Lead (II) and zinc (II) ions removal capacity of coarse limestone and rhyolite tuff from aqueous solutions

The heavy metal adsorption capacity of natural stones is important because it has influence on the dispersion of pollutants. Lead (II) and zinc (II) ions removal capacity of two Hungarian stones (coarse limestone and rhyolite tuff) were analysed under laboratory conditions. Petrophysical parameters of rock samples were determined at air-dried and in water saturated conditions: apparent density, capillary water absorption, ultrasound pulse velocity, open and full porosity. The powdered rock samples and specimens were put into lead-nitrate and zinc-sulphate solutions and the amounts of adsorbed lead (II) and zinc (II) ions were identified by titration of the residual solution. According to the tests, the powdered and cylindrical rock specimens could reduce the concentration of lead (II) and zinc (II) ions in the heavy metal solutions. The results suggest that these two types of rocks could be used in environmental protection technologies such as material of permeable reactive barrier. [PUBLICATION ABSTRACT]