Volcanic tuff and walnut shells were tested as natural adsorbents materials for
the removal of Pb(II) and As(V) from waste water. Inductively coupled plasma mass
spectrometer (ICP-MS) and an atomic absorption spectrometer were used to monitor the
concentration of metal ions in aqueous systems. The sorption capacity of these adsorbents
were evaluated at different experimental conditions. The effect of time, initial concentration
of the metals and the adsorbent dose on the adsorption was studied. The lead removal
efficiency using volcanic tuff at pH value of 4 was more than 99 % in all concentration
range investigated, while in the case walnut shells at pH value of 2, the maximum
efficiency was 53.2%. Regarding the arsenic uptake at low concentration, the best
performance was registered for walnut shells (50.15%). The two low-cost natural sorbents
were efficient to remove both pollutants from aqueous systems and may be considered as a
viable alternative to conventional adsorbents. | 
