Gellan gel beads containing magnetic nanoparticles: An effective biosorbent for the removal of heavy metals from aqueous system

This study describes an efficient adsorbent consisting of magnetic Fe3O4 and gellan gum, which couples magnetic separation with ionic exchange for heavy metal removal. Adsorption kinetics analysis showed that the adsorption capacities were in an order of Pb2+ > Cr3+ > Mn2+. Different experimental parameters studies indicated that adsorbent dosage, initial metal concentration, temperature and initial pH played important roles in adsorption process. Additionally, the Freundlich model gave a better fit to the experimental data than the Langmuir model. Chemical analysis of calcium ions released into the bulk solutions demonstrated that carboxyl group is critical for binding Pb2+, Mn2+ and Cr3+. Furthermore, a high desorption efficiency was obtained by sodium citrate.