Removal of Iron from Water Using Adsorbent Carbon

Abstract

A novel adsorbent carbon to remove iron from water was evaluated. Bench scale and pilot scale tests were performed to characterize the mechanism of the iron removal. The adsorption equilibrium of iron removal can be described using the Langmuir isotherm, assuming a monolayer. In the absence of dissolved oxygen, Fe2+ is adsorbed on the solid surface as a monolayer of 62.7 × 10−3 mat‐g·g−1, while the monolayer of oxidized iron coverage in the air‐equilibrated system is 72.7 × 10−3 mat‐g·g−1. The iron removal results from the adsorption of oxygen followed by the oxidation of Fe2+ catalyzed by the adsorbent carbon surface. The Fe3+ precipitates on the solid, forming a hydrated iron oxide‐coated carbon that is also able to adsorb iron. The kinetics of iron removal was modeled using the film and pore diffusion model. Pilot tests performed with and without pre‐aeration showed results similar to those observed on the bench scale.