Biosorption of antimony(V) by freshwater cyanobacteria Microcystis biomass: Chemical modification and biosorption mechanisms

In this study, the biosorption of anionic Sb(OH)6− by chemically modified biomass of cyanobacteria Microcystis from Taihu Lake was investigated and the possible mechanisms were discussed. Acid treatment using 0.1 mol/L HCl significantly enhanced the biosorption as compared with the original biomass. The biosorption for both the original and acid-treated biomass decreased with the increase of pH with the optimal range being pH 2.5–2.6. The biosorption processes obey the Freundlich isotherm model. The reusability experiments demonstrated a desirable regeneration performance for both the original and acid-treated biomass in the repetitive biosorption–desorption cycles. However, the acid treatment resulted in higher biosorption capacities than the original biomass in the first three cycles. The results of zeta potential and ATR-IR suggest that the binding of Sb(OH)6− on the biomass occurred through electrostatic attraction and complexation. The ATR-IR spectra further confirmed the involvement of amino, carboxyl and hydroxyl groups in the removal of Sb(OH)6−. SEM–EDXA analyses indicate that the biosorption was highly heterogeneous. There was no change in the valence state of Sb(V) observed from the XANES spectra of Sb L edge for the biosorbed biomass. This study suggests promising biosorption potential of Microcystis to remove Sb(V) from wastewater.

► The biosorption of Sb(OH)6− by cyanobacteria Microcystis was investigated. ► Acid treatment enhanced the biosorption and the optimal range of pH was 2.5–2.6. ► Amino, carboxyl and hydrogen groups involved in the biosorption. ► HCl demonstrated the highest desorption efficiency.