phosphonate anion but differ in pH, active content and solubility behaviour.

WHAT IS HEDP.4NA?

The fully neutralised phosphonate (HEDP.4NA) is the sodium salt of an organophosphonic acid. Its parent, HEDP or etidronic acid (CH3C(OH)(PO3H2)2), has two phosphonic acid groups on the same carbon atom and a hydroxyl group next to them. Each phosphonic acid group can release two protons. Tetrasodium etidronate (HEDP.4NA) is the form in which four of these acidic protons have been neutralised with sodium hydroxide, giving the tetra-anion CH3C(OH)(PO3)2 4- with four Na+ counter-ions.
Commercial HEDP.4NA is produced by neutralising HEDP acid with sodium hydroxide. The resulting solution is adjusted to about 30 % HEDP.4NA (approx. 21 % as HEDP acid), or spray-dried and, if required, granulated to obtain a powder of about 80–85 % HEDP.4NA with residual moisture. Granular grades are designed to be free-flowing and low in dust.

Many cleaning and processing formulations are alkaline: laundry detergents, dishwashing products, bottle washing, metal degreasers, peroxide bleaching baths for cotton. In these systems, hardness ions and trace metals cause problems such as limescale, greying, spotting, metal-catalysed decomposition of hydrogen peroxide and discolouration. Tetrasodium etidronate (HEDP.4NA) is designed to solve these problems in alkaline conditions.
Because HEDP.4NA is already fully neutralised, formulators do not need to add extra caustic soda to neutralise the phosphonate, and the product does not cause a pH drop when added. In powders and tablets the solid or granular form of HEDP.4NA can be dry-mixed with builders, percarbonate, surfactants and enzymes.

Tetrasodium HEDP (HEDP.4NA) is also widely used in water treatment for cooling and boiler water, oilfield water and swimming pools, where it prevents calcium carbonate scale and helps control corrosion. Its phosphorus–carbon–phosphorus backbone is stable at high temperatures and extreme pH, and it does not hydrolyse to orthophosphate like inorganic polyphosphates.

HEDP.4NA in everyday and industrial products: laundry powders, liquids and tablets, automatic and manual dishwashing products, hard surface and bathroom cleaners, I&I kitchen and laundry products, bottle washing and CIP additives, metal cleaners, cotton and blend bleaching, dye baths, bar soaps, shampoos and hair colour developers, cyanide-free electroplating baths, cooling towers, boilers, pools.

CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION OF HEDP.4NA

Product name: HEDP.4NA
INCI name: Tetrasodium Etidronate
Chemical name: Tetrasodium (1-hydroxyethylidene)bisphosphonate
CAS No: 3794-83-0
EC / EINECS No: 223-267-7
Molecular formula: C2H4Na4O7P2
Molecular weight: 293.96 g/mol
InChIKey: KWXLCDNSEHTOCB-UHFFFAOYSA-J
Acid form (for active calculation): HEDP, C2H8O7P2, 206.03 g/mol
Conversion: 1 kg HEDP.4NA corresponds to approx. 0.70 kg HEDP acid
Chemical class: Organophosphonate salt
Main functions: Sequestrant, chelating agent, peroxide stabiliser, water softener, scale and corrosion inhibitor, deflocculant

GRADES AND SPECIFICATIONS OF HEDP.4NA

Tetrasodium HEDP (HEDP.4NA) is offered in three typical forms. The values below are typical specifications from producers, they are not a guarantee for every grade.

HEDP.4NA LIQUID
Appearance: Colourless to yellowish transparent liquid
HEDP.4NA content: 29.0–31.0 %
Active as HEDP: 20.3–21.7 %
Total phosphate (as PO4 3-): 18.4–20.4 %
Density (20 °C): 1.26–1.36 g/cm³
pH: 10.0–12.0
Iron (Fe): max. 20 mg/L
Typical use: liquid detergents and cleaners, water treatment blends, textile auxiliaries

HEDP.4NA POWDER, STANDARD
Appearance: White powder
HEDP.4NA content: min. 80.0 %
Active as HEDP: min. 56.0 %
Moisture: max. 15.0 %
pH (1 % solution): 11.0–12.0
Iron (Fe): max. 35 mg/L
Typical use: powder blends, solid water treatment products

HEDP.4NA POWDER OR GRANULES, HIGH GRADE
HEDP.4NA content: min. 85.0 %
Active as HEDP: min. 58.0 %
Moisture: max. 10.0 %
pH (1 % solution): 11.0–12.0
Iron (Fe): max. 35 mg/L
Typical use: detergent powders and tablets, dust-free dry blending

GENERAL PROPERTIES OF HEDP.4NA:
Solubility: Freely soluble in water
Hygroscopicity: Powder is hygroscopic and can deliquesce in moist air, keep packaging closed
Stability: Hydrolytically and thermally stable, good stability towards chlorine and peroxide compared with many other sequestrants

The specification of each HEDP.4NA grade supplied is available on request from Ataman Kimya.

