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 FeO-modified biochar (FeO/MB) were fabricated for the U(VI) elimination. The results showed that U(VI) sorption process by either MB or FeO/MB was pH-dependent and ionic strength-independent. The maximum sorption capacity of MB was higher than that of FeO/MB. According to the analysis of X-ray photoelectron spectroscopy, U(VI) sorption on both MB and FeO/MB was mainly ascribed to the surface complexation between U(VI) and oxygen-containing functional groups on the surface of MB. FeO 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 FeO/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.