Chemical	HEDP (1-Hydroxyethylidene-1,1-diphosphonic acid)
CAS No.	2809-21-4
General Introduction	Hydroxyethylidene-1,1-Diphosphonic Acid (HEDP) 98% is a high-performance organophosphonic acid corrosion and scale inhibitor. With CAS No. 2809-21-4, molecular formula C₂H₈O₇P₂, and molecular weight 206.02, this product is engineered to deliver exceptional performance in industrial water treatment and related applications. As a core water treatment chemical, HEDP 98% stands out for its ability to chelate with metal ions (Fe, Cu, Zn) to form stable complexes, dissolve oxide layers on metal surfaces, and maintain efficiency even under extreme conditions. It is widely recognized for its versatility, making it a preferred choice in sectors ranging from power generation to pharmaceuticals.

Sepcifications
Item	Index
	50% Liquid	60% Liquid	Solid
Appearance 外观	Colorless or light yellow transparent liquid	Colorless or light yellow transparent liquid	White crystal powder
活性酸含量 Active acid (as HEDP),%	≥ 50.0%	≥ 60.0%	--
亚磷酸（以PO₃³⁻计） Phosphorous acid (as PO₃³⁻),%	≤ 2.0%	≤ 2.0%	≤ 0.8%
磷酸（以PO₄³⁻计） Phosphoric acid (as PO₄³⁻),%	≤ 0.8%	≤ 0.8%	≤ 0.5%
氯化物（以Cl⁻计） Chloride (as Cl⁻) , %	≤ 0.02%	≤ 0.02%	≤ 0.01%
密度（20℃） Density (20℃), g/cm³	≥ 1.36 g/cm³	≥ 1.40 g/cm³	--
pH值（1%水溶液） pH (1% water solution)	1.5-2.0	1.5-2.0	1.5-2.0
钙螯合物值，mg·g⁻¹ Calcium Chelation Value, mg·g⁻¹	≥450	≥500	--
铁（以Fe²⁺计）含量，mg·L⁻¹ Iron (as Fe²⁺) Content, mg·L⁻¹	≤ 20.0	≤ 20.0	≤ 10.0
Active Component (as HEDP·H₂O) /%	--	--	≥97.0

HEDP 98% Solid - Core Functions
1. High-Temperature Stability	HEDP 98% retains its scale and corrosion inhibition effectiveness at temperatures up to 250°C, outperforming many conventional water treatment chemicals in high-heat environments such as industrial boilers and oilfield systems.
2. Chemical Durability	This product exhibits excellent chemical stability under high pH conditions, resisting hydrolysis and decomposition from light, heat, or oxidizing agents (e.g., chlorine). Its tolerance to acids, alkalis, and oxidation is superior to other organophosphonic acids, ensuring long-lasting performance in diverse water systems.
3. Chelation & Synergistic Effects	HEDP 98% forms hexavalent chelating complexes with metal ions in water, particularly calcium ions, delivering strong antiscale effects and a notable threshold effect. When blended with other water treatment chemicals (e.g., polycarboxylates), it enhances overall efficiency through synergistic interactions.
4. High Purity for Specialized Use	In its solid form, HEDP 98% is a high-purity white crystalline powder, ideal for cold climates. Its purity also makes it suitable for sensitive applications like electronics cleaning and as an additive in daily chemicals.

HEDP 98% Solid - Applications
1. Industrial Circulating Water Systems	HEDP 98% is widely used as a scale and corrosion inhibitor in circulating cooling water systems, low-pressure boilers, and oilfield operations across power, chemical, metallurgy, and fertilizer industries. Its chelating action prevents scale buildup, reducing maintenance costs and improving system efficiency.
2. Metal & Nonmetal Cleaning Agents	In the light textile industry, HEDP 98% serves as an effective cleaning agent. It dissolves metal ions without aggressive damage to substrates, ensures easy passivation after pickling, and minimizes rust formation—critical for maintaining material integrity.
3. Dyeing & Bleaching Auxiliaries	As a peroxide stabilizer and dye-fixing agent in the dyeing industry, HEDP 98% enhances color retention and prevents peroxide degradation, ensuring consistent results in textile processing.
4. Cyanide-Free Electroplating	It acts as a reliable chelating agent in cyanide-free electroplating, improving coating adhesion and uniformity while supporting eco-friendly plating practices.
5. Pharmaceutical Industry	HEDP 98% functions as a carrier for radioactive elements in pharmaceutical applications, leveraging its stability and chelation properties for controlled delivery.