The ambient temperature adsorption of the metal cations Zn2+, Cu2+ and
Pb2+ on Pinus pinaster bark pretreated with acidified formaldehyde so
lution, and particularly the influences of the pretreatment conditions
and of the pH of the cation solution on the adsorption capacity of th
e bark, were investigated. The equilibrium data were satisfactorily fi
tted by Freundlich isotherms. The bark was an excellent adsorbent, sui
table for removal of toxic ions from wastewater with efficiency compar
able to commercially available adsorbents, but at a reduced cost.