BACKGROUND: Cr(VI) is being increasingly used in a variety of fields, including electroplating, metallurgy, pigments synthesis and leather tanning. Possible application of microbial extracellular polymeric substance (EPS) from Klebsiella sp. J1 with abundant functional groups to remediate Cr(VI) pollution in water system was demonstrated.

RESULTS: The maximum biosorption capacity of EPS for Cr(VI) was found to be 53.3 mg/g at EPS dose of 1.5 g/L, which was better than the majority of reported biosorbents. The adsorption of EPS for Cr(VI) was spontaneous and endothermic process. The removal mechanism of Cr(VI) in aquatic environment was qualitatively and quantitatively explored by Zeta‐potential meter, X‐ray photoelectron spectrometer (XPS) as well as FTIR spectrometer. The superior Cr(VI) removal performance was mainly attributed to the Cr(VI) adsorption on EPS via chelation and ion‐exchange sorption, and the efficient reduction (82.3%) of Cr(VI) to Cr(III) by benzenoid amine (–NH–) on EPS, followed by generated Cr(III) immobilization on the surface of EPS via surface physical sorption and chelation, which might control the reaction rate of Cr(VI) removal process.

CONCLUSION: The Cr(VI) removal by EPS from Klebsiella sp. J1 was mainly attributed to simultaneous sorption and reduction of Cr(VI) by EPS. The results demonstrated the EPS from Klebsiella sp. J1 have great potential in treating Cr(VI)‐contaminated water.