HEDP.4NA IN DETERGENTS AND I&I CLEANERS

In laundry detergents, HEDP.4NA sequesters calcium and magnesium, prevents carbonate deposits on fabrics and machine parts (incrustation and greying) and, very importantly, binds iron, copper and manganese, which would otherwise catalyse the decomposition of percarbonate or perborate bleach and could damage fibres. The fully neutralised phosphonate (HEDP.4NA) therefore improves bleach efficiency and colour care.
In automatic dishwashing and rinse aids, HEDP.4NA reduces spotting and filming on glass, especially in hard water. In bottle washing and CIP cleaning with caustic soda, HEDP.4NA prevents scale and keeps equipment clean. In metal cleaners it helps remove and keep metal oxides and hardness salts in solution.
The granular form of HEDP.4NA is free-flowing, low in dust and can be tableted, which makes it suitable for tablets and compact powders.

Note on phosphorus: HEDP.4NA contains phosphorus. In the EU, consumer laundry and automatic dishwasher detergents are subject to limits on total phosphorus content per dose, which also include phosphonates. Formulators should calculate the phosphorus contribution of HEDP.4NA.

HEDP.4NA IN TEXTILE, SOAP, COSMETIC AND PLATING APPLICATIONS

Textile pretreatment and dyeing: in alkaline peroxide bleaching of cotton and blends, HEDP.4NA stabilises hydrogen peroxide, prevents catalytic damage (pinholes) caused by iron and copper, and helps achieve uniform whiteness. In dye baths, HEDP.4NA sequesters hardness and metal ions that can change shades, and it is used as an auxiliary for dye fixing.
Soaps: in bar and liquid soaps, HEDP.4NA (Tetrasodium Etidronate) binds trace metals that accelerate oxidation, so it reduces rancidity, discolouration and odour changes.
Cosmetics and hair colour: in shampoos, shower gels and hair products, Tetrasodium Etidronate is a chelating agent. In hair colour developers and bleaching products containing hydrogen peroxide, it stabilises the peroxide, preventing loss of activity and the build-up of oxygen gas that can make packages swell. In the EU, etidronic acid and its salts are listed with use restrictions in the Cosmetics Regulation (for example for hair care and soap, with maximum concentrations expressed as etidronic acid), the current limits must be checked before use.
Electroplating: in cyanide-free copper and other plating baths, HEDP.4NA acts as a complexing agent for metal ions.

HEDP.4NA IN WATER TREATMENT

Tetrasodium etidronate (HEDP.4NA) is an established inhibitor for calcium carbonate scale in circulating cooling water, low- and medium-pressure boilers, oilfield water injection and pipelines, and swimming pools. Low mg/L dosages are typically enough because of the threshold effect. Tetrasodium HEDP (HEDP.4NA) also forms stable complexes with iron, copper and zinc, so it reduces staining and supports zinc-based corrosion inhibition. Manufacturers state that HEDP-based products keep their scale and corrosion inhibiting effect at temperatures up to about 250 °C. For heavily sulphate- or silica-loaded waters, HEDP.4NA is usually combined with other phosphonates or polymers.

WHICH PROBLEMS DOES HEDP.4NA SOLVE?

- Bleach loses activity in detergent powders or bleaching baths → HEDP.4NA binds the metal ions that decompose peroxide.
- White laundry turns grey and machines scale up → HEDP.4NA prevents calcium carbonate deposition.
- Glasses show spots after dishwashing → HEDP.4NA sequesters hardness and controls film formation.
- Soap bars change colour or develop off-odour → HEDP.4NA chelates pro-oxidant metals.
- Hair colour developer bottles swell → HEDP.4NA stabilises hydrogen peroxide.
- Acid HEDP cannot be used in a powder or alkaline liquid → HEDP.4NA is neutralised and available as solid granules.
- Scale in cooling water and boilers → HEDP.4NA inhibits carbonate scale at low dosage.

