Removal of heavy metal ions from solutions by coniferous barks

The abilities of 15 coniferous barks for removing toxic heavy metal ions were investigated. The barks considerably varied in the adsorption ability to each metal ion. Of the barks tested, high adsorption ability for heavy metal ions was found in Picea abies (Norway spruce). Equilibrium experiments using P. jezoensis (Yezo spruce) bark showed that the adsorption of Cd2+ was greatly affected by the pH of solution and the initial Cd2+ concentration in solution. The adsorption of Cd2+ by P. jezoensis bark followed Freundlich isotherm in the concentration range 10-330 mg Cd2+/L. The continuous column experiments using P. jezoensis bark indicated that the packing had retained 10.1-14.2 mg Cd2+/g adsorbent until the column broke through.