Enhancing the Regeneration Performance of Methylene Blue Saturated Biochar in H2O2 System via Fe-Doping

To improve the regeneration efficiency of methylene blue (MB) saturated biochar in H2O2 system, biochar was modified by Fe-doped by using FeSO4 and Fe(NO3)(3) as iron sources. The effects of Fe-doped on its microstructure were characterized by XRD, SEM, and BET. The adsorption and regeneration performance of biochar before and after Fe-doped were compared through adsorption and regeneration experiments. X-ray photoelectron spectroscopy, electron spin resonance, and quenching experiments were used to explore the regeneration mechanism. The results show that Fe-doped biochar (SP-GBC) prepared from FeSO4 maintains a high specific surface area of 1205.9 m(2)/g and a high adsorption capacity of 375.43 mg<middle dot>g(-1) for MB. After adsorption, the MB-saturated SP-GBC exhibits excellent regeneration performance in the H2O2 system, in which the regeneration efficiencies for five consecutive cycles are 85.76%, 83.92%, 94.01%, 99.24%, and 100.79%, respectively. The synergistic effect of H2O2 desorption and degradation is the main regeneration mechanism for MB-saturated SP-GBC. The zero valent iron and Fe (II) on the surface of SP-GBC are the main active sites for H2O2 activation, while O-1(2) and HO<middle dot> are the main oxidation species. In summary, this work provides a simple and feasible method for the design and synthesis of adsorbents with highly efficient regeneration performance.