Fig. 1. (a) XRD patterns and (b) DSC curves of the Fe-based MG powders before and after reaction with AOII at initial pH.

Fig. 2. (a) UV-vis spectra of AOII solution treated with Fe-based MG powders, inset showing photographs of the AOII solution at different treating time. (b) Degradation efficiencies of AOII as a function of reaction time, inset showing the molecular structure of AOII.

Fig. 3. (a) Dependence of At normalized by A0 at different characteristic absorption peaks of AOII on reaction time. (b) UV-vis spectra of AOII in ethanol solution (0.004 g L-1) and UV-vis spectra of the supernatant ethanol washing the Fe-based MG powders after reacting with AOII for 5 min.

Fig. 4. SEM images of the original Fe-based MG powders: (a) overview and (b) enlarged view, inset showing the composition on the surface of the Fe-based MG powders. SEM images of the powders after reaction with AOII for (c) 5 min and (d) 10 min, insets showing the composition on the surface of the Fe-based MG powders after reacting with AOII for different time.

Fig. 5. Schematic illustration of the azo dye treatment by Fe-based MG powders.

Fig. 6. Degradation efficiencies as a function of time for (a) different cycles of the Fe-based MG powders and (b) different solution pH.