CAS No.：2809-21-4
Alias: Hydroxyethylidene diphosphonic acid, HEDPA, (1-Hydroxyethylidene)diphosphonic acid, 1-Hydroxyethylidene-1,1-diphosphonic acid
Molecular formula: C2H8O7P2
Relative molecular mass: 206.02
Structural formula: I. Properties and Applications
HEDP is an organic phosphonic acid scale and corrosion inhibitor that can form stable complexes with various metal ions such as iron, copper, and zinc, and can dissolve oxides on metal surfaces. It remains effective in corrosion and scale inhibition at temperatures up to 250°C, is stable under high pH conditions, resistant to hydrolysis, and generally does not decompose under normal light and heat conditions. It has better acid and alkali resistance and chlorine oxidation resistance compared to other organic phosphonates. It can form six-membered ring chelates with metal ions in water, especially calcium ions, providing excellent scale inhibition and a significant threshold effect. When used in combination with other water treatment agents, it exhibits ideal synergistic effects.
HEDP solid is a high-purity product suitable for extremely cold winter regions; particularly suitable for cleaning agents in the electronics industry and additives in daily chemicals.
HEDP is widely used in industrial circulating cooling water systems such as power, chemical, metallurgical, and fertilizer industries, as well as in medium and low-pressure boilers, oilfield water injection, and oil pipeline scale and corrosion inhibition. In the light and textile industries, it can be used as a cleaning agent for metals and non-metals, a stabilizer for peroxides and a color fixative in dyeing and bleaching industries, a complexing agent in non-cyanide electroplating, and a carrier for radioactive elements in the pharmaceutical industry.
II. Technical Specifications Complies with HG/T 3537-1999 Item | Specification | HG/T 3537-1999 | | Appearance | Colorless or light yellow transparent liquid | White powdery solid | Active component (as HEDP) % ≥ | 50.0 60.0 | 89.0 | Phosphite (as PO33-) % ≤ | 2.0 2.0 | 0.80 | Phosphate (as PO43-) % ≤ | 0.8 0.8 | 0.50 | Chloride (as Cl-) % ≤ | 0.01 0.01 | 0.01 | pH (1% aqueous solution) ≤ | 2 2 | 2.0 | Density (20°C) g/cm3 ≥ | 1.34 1.40 | —— | Calcium chelation value mg/g | 450 500 | —— | Iron (as Fe2+) content mg/L ≤ | 10 10 | 5.0 | Active component (as HEDP H2O) % ≥ | —— | 98.0 |
III. Usage Method
As a scale inhibitor, HEDP is typically used at concentrations of 1–10 mg/L; as a corrosion inhibitor, 10–50 mg/L; as a cleaning agent, 1000–2000 mg/L. It is usually used in combination with polycarboxylic scale inhibitors. For other applications, the dosage should be determined through testing. IV. Packaging and Storage
HEDP liquid is packaged in plastic drums, 30 kg or 250 kg per drum; HEDP solid is packaged in plastic woven bags lined with polyethylene bags, 25 kg net weight per bag, or as required by the customer. Store in a cool, ventilated indoor area, protect from moisture, with a shelf life of twelve months. V. Safety Precautions
HEDP is acidic. Use appropriate labor protection during operation. Avoid contact with skin and eyes. In case of contact, rinse immediately with plenty of water. |
