HEDP - Hebei Longke|Corrosion Inhibition&Scale Prevention

CAS No. 2809-21-4 | Molecular Formula: C₂H₈O₇P₂ | Molecular Weight: 206.02

Introduction

1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP) is a critical organophosphoric acid compound widely utilized in industrial water treatment systems. Known for its exceptional ability to chelate metal ions and inhibit scale and corrosion, HEDP plays a pivotal role in maintaining the efficiency and longevity of industrial equipment. Developed by Hebei Longke Water Treatment Co., Ltd., a leading Chinese manufacturer of water treatment chemicals, HEDP is a cornerstone of modern industrial maintenance strategies.

Chemical Properties and Mechanism of Action

HEDP is a corrosion scale inhibitor that functions through chelation. It forms stable complexes with metal ions such as Fe³⁺, Cu²⁺, and Zn²⁺, effectively preventing the formation of oxide layers on metal surfaces. This chelation process not only dissolves existing oxidized materials but also creates a protective barrier against future corrosion. According to the National Institute of Standards and Technology (NIST), such chelating agents are essential for maintaining the integrity of metal systems under high-temperature and high-pH conditions.

The compound's structural formula (illustrated below) highlights its unique diphosphonic acid groups, which enhance its affinity for metal ions:

HEDP demonstrates remarkable chemical stability, resisting hydrolysis and decomposition under normal light and heat conditions. Its tolerance to acid/alkali and chlorine oxidation surpasses that of other organophosphoric acids, making it ideal for harsh industrial environments. For instance, HEDP remains effective in systems operating at temperatures up to 250°C, as noted in NIST's standards for industrial chemical performance.

Technical Specifications

The following table outlines the key technical specifications of HEDP in both liquid and solid forms:

Items	Index (Liquid)	Index (Solid)
Appearance	Clear, Colorless to pale yellow aqueous solution	White crystal powder
Active Content (HEDP), %	58-62	90.0 min
Active Content (HEDP·H2O), %	-	98.0 min
Phosphorous Acid (as PO33-), %	2.0 max	0.8 max
Phosphoric Acid (as PO43-), %	0.8 max	0.5 max
Chloride (as Cl-), %	0.02 max	0.01 max
pH (1% water solution)	2.0 max	2.0 max
Density (20℃), g/cm3	1.40 min	-
Fe, mg/L	20.0 max	10.0 max
Color APHA (Hazen)	40.0 max	-
Ca Sequestration (mg CaCO3/g)	500.0 min	-

Applications in Industrial Processes

HEDP is extensively used in various industries due to its multifunctional properties. Key applications include:

• Circulating Cool Water Systems: HEDP prevents scale formation and corrosion in cooling towers, ensuring efficient heat transfer and extending equipment lifespan.
• Oil Fields: It inhibits scale and corrosion in pipelines and drilling equipment, reducing maintenance costs and downtime.
• Low-Pressure Boilers: HEDP protects boiler systems from mineral deposits and oxidative damage, enhancing thermal efficiency.
• Textile Industry: As a detergent for metals and non-metals, HEDP aids in fabric processing and dyeing.
• Dyeing Industry: It acts as a peroxide stabilizer and dye-fixing agent, improving color retention and fabric quality.
• Electroplating: HEDP serves as a chelating agent in non-cyanide electroplating, ensuring uniform coating and reducing defects.

The recommended dosage varies by application: scale inhibitor at 1–10 mg/L, corrosion inhibitor at 10–50 mg/L, and detergent at 1000–2000 mg/L. For optimal performance, HEDP is often combined with polycarboxylic acids.

Packaging and Storage

HEDP is available in both liquid and solid forms, with packaging tailored to customer requirements:

• Liquid: 200L plastic drums, IBC (1000L)
• Solid: 25kg/bag

Storage should be in a shaded, dry place for up to 12 months to maintain its efficacy.

Safety and Handling

As an acidic compound, HEDP requires careful handling. Users should:

• Wear protective gloves and goggles to avoid contact with eyes and skin.
• Rinse immediately with water if exposed to the skin or eyes.
• Ensure proper ventilation in storage and usage areas.

Synonyms and Related Terms

HEDP is known by numerous synonyms, including:

• Hydroxyethylidene-1,1-diphosphonic acid
• Etidronic acid
• 1-Hydroxy-1,1-ethanediyl ester
• Oxyethylidenediphosphonic acid (OEDP)

Key related products include scale and corrosion inhibitor chemicals and corrosion scale inhibitor for cooling towers.

Company Background: Hebei Longke Water Treatment Co., Ltd.

Hebei Longke Water Treatment Co., Ltd. is a leading manufacturer of water treatment chemicals in China, specializing in innovative solutions for industrial and municipal applications. With a commitment to quality and sustainability, the company has established itself as a trusted partner for industries requiring advanced water treatment technologies. Their products, including HEDP, are designed to meet stringent industry standards and environmental regulations.

Conclusion

HEDP is an indispensable compound in modern industrial operations, offering robust protection against corrosion and scale. Its versatility, combined with the expertise of Hebei Longke Water Treatment Co., Ltd., ensures that industries can maintain optimal performance and safety. As highlighted by the National Institute of Standards and Technology (NIST), the use of such advanced chemical solutions is critical for technological advancement and industrial efficiency.

References

National Institute of Standards and Technology (NIST) (2025). Standards for Industrial Chemical Performance. Retrieved from https://www.nist.gov/

Keywords: HEDP, scale and corrosion inhibitor chemicals, scale and corrosion inhibitor, corrosion scale inhibitor, scale and corrosion inhibitor for cooling tower