Efficient removal of U(VI) from aqueous solutions using the magnetic biochar derived from the biomass of a bloom-forming cyanobacterium (Microcystis aeruginosa)

The utilization of Microcystis biomass is an urgent issue in the mitigation of cyanobacterial bloom. In this study, Microcystis-derived biochar (MB) and Fe3O4-modified biochar (Fe3O4/MB) were fabricated for the U(VI) elimination. The results showed that U(VI) sorption process by either MB or Fe3O4/MB was pH-dependent and ionic strength-independent. The maximum sorption capacity of MB was higher than that of Fe3O4/MB. According to the analysis of X-ray photoelectron spectroscopy, U(VI) sorption on both MB and Fe3O4/MB was mainly ascribed to the surface complexation between U(VI) and oxygencontaining functional groups on the surface of MB. Fe3O4 particles on the surface of MB didn't provide extra active sites for the sorption of U(VI), but it enabled the adsorbent to be magnetically separated. Five consecutive sorption/desorption cycles verified the good reusability of Fe3O4/MB in this study. Therefore, the investigation is not only meaningful for the utilization of nuisance biomass from cyanobacterial blooms, but also provides novel adsorbents for the U(VI) removal from aqueous solutions. (C) 2020 Elsevier Ltd. All rights reserved.