Paper Simultaneous removal of antimony(III/V) and arsenic(III/V) from aqueous solution by bacteria-mediated kaolin@Fe-Mn binary (hydr) oxides composites

Antimony (Sb) and arsenic (As) pollution in aquatic ecosystems has received great attention owing to their environmental toxicity and health risk. In this work, a green kaolin@Fe-Mn binary (hydr)oxides composites (BKFMs) synthesized by iron oxidizing bacteria (IOB) mediation was developed to simultaneously remove Sb and As. The prepared BKFMs possessed large specific surface area and pore volume, as well as abundant functional groups, which contributed to eliminate Sb and As. Among prepared composites, BKFM (1:0.1) exhibited the best Sb and As removal performance, and the kinetics data of Sb(III/V) and As(III/V) by BKFM (1:0.1) conformed to the pseudo-second-order kinetic and Elovich models. Moreover, the isotherm experimental results indicated that the maximum BKFM (1:0.1) adsorption capacities for Sb(III), Sb(V), As(III) and As(V) were 177.19, 56.26, 62.92 and 42.18 mg/g, respectively (pH = 6.0 +/- 0.1, T = 25 C). In addition, the solution pH and co-existing substances had varying effects on Sb(III/V) and As(III/V) adsorption. Characterization techniques of FTIR and XPS revealed that the inner-sphere complexation, surface complexation, hydrogen bonding and oxidation contributed to the mechanism of adsorption of Sb and As. The results demonstrated that BKFM (1:0.1) has great potential for future application in Sb and As removal from contaminated water.