THINGS TO CONSIDER WHEN USING HEDP.4NA

- Compare on active basis: 30 % liquid and 85 % granules contain very different amounts of active HEDP, calculate dosage as HEDP acid or as HEDP.4NA consistently.
- Alkalinity: HEDP.4NA adds alkalinity to a formula, take this into account in pH adjustment.
- Calcium phosphonate precipitation: in very hard water with high pH and high HEDP.4NA dosages, insoluble calcium salts can form, use dispersant polymers where needed.
- Moisture: keep powders and granules sealed, caking reduces flow and dosing accuracy.
- Phosphorus: observe phosphorus limits in detergents and discharge permits.
- Environment: phosphonates are not readily biodegradable but are removed largely by adsorption in wastewater treatment.
- Cosmetic limits: follow the current regulatory limits for etidronic acid and its salts.

INITIAL FORMULATION APPROACHES WITH HEDP.4NA

The compositions below are illustrative starting mixtures (% w/w of the total mixture), not validated commercial recipes. Each totals 100 %. Percentages refer to the raw materials as supplied, confirm their active contents, compatibility and suitability for the intended use.

1. COMPACT LAUNDRY POWDER WITH OXYGEN BLEACH
Dry-blend HEDP.4NA granules at about 0.3–1 % (as supplied) with sodium carbonate, a zeolite or silicate builder, sodium percarbonate, a bleach activator, surfactant granules and enzymes. Test bleach stability during storage and washing performance in hard water.

Illustrative initial components (% w/w):
Sodium carbonate: 30 %
Zeolite builder: 20 %
Sodium silicate: 5 %
Sodium percarbonate: 15 %
Bleach activator (for example TAED): 3 %
Surfactant granules: 15 %
HEDP.4NA granules: 0.5 %
Enzyme granules: 0.5 %
Sodium sulphate: 11 %
Total: 100 %

2. ALKALINE PEROXIDE BLEACHING OF COTTON
Prepare a bath with water, sodium hydroxide, hydrogen peroxide, a wetting agent and HEDP.4NA liquid at about 0.5–2 g/L, depending on water hardness and the metal content of the fabric. Monitor residual peroxide and whiteness and adjust the HEDP.4NA dosage.

Illustrative initial bath components (% w/w):
Water: 95.8 %
Sodium hydroxide solution (50 %): 1 %
Hydrogen peroxide solution (35 %): 3 %
Wetting agent: 0.1 %
HEDP.4NA solution (30 %): 0.1 %
Total: 100 %
The HEDP.4NA solution level here is 1 g/kg of bath, conversion to the g/L range above requires the actual bath density. This composition is not a mixing-order instruction.

3. MILD BAR SOAP WITH CHELATING PROTECTION
Add HEDP.4NA (as Tetrasodium Etidronate) to the soap base at a low level within the regulatory limit for soap, together with an antioxidant, and evaluate colour and odour stability during accelerated ageing.

Illustrative initial components (% w/w):
Soap base: 99.93 %
HEDP.4NA solution (30 %): 0.05 %
Antioxidant: 0.02 %
Total: 100 %
This HEDP.4NA solution level supplies 0.015 % tetrasodium salt, equivalent to approximately 0.0105 % HEDP acid. Confirm the applicable cosmetic limits and antioxidant suitability before selecting the final levels.

These levels are only starting points. Each formulation must be tested and adjusted to the raw materials, water quality and regulations.

ALTERNATIVES TO HEDP.4NA

HEDP acid: same phosphonate, acidic, for acidic cleaners and descalers.
HEDP.2NA: partially neutralised salt for near-neutral formulations.
DTPMP sodium salts: stronger peroxide stabilisation and sulphate scale control in textile bleaching and detergents.
ATMP sodium salts and PBTC: alternative phosphonates for water treatment.
EDTA, DTPA: aminocarboxylate chelating agents with high stoichiometric binding capacity.
MGDA and GLDA: readily biodegradable chelating agents for phosphorus-free formulations.
Sodium citrate and gluconate: mild, biodegradable sequestrants with lower performance.
Polycarboxylates and polyaspartates: dispersants and anti-incrustation polymers.

HOW DOES HEDP.4NA WORK AT THE MOLECULAR LEVEL?
 
