Solidification of Cd-bearing zeolitic tuff by reaction with lime.

This article aims to find a reliable procedure by which to remove Cd(2+) from water and store it safely. The proposed procedure includes Cd(2+) uptake by a zeolitic tuff, a natural cation exchanger, followed by stabilization of the contaminated solid in a hardened lime matrix. Several tuff-lime pastes were examined and their safety tested by cation leaching and mechanical strength measurement. It was demonstrated that a very cheap mixture, containing only 10% lime, is able to safely retain the harmful cation and may be disposed of in a segregated landfill.