Ferrate(VI) pretreatment of water containing natural organic matter, bromide, and iodide: A potential strategy to control soluble lead release from PbO(s).

Lead dioxide (PbO(s)) is a corrosion product of lead-containing plumbing materials in water distribution pipelines. The presence of reductants in water could cause the release of soluble lead (mainly Pb(II)) from PbO(s). Lead in drinking water is detrimental to public health. This paper presents the first application of ferrate (FeO, Fe(VI)) to decreasing the generation of soluble lead in water containing PbO(s) and common reducing constituents (e.g., natural organic matter (NOM), iodide (I), and bromide (Br)) at different pH conditions (i.e., 6.0, 7.0, and 8.0). The released soluble lead from PbO(s) was found to be dominantly controlled by NOM in water, via the redox dissolution of PbO(s) and the reduction of PbO(s) by reducing moieties of NOM. The feasibility of both processes increased when pH decreased. The I and Br in water played minor roles in generating soluble lead. Fe(VI) reacted with reducing functional groups of NOM, as determined by C nuclear magnetic resonance spectroscopy. Water pretreatment with Fe(VI) inhibited the reaction of NOM with PbO(s) and therefore, caused lower soluble lead concentrations compared to water samples without Fe(VI) treatment. This study indicates that Fe(VI) pretreatment is a potential approach to controlling soluble lead in drinking water.