Pb(II) adsorption by a novel activated carbon – alginate composite material. A kinetic and equilibrium study

The adsorption capacity of an activated carbon – calcium alginate composite material (ACAA-Ca) hasbeen tested with the aim of developing a new and more efficient adsorbent material to remove Pb(II) ionfrom aqueous solution. The study was carried out at pH = 5, in NaCl medium and in the ionic strengthrange 0.1–0.75 mol L−1. Differential Pulse Anodic Stripping Voltammetry (DP-ASV) technique was usedto check the amount of Pb(II) ion removed during kinetic and equilibrium experiments. Different kinetic(pseudo first order, pseudo second order and Vermuelen) and equilibrium (Langmuir and Freundlich)models were used to fit experimental data, and were statistically compared.Calcium alginate (AA-Ca) improves the adsorption capacity (qm) of active carbon (AC) in the ACAA-Caadsorbent material (e.g., qm= 15.7 and 10.5 mg g−1at I = 0.25 mol L−1, for ACAA-Ca and AC, respectively).SEM-EDX and thermogravimetric (TGA) measurements were carried out in order to characterize thecomposite material. The results of the speciation study on the Pb(II) solution and of the characterization ofthe ACAA-Ca and of the pristine AA-Ca and AC were evaluated in order to explain the specific contributionof AC and AA-Ca to the adsorption of the metal ion.