1-Hydroxy Ethylidene-1,1-Diphosphonic Acid （HEDP）

Aliases: Hydroxyethylidene Diphosphonic Acid, HEDPA, (1-Hydroxyethylidene) Diphosphonic Acid, 1-Hydroxyethylidene-1,1-Diphosphonic Acid
CAS No.: 2809-21-4
Molecular Formula: C₂H₈O₇P₂
Relative Molecular Mass: 206.03
Structural Formula:

Performance and Applications

HEDP is an organophosphonic acid scale and corrosion inhibitor. It can form stable complexes with various metal ions such as iron, copper and zinc, and can dissolve oxides on the metal surface. It still maintains excellent corrosion and scale inhibition performance at 250℃, is highly stable at high pH values, is not easy to hydrolyze, and is not easy to decompose under general light and heat conditions. Its acid and alkali resistance, and chlorine oxidation resistance are better than other organophosphonic acids (salts). It can form six-membered ring chelates with metal ions in water, especially calcium ions, thus it has good scale inhibition effect and obvious threshold effect. When used in combination with other water treatment agents, it exhibits an ideal synergistic effect.

HEDP solid is a high-purity product, suitable for severe cold regions in winter; especially suitable for cleaning agents in the electronic industry and additives for daily chemicals.

HEDP is widely used in scale and corrosion inhibition of industrial circulating cooling water systems in electric power, chemical, metallurgical, fertilizer and other industries, as well as medium and low pressure boilers, oilfield water injection and oil pipeline transportation. In the light textile industry, it can be used as a cleaning agent for metals and non-metals, a peroxide stabilizer and fixing agent in the bleaching and dyeing industry, a complexing agent in cyanide-free electroplating industry, and a carrying agent for radioactive elements in the pharmaceutical industry.

Technical Specifications

Usage Method

The general concentration of HEDP is 1~10mg/L when used as a scale inhibitor; 10~50mg/L when used as a corrosion inhibitor; 1000~2000mg/L when used as a cleaning agent. It is usually used in combination with polycarboxylic acid type scale inhibitor dispersants. When used in other industries, the dosage shall be determined according to tests.

Packaging and Storage

HEDP liquid is packed in plastic drums, Standard capacities: 25kg, 250kg, 1250kg (IBC tank).Note: Packaging weight can be adjusted according to customer requirements. HEDP solid is packed in plastic woven bags lined with polyethylene bags, with a net weight of 25kg per bag, or customized according to user requirements. Store in a cool and ventilated indoor place, keep away from moisture. The shelf life is twelve months.

Safety Protection

HEDP is acidic. Pay attention to labor protection during operation. Avoid contact with skin, eyes, etc. In case of contact, rinse immediately with plenty of clean water.