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    • HEDP (Etidronic Acid) CAS 2809-21-4

    HEDP (Etidronic Acid) CAS 2809-21-4

    HEDP (Etidronic Acid), also called 1-hydroxyethylidene-1,1-diphosphonic acid, CAS 2809-21-4, is an organophosphonic acid supplied for scale and corrosion control in industrial water treatment. Confirm the required concentration and grade, then request a quotation with COA/TDS/SDS for bulk supply.

    • CAS: 2809-21-4
    • Synonyms: HEDP; 1-Hydroxyethylidene-1,1-Diphosphonic Acid; Etidronic Acid
    • Einecs: 220-552-8
    • Molecular Formula: C2H8O7P2
    • Grade: Industrial grade / water treatment grade
    • Package: Standard export packaging
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    Product Description

    HEDP (Etidronic Acid) CAS 2809-21-4 is an organophosphonic acid with EINECS 220-552-8 and molecular formula C2H8O7P2.

    Synonyms: 1-Hydroxyethylidene-1,1-diphosphonic acid; Etidronic acid; HEDP.

    CAS: 2809-21-4.

    Molecular formula: C2H8O7P2.

    It is commonly supplied as a water-soluble liquid solution or higher-purity solid.

    It is also called 1-hydroxyethylidene-1,1-diphosphonic acid or etidronic acid.

    It is mainly used as a scale inhibitor, corrosion inhibitor, and metal-ion chelating agent in industrial water treatment.

    Typical systems include circulating cooling water, boiler water, industrial cleaning, and detergent formulations where metal salt deposition must be controlled.

    HEDP contains phosphonic acid groups that can sequester metal ions and adsorb onto surfaces.

    This helps prevent insoluble scale formation and reduce corrosion in hardness-containing water systems.

    Confirm active content or concentration, appearance, pH, density, phosphorus content or assay, chloride and iron content where relevant, and color.

    Liquid and solid grades differ in active content and handling, so the required supply form and concentration should be specified.

    Store in tightly closed original containers in a cool, dry, well-ventilated area away from direct sunlight, excessive heat, strong oxidizers, and incompatible materials.

    Use appropriate PPE and avoid skin or eye contact, especially when handling acidic liquid solutions.

    Confirm packaging suitable for the concentration, supply form, and order quantity, and follow the current SDS.

    Every batch is checked for active content or concentration, appearance, pH, density, phosphorus content or assay, chloride, iron, and color, with COA/TDS/SDS supplied per grade.

    Confirm active content, supply form, pH, packaging, and grade as required.

    The page is an RFQ entry point and does not state stock, price, MOQ, or fixed lead time.

    For an RFQ, state the intended application, required grade, quantity, packaging, destination, and document needs.

    FAQ - Technical & Supply Chain

    • Q:

      What is HEDP Diphosphonic Acid CAS 2809-21-4?

      A: HEDP Diphosphonic Acid is an organophosphonic acid with CAS 2809-21-4, EC 220-552-8, and molecular formula C2H8O7P2. It is also known as HEDP, etidronic acid, or 1-hydroxyethylidene-1,1-diphosphonic acid, and is commonly supplied as a water-soluble liquid solution or higher-purity solid.
    • Q:

      What is HEDP mainly used for?

      A: HEDP is mainly used as a scale inhibitor, corrosion inhibitor, and metal-ion chelating agent in industrial water treatment. Typical systems include circulating cooling water, boiler water, industrial cleaning, and detergent formulations where calcium, magnesium, iron, or other metal salt deposition must be controlled.
    • Q:

      Why does HEDP control scale and corrosion?

      A: HEDP contains phosphonic acid groups that can sequester metal ions and adsorb onto surfaces, helping to prevent insoluble scale formation and reduce corrosion. This makes it useful in hardness-containing water systems where inorganic deposits or metal contamination would otherwise reduce efficiency or damage equipment.
    • Q:

      What should be confirmed about the supplied grade?

      A: Confirm active content or concentration, appearance, pH, density, phosphorus content or assay, chloride and iron content where relevant, and color. Liquid and solid grades differ in active content and handling, so the required supply form and concentration should be specified for the target formulation.
    • Q:

      How should HEDP Diphosphonic Acid be stored and handled?

      A: Store it in tightly closed original containers in a cool, dry, well-ventilated area away from direct sunlight, excessive heat, strong oxidizers, and incompatible materials. Use appropriate PPE and avoid skin or eye contact, especially when handling acidic liquid solutions.

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