Facile template-free fabrication of iron manganese bimetal oxides nanospheres with excellent capability for heavy metals removal.

Iron manganese bimetal oxides (IMBO) nanospheres were synthesized via a facile and environmentally friendly template-free approach. The obtained IMBO with large surface area and abundant surface functional groups exhibited excellent performance for heavy metals removal from aqueous solution, with the maximum adsorption capacities of As(V) and Cr(VI) were 132.77mg/g and 105.96mg/g, respectively. The adsorption mechanism study confirmed that except for electrostatic attraction, both surface hydroxyl group (OH-) and carbonate group (CO32-) simultaneously played a key role in the ion-exchange process with As(V) and Cr(VI) species, which finally formed inner-sphere surface complexes on the interface of IMBO. Furthermore, the remarkable removal of As(V) and Cr(VI) by fixed-bed column was also observed in the presence of various commonly competing anions, and the effective working capacities of IMBO for As(V) and Cr(VI) were approximately 410 pore volume (PV) and 320 pore volume (PV) when the breakthrough point was set at 10ppb. The exhausted IMBO could be easily regenerated by using a NaOH solution (0.1M). These results demonstrated that this IMBO was a potential and attractive adsorbent for the decontamination of arsenic/chromium polluted water system.