Synthesis of nano-silica and biogenic iron (oxyhydr)oxides composites mediated by iron oxidizing bacteria to remove antimonite and antimonate from aqueous solution: Performance and mechanisms

Removal of antimony from wastewater is essential because of its potential harm to the environment and human health. Nano-silica and biogenic iron (oxyhydr)oxides composites (BS-Fe) were prepared by iron oxidizing bacteria (IOB) mediation and the batch adsorption experiments were applied to investigate antimonite (Sb(III)) and antimonate (Sb(V)) removal behaviors. By contrast, the synthetic BS-Fe calcined at 400. (BS-Fe-400) exhibited a large specific surface area (157.353 m(2)/g). The maximum adsorption capacities of BS-Fe-400 were 102.10 and 337.31 mg/g for Sb(III) and Sb(V), respectively, and experimental data fit well to the Langmuir isotherm and Temkin models, and followed the pseudo-second order kinetic model. Additionally, increasing pH promoted Sb(III) adsorption, while inhibited the adsorption of Sb(V), indicating that electrostatic attraction made a contribution to Sb(V) adsorption. Moreover, different co-existing ions showed different effects on adsorption. Characterization techniques of FTIR and XPS indicated that the main functional groups involved in the adsorption were -OH, C-O, C=O, C-C, etc. and Sb(III) and Sb(V) may bind to iron (oxyhydr)oxides via the formation of inner-sphere complexes. The present work revealed that the synthetic BS-Fe-400 by nano-silica and biogenic iron (oxyhydr)oxides held great application potential in antimony removal from wastewater.

Automated summary

The study investigated the efficiency of nano-silica and biogenic iron (oxyhydr)oxides composites in removing antimony from wastewater, showing a high adsorption capacity for both Sb(III) and Sb(V), demonstrating the potential application of the synthetic material in antimony removal.