Comparison of the ability of limestone and concrete to remove heavy metal ions from contaminated water

Abstract

The dissolving potential of the Ca–minerals in concrete and limestone; and precipitation potential of metal ions from model acid water has been examined with attention to change of pH during the batch tests (L/S ratio = 300 ml /0.5 g, L = model solution with Mx+ (Ni; As; Zn; Cu; Fe) cations and (SO4)2- anion). Both of materials are the source of alkalinity-generating and move pH of acid solution to alkali region. The neutralization initiates the precipitation of metal contaminants in form of insoluble compounds. It was confirmed, that concrete is able to edit pH value more significantly at test conditions than limestone (calcite) if the initial pH of water is > 1.5. Main effective compound of concrete is the portlandite – Ca(OH)2. The fact that concrete generated more alkaline environment during two hours tests the metal ions have been removed from water by concrete more effectively (100 %).