Application of coconut shell, banana peel, spent coffee grounds, eucalyptus bark, piassava (Attalea funifera) and water hyacinth (Eichornia crassipes) in the adsorption of Pb2+ and Ni2+ ions in water

In this study, six residual plant materials were tested as adsorbents to remove Pb2+ and Ni2+ ions from water. The influence of variables such as PH, contact time and adsorption isotherms parameters in adsorption process was studied. The assessment of compatibility with cement of the used contaminated adsorbents has also been performed. The concentration of the studied metal ions was determined by dispersive energy x-ray fluorescence spectrometry. In the studies of pH and kinetics, it was verified that Pb2+ ions were more adsorbed than the Ni2+ ions. The highest values for adsorption capacity were found at pH equal to 4.5 for Pb2+, and at pH equal to 5 for Ni2+. The adsorption kinetics were fitted to the pseudo-second order model for the both metals. The Langmuir isotherm allowed to estimate the adsorption capacity of the materials for mono and bicomponent solutions, which were superior to those observed in literature. A new proposal for the final destination of the used adsorbents contaminated with metal ions, proved to be a viable alternative for its immobilization.