Effective removal of Sb(V) from aqueous solutions by electrocoagulation with composite scrap iron-manganese as an anode.

Improving the removal rate of pentavalent antimony (Sb(V)) by electrocoagulation (EC) is of great significance to the environment. In this paper, the EC with composite scrap iron and manganese filings as an anode (Fe-Mn EC) was investigated for the high-efficiency elimination of Sb(V). The results showed that Fe-Mn EC can enhance the removal of Sb(V) by 11.18-17.36% compared with the traditional iron electrocoagulation (Fe EC). Meanwhile, Sb(V) removal increased with the growth of current concentration as well as Mn content in the anode. However, the Sb(V) removal rate was inhibited when Mn content exceeded 20%. Moreover, the flocs generated during the Fe and Fe-Mn EC (Fe flocs and Fe-Mn flocs) were analyzed both structurally and theoretically using XRD, SEM, BET, and adsorption experiment. The results indicated that the components of Fe-Mn flocs were mostly Mn-substituted FeOOH, which appeared as the structure of nanometer flakes and large internal surface areas. Meanwhile, the Fe-Mn flocs had the ability of much faster Sb(V) adsorption rate; its Sb(V) adsorption capacity was 2.5 times more than that of the Fe flocs. The thermodynamics constants of both Fe and Fe-Mn flocs proved that adsorption was associated with monolayer physical adsorption. To the best of our knowledge, this is the first report of the electrocoagulation with composite scrap iron-manganese as an anode to remove Sb, which provide a new idea and potential technical support for the removal of Sb(V).