Combined effect of weak magnetic fields and anions on arsenite sequestration by zerovalent iron

In this study, the effects of major anions (e.g., ClO4-, NO3-, Cl-, and SO42-) in water on the reactivity of zerovalent iron (ZVI) toward As(III) sequestration were evaluated with and without a weak magnetic field (WMF). Without WMF, ClO4- and NO3- had negligible influence on As(III) removal by ZVI but Cl- and SO42- could improve As(III) sequestration by ZVI. A synergetic effect of WMF and individual anion on improving As(III) removal by ZVI was observed for each of the investigated anion, which became more pronounced as the concentration of anion increased. The coupled influence of anions and WMF was associated with the simultaneous movement of anions with paramagnetic Fe2+ to keep local electroneutrality.