How About Hydroxyethylidene Diphosphonic Acid For Scale Inhibitor And Metal Cleaning Agent?

Hydroxyethylidene diphosphonic acid is an organic phosphonic acid that can be used in many fields. Hydroxyethylidene diphosphonic acid and its sodium salts are called all-purpose organic phosphine products. Hydroxyethylidene diphosphonic acid has occupied a large proportion of global sales of corrosion inhibitors. Let's take a look at the amazing performance of HEDP as a metal cleaner and a scale inhibitor.

The cleaning temperature of hydroxyethylidene diphosphonic acid used as a metal cleaning agent is generally 50 ~ 85 °C. Dilution oil cleaning temperature is 50~60°C. Heavy oils have a higher temperature of higher melting point oils. The cleaning time of the hydroxyethylidene diphosphonic acid cleaning agent is related to the cleaning method. According to the characteristics of the cleaning agent, the cleaning time is 2 to 10 minutes or more.

Cleaning methods include immersion cleaning, spray cleaning, ultrasonic and multi-stage cleaning. The cleaning process is generally: washing, rinsing, dehydration and rust-proof treatment.

For example, the pre-plating cleaning process for oil contaminated parts is as follows. Degreasing, washing, pickling, washing, alkaline soaking (ultrasonic), anodic electrolytic cleaning, washing, activating, washing and plating.

Hydroxyethylidene diphosphonic acid is a typical metal cleaning agent. It has its own acidity and excellent chelating activity. This acid can chelate, dissolve and disperse special dirt such as oxide layer adhering to the metal surface to achieve the purpose of cleaning.

As for the organic phosphonic acid, its inhibition mechanism is an electrodeposition film. The organic phosphonic acid in the water is a negatively charged ion. It reacts with calcium ions in water. They produce a positive and negative charge of complexing ions “Na2Ca2P6O6“. Relying on the current generated during metal corrosion, this complex is deposited on the metal surface. This will hinder the contact of oxygen with metal. In this way, the effect of suppressing corrosion can be achieved. Therefore, phosphine-based formulations require a certain concentration of calcium ions in water. Other organophosphorus scale inhibitors (such as DTPMP, PAPEMP) work in the same way.

Several kinds of corrosion inhibitors are used together with certain proportions, which is smaller than the amount used alone, and the effect is better. This is the so-called "synergy effect".

Scale inhibitors remove and prevent scaling, improve heat transfer efficiency, and reduce energy and fuel consumption. In the water treatment industry, hydroxyethylidene diphosphonic acid can also reduce sewage discharge and increase water utilization.

Hydroxyethylidene diphosphonic acid is used as a scale inhibitor to disperse insoluble inorganic salts in water. hydroxyethylidene diphosphonic acid scale inhibitors prevent or interfere with precipitation and scaling of insoluble inorganic salts on metal surfaces. At the same time, hydroxyethylidene diphosphonic acid scale inhibitors can maintain good heat transfer performance of metal equipment.


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