Sorption of cadmium and other heavy metals by pine bark

Pine bark sorbs cadmium ions from aqueous solutions. A decrease in the bark concentration with a constant cadmium concentration, or an increase in the cadmium concentration with a constant bark concentration, increased cadmium loading per unit weight of the adsorbent. An increase in the initial pH exhibited the same effect. The maximum cadmium uptake was obtained using very fine particles of pine bark. The isotherms presented in this work fit the Freundlich isotherm model reasonably well. A high concentration of soft and hard ions strongly depressed the uptake of cadmium by pine bark. Bark can be used for the sorption of the following metals from aqueous solutions with the indicated order of capacity (mass basis): Pb2+ > Cd2+ > Cu2+ > Ni2+ Generally, the same order of capacity was observed in a mixture containing these metal ions. Bark was found to respond better for sorption of metal ions when preloaded with another metal ion. (C) 1997 Elsevier Science B.V.