The removal of arsenic (As) from drinking water is an important environmental challenge that requires efficient sorbents and filter materials. Arsenic's predominant oxidation state and acid/base chemistry play important roles for remediation techniques in groundwater and environmental sources. Based on previous investigations the removal of arsenite (As(III)) and arsenate (As(V)) by zerovalent iron (Fe(0)) is achieved by coupling with Fe(0) oxidation/corrosion that forms particle surface films composed of amorphous Fe(III) oxide/hydroxide plus magnetite (Fe3O4). In this study we investigated the reactions of As(III) and As(V) with commercial Fe3O4 and multiple sources of Fe(0) remediation materials including 100-mesh Fe(0) powder and Fe(0) nanoparticle slurry. Batch As(III)/(V) experiments were performed to create adsorption isotherms and envelopes on these materials. Analysis of total dissolved As was performed with a microwave plasma-atomic emission spectrometer (MP-AES). Solid corrosion products were investigated with X-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM). Commercial Fe3O4 showed relatively weak overall As adsorption compared with Fe(0). The As(V) species showed a maximum uptake of 0.10 mg As(V)/g solid at low pH while As(III) adsorption was favored at neutral to alkaline pH levels on Fe3O4. These results, together with detailed XRD results of Fe(0) corrosion products, suggest that in-situ Fe(0) corrosion reactions that form Fe(III) oxide/hydroxide films on reacting Fe(0) particle surfaces are primarily responsible for the high total As removal by Fe(0). This supports previous investigations showing that Fe(0) surface corrosion reactions that form high surface area Fe(III) oxide/hydroxide solids contribute to an efficient mechanism As(III)/As(V) removal mechanism.

Adsorption of arsenic on magnetite and zero-valent iron corrosion products

248th National Meeting (2014)

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