Magnetic nanocomposite microbial extracellular polymeric substances@Fe3O4 supported nZVI for Sb(V) reduction and adsorption under aerobic and anaerobic conditions

The extracellular polymeric substances coating magnetic powders-supported nano zero-valent iron (nZVI@EPS@Fe3O4) was synthesized, using reduction and adsorption to treat Sb(V) wastewater. The adsorption performance and mechanism were investigated under aerobic and anaerobic conditions. The adsorption capacity of nZVI@EPS@Fe3O4 (79.56 mg/g at pH = 5) was improved compared to that of the original materials (60.74 mg/g). The spectral analysis shows that both nZVI and EPS@Fe3O4 in nZVI@EPS@Fe3O4 played an important role in reducing Sb(V) to Sb(III) and adsorbing Sb. The reducibility and adsorption capacity of nZVI@EPS@Fe3O4 towards Sb(V) remained strong under aerobic condition (62% Sb(III), 79.56 mg/g), although they were slightly weaker than those under anaerobic condition (74% Sb(III), 91.78 mg/g). nZVI@EPS@Fe3O4 showed good performance in regeneration experiments. nZVI@EPS@Fe3O4 is promising as a cost-effective and highly efficient material for Sb(V)-contaminated water. This study is meaningful in understanding the redox behaviour of nZVI composites in aerobic and anaerobic conditions.