Adsorptive removal of Sb(III) from wastewater by environmentally-friendly biogenic manganese oxide (BMO) materials: Efficiency and mechanisms

Antimony(Sb(III)) contamination in wastewater has raised global concerns due to its high toxicity. The efficiency and mechanisms of Sb(III) adsorptive removal from wastewater with environmentally-friendly biogenic Mn oxide (BMO) materials as adsorbent were investigated, based on kinetic experiments and multispectroscopic analyses. Kinetic experiments showed that after 300 min of reaction, 97.79–100% of Sb(III) and 85.60–92.92% of total Sb were removed, indicating that BMO can quickly and effectively oxidize Sb(III) and sequester Sb(V) from water. The bacterial activity in BMO did not significantly affect Sb(III) removal, but a decrease in the release of Mn(II) into solution may provide new reactive sites for the re-oxidation of Sb(III). X-ray photoelectron spectrometer (XPS) high-resolution analysis suggested that Sb(V) was the only speciation remaining in the solid phase after the reaction of Sb(III) with BMO. X-ray diffraction (XRD) results further showed that the fast oxidation of Sb(III) by BMO led to the production of Mn(II) antimonate (Mn₂Sb₂O₇) precipitates. Successive extraction experiments confirmed that residual fraction (67.49–83.62%) and Mn oxide bound fraction (13.18–29.72%) were the dominant fractions of Sb(III) after 300 min of reaction, which were relatively stable and had low leaching risks. These findings indicated that BMO performed well in removing Sb(III) from wastewater. Copyright © 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.