The Role and Advantages and Disadvantages of HEDP Salts
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irowater
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The Role and Advantages and Disadvantages of HEDP Salts


HEDP Salts is an anode type corrosion inhibitor. In neutral and alkaline environments, HEDP Salts' corrosion inhibition of carbon steel relies mainly on dissolved oxygen in the water. The dissolved oxygen reacts with the steel to form a thin γ-Fe2O3 oxide film: the growth of this oxide film cannot be completed quickly but takes a considerable amount of time. During this time, electrochemical corrosion continues at the gap of the oxide film. These gaps can be either blocked by continuously growing iron oxide or blocked by insoluble iron phosphate to protect the carbon steel.

Since HEDP Salts is prone to form calcium phosphate with a small solubility product with calcium ions in water, HEDP Salts has rarely been used alone as a cooling water corrosion inhibitor. Similarly, positive HEDP Salts produced by the hydrolysis of poly HEDP Salts are treated as components that require strict control, although it also has a certain inhibition effect.

In recent years, HEDP Salts has been used as a cooling water corrosion inhibitor since the development of a series of copolymers with high inhibition of calcium phosphate scale, such as acrylic acid and hydroxypropyl acrylate, but it needs to The above copolymers are used in combination.

The advantages of HEDP Salts are:
1 no poisons;
2 cheaper.

Its disadvantages are:
1 need to be used in combination with a special copolymer;
2 corrosion inhibition is not too strong;
3 easy to promote the growth of algae in cooling water.
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