Cork biomass as biosorbent for Cu(II), Zn(II) and Ni(II)

The removal of Cu(II), Zn(II) and Ni(II) from solutions using biosorption in cork powder is described. The adsorption isotherms were determined, along with the effect of different variables, such as the solid–liquid ratio, temperature and pH on the removal efficiency of the metals. The potentiometric titration curve of the cork biomass was determined and some zeta-potential studies were carried out. The effect of the pre-treatment by Fisher esterification on the biosorption properties of cork is also presented. It was concluded that the adsorption of the heavy metals was favoured by an increase in pH. The degree of heavy metal removal is directly related to the concentration of cork biomass, and the maximum sorption capacity of cork biomass for Cu(II), Zn(II) and Ni(II) was 0.63, 0.76 and 0.34 meq./g, respectively. It is shown that ion exchange plays a more important role in the sorption of Cu(II) and Ni(II) on cork biomass than in the sorption of Zn(II). The pre-treatment by Fisher esterification confirmed the important role of the carboxylic groups in binding of Cu(II) and Ni(II) and showed that they are the only binding sites for Zn(II).