Hydrous ferric oxide as an adsorbent in water treatment: Part 2. Adsorption studies

The mechanism of arsenic adsorption onto hydrous granular ferric oxide is discussed in detail. The effect of arsenic speciation and complexation with the granular ferric hydroxide surface is discussed in relation to batch equilibration studies. Despite the complex nature of the binding mechanism, a Langmuir model provided a satisfactory fit of the data. Mini-column experiments have shown the effective sorption of arsenic from water in the pH range 7–8 and confirmed efficient elution using dilute mineral acid. Granular ferric hydroxide can be used for the removal of trace As(V) from water, eluted and recycled and moreover, the release of iron from the adsorbent was found to be negligible under appropriate operating conditions.