Fig 1.
Cr(VI) removal performance by M-Fe and M-Fe/Cu with different Fe/Cu mass ratio (the initial concentration of Cr(VI): 20 mg/L, pH
= 7, T = 25oC).
Fig 2.
The XPS patterns of M-Fe/Cu-2: (a) Fe 2p and (b) Cu 2p.
Fig 3.
The effect of initial pH on the removal of Cr(VI) (a); the kobs and the removal efficiency at 2 h (b) (the initial concentration was 20 mg/L Cr(VI), T
= 25oC).
Fig 4.
The effect of initial Cr(VI) concentration for the Cr(VI) reduction: the removal efficiency at 2 h (a) and the kobs (b) (pH
= 7, T = 25oC).
Fig 5.
Cr 2p XPS analysis of M-Fe/Cu-2 after reaction for different time: (a) 5 min, (b) 15 min, (c) 60 min, (d) 90 min, (e) 180min, (f) 360 min.
Fig 6.
Fractions of Fe, Cu and Cr with different valence states in specific reaction time during the progress of Cr(VI) removal by M-Fe/Cu-2 according to the results of XPS spectra: (a) Fe, (b) Cu, (c) Cr.
Fig 7.
Fe 2p XPS analysis of M-Fe/Cu-2 after reaction for different time: (a) 5 min, (b) 15 min, (c) 60 min, (d) 90 min, (e) 180min, (f) 360 min.
Fig 8.
Cu 2p XPS analysis of M-Fe/Cu-2 after reaction for different time: (a) 5 min, (b) 15 min, (c) 60 min, (d) 90 min, (e) 180min, (f) 360 min.
Fig 9.
Schematic diagram of Cr(VI) removal by M-Fe/Cu-2.