Use of fractional factorial design for optimizing removal of nickel, copper, cadmium and lead by buriti modified fibers

RESUMO – The adsorption of copper, cadmium, lead and nickel in mono-element and multielement aqueous solutions onto buriti modified fibers was studied. The fractional factorial design 2 showed that pH, adsorbent mass, agitation rate and initial metal concentration influenced each metal adsorption differently. The kinetics and thermodynamic equilibrium parameters were obtained for all elements. The results showed that the order of mono-element adsorption for these three contaminants is Ni> Cd> Pb> Cu. The adsorption kinetics were fitted to the pseudo-second order model, giving linear correlation coefficients higher than 0.98. The Langmuir isotherm provided the best fit with the monoelement experimental data. In this study, the multi-element system isotherms were also obtained and a significant difference was found in the competitiveness for the site and the adsorption capacity order was Ni> Cu> Cd> Pb.