Can you use hydrochloric acid as an antiscalant?

Answer 1

No, but it may still help you achieve your goal.

Supposing your main scaling agent is calcium carbonate, acidification will help you as calcium carbonate is less prone to precipitation in acidic conditions.

Hydrochloric acid has an action on the equilibrium of the ions in solution, but does not have any antiscalant properties.

However the use of acid in industrial systems brings its own set of problems.

When used in reverse osmosis applications, the permeate quality will lower (salt rejection by the membrane is considered constant therefore if the ionic strength of the raw water increases, the ion content of the permeate increases too... QED).

If the water is buffered (presence of carbonates), large quantities of acid may be needed. There might be a cost issue as well as a handling issue. Concentrated HCl is not exactly nice stuff to handle and equipment tends to corrode in the presence of HCl vapours.

Antiscalants, on the other hands, will enable supersaturation of the solution. Different molecules with different modes of action and efficiencies can be used :

- polymers

- chelating agents

- phosphate based compounds

For more info, you can always check the website of Genesys International (my employer) :

www.genesysro.com

I hope this answers your question.