Formation of Sludges or Precipitates

The use of corrosion inhibitors is often accompanied by treatment with other additives such as scale inhibitors, dispersants, or bactericides. These additives may react with the inhibitor to produce sludges or precipitates that have no protective properties and that may consume the inhibitor, thereby reducing its concentration in the solution. 

Two kinds of tests should be carried out to determine the effects of mixing if the chemical structure of each additive is not already known. A bottle test should be carried out in which relatively concentrated solutions of the two additives are mixed and observed for gross reactions, such as the formation of a precipitate. 

The second test is one in which each of the additives was originally evaluated. In this test, the additives are mixed at the low concentrations used in treatment and the test results of the mixture are compared with the results using the additive alone. If a significant loss of effectiveness is observed with the mixture, the materials should be considered incompatible. 

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