Sorption of heavy metal from aqueous solution by volcanic ash

Lava ash from Mt. Etna volcano has been tested in a series of batch experiments in order to find out its suitability to act as metal ion sorbent from wastewaters. The results show that the removal of Cd, Cu and Cr elements reaches a suitable level. Various experimental parameters have been tried to verify their influence on the metal sorption. Each ionic species in solution can be removed only in its own range of optimal pH. No competitive effects have been found. The equilibrium data are satisfactorily fitted by the Freundlich isotherm. Desorption experiments by acid aqueous solutions result in leaching of negligible amounts of metal ions.