Adsorption Performance of Methyl Violet via α-Fe2O3@Porous Hollow Carbonaceous Microspheres and Its Effective Regeneration through a Fenton-Like Reaction

alpha-Fe2O3@porous hollow carbonaceous microspheres (alpha-Fe2O3@PHCMs) were prepared through a combination of hydrothermal and calcination method. The novel alpha-Fe2O3@PHCMs integrated the adsorptive and catalytic performances and served as an inexpensive adsorbent to rapidly remove cationic dye (methyl violet (MV)) from aqueous solution. Equilibrium studies indicated that the dye molecules obeyed Langmuir type of adsorption with the calculated maximum adsorption capacity of 539.8 mg.g(-1) at 313.15 K. Kinetic data were better described by pseudo-second-order model and the thermodynamic studies illustrated that MV adsorption onto the composite was spontaneous, endothermic and occurred by physisorption. The Fenton-like process was found to be effective for the regeneration of the spent alpha-Fe2O3@PHCMs. The regeneration efficiency, as high as 88.0%, was still maintained after three consecutive adsorption-regeneration cycles. FTIR and XRD characterizations of the composite before and after adsorption-regeneration treatment showed that the Fenton-like process did not cause serious damage to the structure of composites.