Fig. 6: The characterization of EW-BC before and after Cr(VI) removal.

a The FTIR spectra of EW-BC before and after Cr(VI) removal. b The XRD spectra of EW-BC after Cr(VI) removal. c The XPS spectra of EW-BC before and after Cr(VI) removal. d The Cr2p spectra of EW-BC after Cr(VI) removal.