Facile preparation of novel magnetic mesoporous Fe Mn binary oxides from Mn encapsulated carboxymethyl cellulose-Fe(III) hydrogel for antimony removal from water

Effective removal of Sb(III) and Sb(V) has long been an urgent task for protecting human health and environment. In this study, novel magnetic mesoporous FeMn binary oxides (MMFMs) were fabricated via calcinating the Mn encapsulated carboxymethyl cellulose-Fe(III) hydrogel, and the structure of MMFMs were closely related to the Fe:Mn ratio. Owing to the mesoporous structure together with synergistic effect of FeMn binary component, the MMFMs exhibited excellent mass transfer and adsorption ability to Sb(III) and Sb(V). MMFM3 achieved a maximum Sb(III) and Sb(V) adsorption capacity of 281.5 and 204.6 mg/g, respectively. Co-existing anions of Cl-, NO3- and SO42- exhibited marginal influence on the adsorption for both Sb(III) and Sb(V), except the PO43- for Sb(III) and SiO32- or PO43- for Sb(V). X-ray photoelectron spectroscopic investigation revealed that high valence Mn(IV) was mainly responsible for the oxidation transformation of the highly toxic Sb(III) into less toxic Sb(V), while the FeOx content played major role for the adsorption of Sb(V). The generated inner-sphere FeOSb complex between Fe-OH groups and Sb(III/V) dominantly contributed to the removal of Sb(III/V). Overall, mesoporous structure, magnetic separation ability, excellent adsorption performance together with exceptional regeneration properties demonstrated the great potential of MMFMs for Sb(III/V) remediation.