Valorization of the saline slags generated during secondary aluminium melting processes as adsorbents for the removal of heavy metal ions from aqueous solutions

摘要

This work describes the surface properties of saline slags generated during secondary aluminium melting processes and the application of these materials as adsorbents for the removal of Cd(H), Cu(II), Pb(II) and Zn(II) from aqueous solutions. Saline slags were chemically treated with aqueous solutions of HNO3, H2SO4 and NaOH of varying concentrations (0, 0.5, 1, 1.5 and 2 mol/dm3) for 0.5, 4 and 24 h. Nitrogen adsorption at-196 C was used to study the textural properties of the solids. The specific surface area and pore volume decrease as the chemical reagent concentrations and duration of the treatments increase; Solids with a surface area of up to 109 m~2/g are obtained. The adsorption of heavy metal ions has been studied in terms of pseudo-first-order and pseudo-second-order kinetics, and several isotherm models have also been applied to the equilibrium adsorption data at various pH values. The adsorption capacity of the saline slags was maintained after several cycles of reuse.