HEDP.4Na is the tetrasodium salt of 1-hydroxyethylidene-1,1-diphosphonic acid, also known as tetrasodium etidronate. Its central carbon carries a methyl group, a hydroxyl group and two phosphonate groups, each joined to carbon through a direct C–P bond. In the tetrasodium form, four of the acidic P–OH protons are replaced by sodium, so the molecule dissolves readily in water as a multiply charged anion. Almost all of its functions come from how this compact cluster of phosphonate oxygens and a hydroxyl group interacts with metal ions and with crystal surfaces.
 
Chelation of metal ions: The oxygen atoms of the two phosphonate groups, together with the hydroxyl oxygen, can close around a metal ion and hold it in a stable ring structure. Tetrasodium etidronate binds calcium and magnesium as well as transition metals such as iron, copper, zinc and manganese. Once bound, these ions are kept in solution and are far less able to precipitate as scale, form soap scum or catalyse unwanted reactions.
 
Threshold scale inhibition: The diphosphonate also works at concentrations far below what would be needed to bind every hardness ion. When calcium carbonate, calcium sulphate or similar salts begin to precipitate, the molecule adsorbs onto the active growth sites of the newly forming crystal nuclei. This blocks further addition of ions at those points, slows crystal growth and distorts the crystal lattice. The resulting crystals stay small, irregular and loosely adherent, so they are less likely to build hard deposits on heat exchangers, pipes and membranes. This substoichiometric action is known as the threshold effect.
 
Dispersion and deposit control: Because adsorbed HEDP anions carry a high negative charge, they increase the surface charge of fine particles and crystallites. Electrostatic repulsion between the particles reduces agglomeration and keeps them suspended in the water phase, where they can be removed with the flow instead of settling.
 
Corrosion inhibition: On steel and other metal surfaces, the phosphonate interacts with metal ions at the surface and, often together with calcium or zinc in the water, forms a thin, poorly soluble protective film. This film limits contact between the metal and corrosive species. The effect is especially useful in cooling water treatment, where scale inhibition and corrosion control are needed at the same time.
 
Stabilisation of peroxide and bleaching systems: Traces of iron, copper and manganese catalyse the decomposition of hydrogen peroxide and other peroxygen bleaches into oxygen and water. By sequestering these metals, HEDP.4Na slows this decomposition, keeps more active oxygen available for bleaching and reduces damage to fibres in textile and pulp processes.
 
Hydrolytic stability: Unlike inorganic polyphosphates, which contain P–O–P bonds that hydrolyse to orthophosphate in hot or alkaline water, the diphosphonate is built on C–P bonds. These bonds resist hydrolysis across a wide pH and temperature range, so the molecule keeps its functionality in hot, alkaline cleaning and water treatment systems.
 
Alkaline character of the tetrasodium salt: In solution, the phosphonate groups of the tetrasodium salt can take up protons from water, giving an alkaline pH. This makes the product convenient in alkaline detergents and cleaners, and it can be blended with the acid form of HEDP to reach a desired pH.
 
Affinity for calcium phosphate surfaces: The same diphosphonate arrangement binds strongly to calcium phosphate surfaces such as hydroxyapatite. This explains the use of etidronate as a pharmaceutical active and also why phosphonates adsorb readily to mineral surfaces and sludge in the environment.
 
Use in cosmetics and soaps: In personal care products and soaps, tetrasodium etidronate binds metal ions from water and raw materials. This reduces soap scum in hard water, helps maintain foam and limits metal-catalysed oxidation that can lead to discolouration and rancid odours.
 
Its performance depends on water hardness, pH, temperature, metal ion content, the presence of oxidisers and the other components of the formulation. HEDP.4Na dosage and process conditions should therefore be confirmed through laboratory trials.

QUALITY CONTROL AND PURCHASING CRITERIA FOR HEDP.4NA

- confirm the salt form: tetrasodium (HEDP.4NA), not acid or disodium
- choose the form: 30 % liquid, standard powder or low-dust granules
- check HEDP.4NA content and active HEDP content
- iron, chloride and phosphate/phosphite impurities
- pH, density (liquid) or moisture and particle size (solid)
- for cosmetic use: cosmetic-grade documentation and INCI Tetrasodium Etidronate
- COA for each batch, TDS and SDS

Specifications, certificates and samples of HEDP.4NA are available on request from Ataman Kimya.

