Abstract
Over the past few decades, the removal and recovery of Lanthanum (La) has received great economic and environmental interest due to its high market prices, along with several industrial applications. Recently, with the increasing demand for rare-earth compounds with high purity, the separation and purification of these elements has gained expressive attention. The bio/adsorption has been considered an alternative for the recovery of these elements, due to their simplicity, low cost and efficiency in the recovery of rare earth ions in low concentrations. In this study, particles produced from a blend of sericin and alginate crosslinked by proanthocyanidins (SAPAs); calcined Verde-lodo clay and calcined Bofe clay; aquatics macrophytes Salvinia natans and Pistia Stratiotes, were used to remove lanthanum ion from aqueous solutions. The simulation of speciation diagrams as functions of pH was performed using Hydra/Medusa software and the pH was adjusted and controlled during the experiments to values between 4.5 and 5.0. The affinity tests study were performed in batch systems at concentration of 1.0 and 3.0 mmol L-1 La3+. In the experiments with concentration of 1.0 mmol L-1 La3+, all bio/adsorbents evaluated presented a high removal percentage (>96%). The removal percentage and adsorption capacity of lanthanum ion from aqueous solution by bio/adsorbents materials varied between 53.47 to 98.26% and 0.154 to 0.243 mmol g-1 at the concentration of 3.0 mmol L-1 La3+, respectively. The results indicated that the material with the greatest values of removal percentage and adsorption capacity for lanthanum ions was the particles of sericin and alginate crosslinked by proanthocyanidins (82.66 % and 0.243 mmol g-1).
