The Relevance of Leaching

In many respects leaching hehavior as reflected by the pH dependence leaching test and related characterisation leaching tests provides a better means of assessing environmental impact than analysis of total composition.

The pH dependence test (CEN/TS 14429) can be used as a basis of reference for many other existing leaching tests as illustrated by the figure. Relevant pH domains are related to different soil uses and types of exposures.

Thus many different questions can be addressed in relation to the pH domain relevant for material use, application or treatment.

Worldwide more than 50 leaching tests can be identified. For characterization of materials there is no need for 50 tests. Many tests will show common characteristics. Here agreement between a variety of tests and the pH dependence leaching test is illustrated indicating that the pH dependence leaching test is a generic characterization test, to which most of the other individual tests can be linked. Tests based on EDTA as complexant are an exception, but the function of this test can better be obtained by acid than by a selective chemical.