Metal ion-induced enhanced oxidation of organic contaminants by ferrate: a review

The global contamination of water resources by organic contaminants such as pharmaceuticals and pesticides is calling for advanced remediation techniques, yet conventional water treatments are incomplete or generate toxic byproducts such as chlorinated compounds. As a consequence, safer methods such as treatment with ferrate are needed. Here, we review the utilization of ferrate(VI), the tetraoxy anion FeO₄²⁻, with emphasis on synthesis and activation of ferrate. Ferrate synthesis is done by wet, thermal, and electrochemical processes. An increase in the oxidation capacity can be obtained by activation of ferrate(VI), which generates highly reactive high-valent iron species such as iron(V) and iron(IV) species. We present activation of ferrate(VI) by iron(III), copper(II), and colloidal Mn(IV), which are present in natural minerals. We compare various ferrate(VI)–metal ion systems to reveal the most effective systems to remove organic contaminants from contaminated water.