Phosphonates & salts
1-Hydroxyethylidene-1,1-diphosphonic acid
CAS 2809-21-4
HEDP, 1-hydroxyethylidene-1,1-diphosphonic acid (CAS 2809-21-4), is used for scale control, chelation and cleaning formulations. The current manufacturer TDS covers liquid with at least 60.0% active acid and crystal powder with at least 98.0% HEDP monohydrate content. Earlier catalogue grades are retained below for separate reference. H2Q INC. handles sales inquiries, technical-document requests, quotations and contracts. Share your specification, quantity, packaging and destination so the appropriate product and order terms can be confirmed.
Routine liquid: ≥ 60.0% active acid · Routine powder: ≥ 98.0% as HEDP·H₂O
Source: Jiyuan Qingyuan HEDP liquid and powder TDS. Routine manufacturer TDS supplied to H2Q on 28 October 2026. The liquid and powder tables use different content bases. Earlier catalogue grades are retained separately below for comparison; their availability and specifications require confirmation.
Review each form or grade with its source. Earlier catalogue references are labeled separately.
Manufacturer routine liquid TDS supplied on 28 October 2026. Colour is stated without an APHA/Hazen test scale in this sheet.
| Parameter | Reference specification |
|---|---|
| Appearance | Clear, colorless to pale yellow liquid, free from foreign matter |
| Active acid | ≥ 60.0 % |
| Phosphorous acid as PO₃³⁻ | ≤ 1.5 % |
| Phosphoric acid as PO₄³⁻ | ≤ 0.4 % |
| Chloride as Cl⁻ | ≤ 100 ppm w/w |
| Sequestration value as CaCO₃At pH 11–12 | ≥ 500 mg/g product |
| pH1% solution | ≤ 2.0 |
| Density20°C | ≥ 1.440 g/cm³ |
| Iron as Fe | ≤ 15.0 ppm |
| ColourScale not stated in the supplied TDS | ≤ 20 |
The content limit is reported as HEDP monohydrate, HEDP·H₂O. It is not a 98% anhydrous active-acid limit. This routine sheet does not separately specify the older catalogue’s ≥ 90% active-acid limit.
| Parameter | Reference specification |
|---|---|
| Appearance | White crystal powder |
| Active content as HEDP·H₂OMonohydrate basis; not anhydrous active-acid content | ≥ 98.0 % |
| Phosphorous acid as PO₃³⁻ | ≤ 0.8 % |
| Phosphoric acid as PO₄³⁻ | ≤ 0.5 % |
| Chloride as Cl⁻ | ≤ 100 ppm w/w |
| Iron as Fe | ≤ 20.0 ppm |
| pH1% solution | ≤ 2.0 |
Earlier catalogue specification retained for comparison, not the current routine TDS or a confirmation of grade availability. Liquid acid reference specification.
Source: Earlier Jiyuan Qingyuan HEDP catalogue.
| Parameter | Reference specification |
|---|---|
| Appearance | Clear, colorless to pale yellow liquid, free from foreign matter |
| Active acid | 58.0–62.0 % |
| Phosphorous acid as PO₃³⁻ | ≤ 2.0 % |
| Phosphoric acid as PO₄³⁻ | ≤ 0.8 % |
| Chloride as Cl⁻ | ≤ 100 ppm w/w |
| Iron as Fe | ≤ 35.0 ppm |
| pH1% solution | ≤ 2.0 |
| Sequestration value as CaCO₃At pH 11–12 | ≥ 500 mg/g product |
| Density20°C | ≥ 1.440 g/cm³ |
| Color (APHA) | ≤ 80 |
Earlier catalogue specification retained for comparison, not the current routine TDS or a confirmation of grade availability. Active acid and HEDP monohydrate are different reporting bases. The reference table does not state powder density, color or sequestration limits.
Source: Earlier Jiyuan Qingyuan HEDP catalogue.
| Parameter | Reference specification |
|---|---|
| Appearance | White crystal powder |
| Active acid | ≥ 90.0 % |
| Active content as HEDP·H₂OMonohydrate basis; different from active-acid content | ≥ 98.0 % |
| Phosphorous acid as PO₃³⁻ | ≤ 2.5 % |
| Phosphoric acid as PO₄³⁻ | ≤ 0.8 % |
| Chloride as Cl⁻ | ≤ 100 ppm w/w |
| Iron as Fe | ≤ 35.0 ppm |
| pH1% solution | ≤ 2.0 |
Earlier catalogue specification retained for comparison, not the current routine TDS or a confirmation of grade availability. This reference grade adds an arsenic limit. It does not list the separate copper, cobalt, titanium or lead limits shown for the low-heavy-metal grade.
Source: Earlier Jiyuan Qingyuan HEDP catalogue.
| Parameter | Reference specification |
|---|---|
| Appearance | Clear, colorless to pale yellow liquid, free from foreign matter |
| Active acid | 58.0–62.0 % |
| Phosphorous acid as PO₃³⁻ | ≤ 2.0 % |
| Phosphoric acid as PO₄³⁻ | ≤ 0.8 % |
| Chloride as Cl⁻ | ≤ 100 ppm w/w |
| Iron as Fe | ≤ 35.0 ppm |
| pH1% solution | ≤ 2.0 |
| Sequestration value as CaCO₃At pH 11–12 | ≥ 400 mg/g product |
| Density20°C | ≥ 1.440 g/cm³ |
| Color (APHA) | ≤ 80 |
| Arsenic as As | ≤ 1.0 ppm |
Earlier catalogue specification retained for comparison, not the current routine TDS or a confirmation of grade availability. This reference grade lists individual copper, cobalt, titanium and lead limits. An arsenic limit is not stated in this column.
