Mechanism of As(V) Removal in Wastewater Treatment Using Fe(III)-Supported Exchange Resins

Abstract

As(V) removal mechanism using Fe(III)-supported ion exchange resins was elucidated by adsorption isotherms and X-ray absorption fine structure spectroscopy. Fe(III) substituted almost all counter ions in the resin at pH 2 during 1-h reaction; the Langmuir exchange capacity was 1.87 mmol Fe/g-resin. The Fe(III)-supported resin comprised ≈65% Fe(III) and ≈35% ferrihydrite. Under pH 3 and arsenic concentration of 10 mg/dm 3 conditions, a sorption density of 0.035 mmol As/g-resin was obtained after 1-h reaction, and increased to 0.74 mmol As/g-resin after 120-h reaction. As(V) removal proceeded mainly via surface precipitation of poorly crystalline ferric arsenate via co-precipitation between As(V) and Fe(III); also, some As(V) adsorbed on ferrihydrite.