Performances of purified indigenous Leifsonia sp. and its mechanism in the removal of Cr(VI) under shaking condition

Abstract

The increasing discharge of wastewater with chromium(VI) plays adverse impacts on the environment in recent years. This study purposes to investigate the adsorption efficiency and removal mechanism of chromium(VI) via a purified indigenous bacteria (Leifsonia sp.). The effect of varying pH, initial chromium(VI) concentration, dosage of dry biosorbent, contact time and temperature on the adsorption efficiency of chromium(VI) was studied via single-factor experiment. Our results demonstrate that the strain has high efficiency of adsorbing chromium(VI) from aqueous solution. The maximum removal rate of chromium(VI) was 95.4% when pH was 2 (range 1.5–9.0), contact time was 4 h, the initial chromium(VI) concentration was 10 mg/L and the temperature was 30 °C (10–50 °C). Freundlich isotherms fit the adsorption process well, and the adsorption kinetics is consistent with the pseudo-secondary kinetic model. Furthermore, the adsorption mechanism was elucidated via FTIR and XPS, indicating that chromium precipitates on the biosorbent surfaces are a mixture of chromium(VI) and chromium(III). It is implied that physisorption and chemisorption proceed at the same time during the chromium(VI) adsorption process. These findings show that Leifsonia sp. as a biosorbent displays excellent adsorption efficiency, having the potential to remove chromium(VI) from aqueous solutions.