Source: Earlier Jiyuan Qingyuan HEDP catalogue.
| Parameter | Reference specification |
|---|---|
| Appearance | Clear, colorless to pale yellow liquid, free from foreign matter |
| Active acid | 58.0–62.0 % |
| Phosphorous acid as PO₃³⁻ | ≤ 2.0 % |
| Phosphoric acid as PO₄³⁻ | ≤ 0.8 % |
| Chloride as Cl⁻ | ≤ 100 ppm w/w |
| Iron as Fe | ≤ 35.0 ppm |
| pH1% solution | ≤ 2.0 |
| Sequestration value as CaCO₃At pH 11–12 | ≥ 400 mg/g product |
| Density20°C | ≥ 1.440 g/cm³ |
| Color (APHA) | ≤ 80 |
| Copper as Cu | ≤ 1.0 ppm |
| Cobalt as Co | ≤ 1.0 ppm |
| Titanium as Ti | ≤ 1.0 ppm |
| Lead as Pb | ≤ 10.0 ppm |
Options and storage information listed in the manufacturer reference.
12 months
Indoors in a shaded, dry place, as stated in the manufacturer reference.
Confirm the current grade, packaging, storage period and supply terms for your order.
Share impurity limits and the intended application so the appropriate grade can be reviewed.
Product identity and overview: Qingyuan official HEDP product page . Confirm the current grade-specific documents for your application.
FOR U.S. PROCUREMENT TEAMS
Comparing HEDP supplier options? Start with the exact grade, your application and delivery requirements.
H2Q INC. handles U.S. sales, customer service, quotations and sales contracts. Jiyuan Qingyuan Water Treatment Co., Ltd., China, handles manufacturing, research and development, and export procedures. Tell H2Q your grade and destination so we can review the order requirements.
H2Q’s role and business contact · Manufacturer information and evidence
Specify the supplied form, exact grade, content reporting basis and impurity limits that your purchasing specification requires. State your trial quantity or recurring demand, with units. Minimum order quantity is confirmed individually for the grade, package and destination; there is no single minimum across this catalog.
Review HEDP specifications. The reference tables do not establish current availability or an accepted order quantity.
Give your required delivery date, destination city and state, ZIP code or receiving port, and preferred delivery terms. H2Q confirms lead time, packaging, transport arrangements and delivery terms for each order in the quotation and sales contract. Qingyuan handles export procedures; import responsibilities must be agreed for the destination.
Availability and delivery timing are confirmed for the specific order; this page does not indicate U.S. inventory.
The manufacturer lists these reference packaging options for HEDP:
Review HEDP packaging and storage. Ask for confirmation of the package, labeling and shipping arrangement for your grade and destination.
PLAN YOUR PRODUCT REVIEW
Compare the exact product and grade against your requirements before agreeing supply terms.
Also searched as: HEDP · Etidronic acid · EHDP
HEDP is used in scale and corrosion-control programs. Describe the deposits or corrosion issue, water hardness, alkalinity, operating pH and temperature, together with the current treatment chemistry.
For a chelating ingredient in a cleaning formulation, identify the required acid or salt form, target concentration and other ingredients. Include your compatibility tests and acceptance criteria when requesting a sample discussion.
For low-pressure boiler, oilfield-water or membrane-treatment inquiries, identify the system and feedwater conditions. Share the equipment materials and qualification requirements so the review can address that process.
Compare the current TDS coverage, chemical identities and content-reporting bases before preparing your purchasing specification. Document and grade differences do not establish interchangeable application performance.
Use the TDS for product review, the SDS for handling and regulatory review, and a relevant COA for batch-level checks.
Request HEDP documentsNo. This page identifies HEDP acid, CAS 2809-21-4. A sodium salt has a different chemical identity and neutralization level. If your formulation specifies a salt, provide its exact name and grade so the request can be reviewed without assuming interchangeability or availability.
The current liquid TDS specifies at least 60.0% active acid. The current powder TDS specifies at least 98.0% expressed as HEDP monohydrate, not 98% active acid. Earlier catalogue limits, including the separate 90% active-acid value and special liquid grades, remain labelled as prior references below; they do not add guarantees to the current routine TDS. State your form, reporting basis and impurity limits when requesting a grade.
Use the grade-specific TDS for technical parameters. Contact H2Q to obtain the SDS for your grade and destination, including during supplier qualification. Specify the tests you expect on the COA. A COA for a particular batch provides batch results; it does not replace application testing or establish the specification of every grade.
Include the chemical form, required specification, application, quantity, packaging preference, destination and target timing. Tell us whether you need documents, an evaluation-sample discussion or a commercial quotation so the response can address the next step in your purchasing process.
CONTINUE EXPLORING
Amino tri(methylene phosphonic acid)
2-Phosphonobutane-1,2,4-tricarboxylic acid
Disodium salt of diethylenetriamine penta(methylene phosphonic acid)