1-Hydroxyethylidene-1,1-diphosphonic acid, 2809-21-4, Hydroxy Ethylidene Diphosphonic acid (HEDP), HEDP, HEDPA, Etidronic acid, 2809-21-4

1-Hydroxyethylidene-1,1-diphosphonic acid, 2809-21-4, Hydroxy Ethylidene Diphosphonic acid (HEDP), HEDP, HEDPA, Etidronic acid, 2809-21-4

CAS: 2809-21-4

Molecular Formula: C2H8O7P2

Names and Identifiers

Physico-chemical Properties

Risk and Safety

Upstream Downstream Industry

Nature

colorless to light yellow viscous liquid. The pure product is a colorless, amorphous Crystal, miscible with water. Soluble in water, methanol, ethanol. It has a large dissociation constant in water and can form stable chelates and complexes with metal ions. It can form a stable adduct with a compound containing active oxygen, and keep the active oxygen stable. Chlorine resistance is good. Industrial product content is generally 50% ~ 62% colorless to light yellow viscous transparent aqueous solution, is a kind of Polybasic acid, soluble in water. HEDP is an important chelating agent, which is stable with several metal ions and is not easy to hydrolyze. It is not decomposed under General light and heat conditions, but is not resistant to the action of oxidative biocide. About 30% of HEDP with 5mg/L of residual chlorine is decomposed.

Preparation Method

prepared by the reaction of phosphorus trichloride, glacial acetic acid and water. Alternatively, it is prepared by the reaction of orthophosphoric acid, acetic anhydride and acetyl chloride. It can also be prepared by reacting phosphorous acid with acetic anhydride. It is also possible to react with acetic anhydride from orthophosphoric acid.

Introduction

This product is an organic phosphonic acid scale and corrosion inhibitor, which can form stable complexes with iron, copper, zinc and other metal ions, and can dissolve oxides on the metal surface. It can play a good role in corrosion and scale inhibition at 250 ℃, is still stable at high pH value, is not easy to hydrolyze, and is not easy to decompose under general light and heat conditions. Acid and alkali resistance and chlorine oxidation resistance are better than other organic phosphonic acids (salts). It can form a six-ring chelate with metal ions in water, especially calcium ions, so it has a good scale inhibition effect and an obvious solution limit effect. When combined with other water treatment agents, it shows ideal Synergistic effect.

Use

is the boiler and heat exchanger Scale Inhibitor and corrosion inhibitor, non-cyanide plating complexing agent, soap chelating agent, metal and non-metallic cleaning agent. As a water treatment agent, HEDP has a stable structure and is not easily hydrolyzed. The corrosion and scale inhibition effect is good. HEDP is a cathode corrosion inhibitor, and the corrosion inhibition rate is about 4 times higher than that of inorganic polyphosphate. The inhibition effect of iron ion in water on HEDP is obviously affected. When the concentration of iron ion is more than 3mg/L, the inhibition effect of HEDP decreases exponentially with the increase of iron ion concentration. HEDP is used in combination with other corrosion inhibitors and scale inhibitors, such as chromate, polyphosphate, molybdate, silicate, nitrite, zinc salt, polycarboxylate and its derivatives, which has synergistic effect and can improve the efficacy. The dosage used is low, and the dosage used in the composite formulation is generally 2 to 5mg/L.

Safety

is a low toxicity product. 60% hydroxy ethylene diphosphonic acid aqueous solution, rat oral LD50:2400mg/kg; Rabbit skin absorption LD50 greater than 7940mg/kg. Corrosive. It has moderate irritation to eyes and skin, and the staff should be well protected. If the skin and eyes are accidentally touched, it should be rinsed with plenty of water immediately. During storage, ventilation should be maintained to avoid exposure to the sun. Avoid with strong alkali and storage, mixed transport.

Reference Information