Abstract

Pine bark is a substrate which allows the attachment and de-activation of heavy metal ions, thereby cleansing the host solution. The present work was aimed at studying the removal of binary heavy metal ions from aqueous solutions using pine bark and to explore the possibility of elution as a subsequent stage for releasing and concentrating the metal ions. The application of the method to the cases of Cu(II) and Zn(II) ions is presented. The adsorption of each metal ion separately from binary mixtures onto pine bark was studied. Subsequently, the loaded bark was used to perform elution experiments leading to the concentration of the metal ions and their further retrieval. Tests showed that the adsorption capacity of pine bark towards Cu(II) and Zn(II) ions from a mixture of the same in aqueous solution was almost 0.35 mmol metal ion/g dry bark. The same value was obtained by adding the individual adsorption capacities, determined when each metal ion was adsorbed separately. Cyclic percolation processes resulted in the concentration of the metal ions, showing increases of almost 20- and 10-times for Cu(II) and Zn(II) ions, respectively.