Zero-Valent Iron Nanoparticles Reduce Arsenites and Arsenates to As(0) Firmly Embedded in Core–Shell Superstructure: Challenging Strategy of Arsenic Treatment under Anoxic Conditions

Arsenites and arsenates are carcinogenic to humans and are typically removed from contaminated water using various sorbents. However, these treatment methods result in the secondary release of weakly bound As species and require large amounts of sorbents. Here, we introduce a groundbreaking method involving the use of oxidic-shell-free nanoscale zero-valent iron (OSF-nZVI) to treat arsenite/arsenate-polluted underground water. Under anoxic conditions, OSF-nZVI is capable to reduce As(III)/As(V) species to As(0) (up to 65% of total arsenic content). Thus, reduction synergistically contributes to sorption tuning suitably the chemical nature and isoelectric points of As species, thereby enhancing arsenic removal from an anoxic aqueous environment. More importantly, As species are locked between the Fe(0) core and iron(III) oxide outer shell. For comparison, the removal capability of OSF-nZVI is 2 times lower under oxic conditions, due to the complex redox mechanism resulting in exclusive sorption of As(III)/...