STORAGE AND HANDLING OF HEDP.4NA

Keep HEDP.4NA in the original closed packaging, in a dry, cool and well-ventilated place. The powder and granules are hygroscopic and must be protected from humidity. Protect the liquid from frost and long exposure to heat. Suitable materials are polyethylene, polypropylene and stainless steel, avoid long contact with aluminium, zinc and galvanised surfaces because of the alkaline pH. Shelf life information for the supplied HEDP.4NA grade is available on request from Ataman Kimya.

SAFETY OF HEDP.4NA

The fully neutralised phosphonate (HEDP.4NA) is alkaline and is commonly classified as causing eye irritation, some SDS also include acute oral toxicity (harmful if swallowed). It is generally not regulated as dangerous goods for transport. The classification can vary with concentration and form, the SDS of the supplied product is available on request from Ataman Kimya.
Personal protection: safety glasses or goggles, protective gloves and work clothing, dust mask when handling powders without local exhaust.
First aid: eye contact – rinse immediately with plenty of water and remove contact lenses, seek medical advice if irritation continues, skin contact – wash with water, inhalation of dust – fresh air, swallowing – rinse mouth, drink water and seek medical advice.
Environmental precautions: prevent large quantities from entering drains and surface water.

BUYING HEDP.4NA

Tetrasodium etidronate (HEDP.4NA) is supplied as a liquid in plastic drums and IBCs, and as powder or granules in lined bags and big bags. When ordering HEDP.4NA, please specify the form (liquid, powder or granules), the minimum active content, the intended application (detergent, textile, cosmetic, water treatment or plating), the required documents and the quantity. Packaging sizes and lead times for HEDP.4NA are available on request from Ataman Kimya.

SUPPLY OF HEDP.4NA FROM ATAMAN KIMYA

Ataman Kimya supplies HEDP.4NA in liquid, powder and granular forms for detergent, cleaning, textile, cosmetic, plating and water treatment applications. Ataman Kimya helps customers select the most suitable form and grade, and provides TDS, SDS and COA documents and logistics support. For prices and samples, please contact Ataman Kimya.

FREQUENTLY ASKED QUESTIONS ABOUT HEDP.4NA

IS HEDP.4NA THE SAME AS HEDP•NA4 OR HEDP NA4?
Yes. These are different spellings of tetrasodium etidronate, CAS 3794-83-0.

WHICH FORM OF HEDP.4NA IS BEST FOR DETERGENT POWDERS AND TABLETS?
The granular form, because it is free-flowing, low in dust and can be tableted.

HOW CAN I CONVERT HEDP.4NA CONTENT TO HEDP ACID?
Multiply the HEDP.4NA content by approximately 0.70 (206.03 / 293.96). For example, 30 % HEDP.4NA corresponds to about 21 % HEDP.

WHY IS HEDP.4NA USED IN HYDROGEN PEROXIDE PRODUCTS?
It binds iron, copper and manganese ions that catalyse peroxide decomposition, so peroxide stays active and packages do not swell.

IS HEDP.4NA PHOSPHATE-FREE?
No. It is a phosphonate and contains phosphorus, which counts towards phosphorus limits in detergents.

CAN HEDP.4NA BE USED IN ACIDIC CLEANERS?
For acidic products, HEDP acid is normally used, HEDP.4NA is intended for neutral to alkaline systems.

WHAT IS THE PH OF HEDP.4NA?
About 10–12 for the 30 % solution and about 11–12 for a 1 % solution of the solid.

HEDP.4NA – TECHNICAL SUMMARY

Product name: HEDP.4NA
Other names: Tetrasodium Etidronate, HEDP•Na4, HEDP Na4, HEDP Tetrasodium Salt
CAS No: 3794-83-0
EC No: 223-267-7
Molecular formula: C2H4Na4O7P2
Molecular weight: 293.96 g/mol
INCI name: Tetrasodium Etidronate
Forms: Liquid 29–31 %, powder min. 80 %, powder or granules min. 85 %
Active as HEDP: approx. 21 % (liquid), min. 56–58 % (solid)
pH: 10–12 (liquid), 11–12 (1 % solution of solid)
Main functions: Sequestrant, peroxide stabiliser, water softener, CaCO3 scale inhibitor, corrosion inhibitor
Main uses: Detergents and I&I cleaners, textile bleaching and dyeing, soaps and personal care, electroplating, water treatment
Storage: Dry and closed, solid is hygroscopic

HEDP.4NA can be sourced from ATAMAN KİMYA. For further information and supply inquiries about HEDP.4NA, please contact ATAMAN KİMYA.