| Abstract: | This study explores the adsorption behavior of As(III) and As(V) on activated charcoal under the various conditions of solution pH and temperature. The adsorption loading of As(III) remains constant in the pH range from 0.16 to 3.5, while that of As(V) shows a maximum value at pH2.35 when the pH varies from 0.86 to 6.33. The isosteric heat of adsorption for As(III) varies from 4 to 0.75 Kcal/mole and that for As(V), from 4 to 2 Kcal/mole with varying surface loading. The magnitude of these values suggests that the adsorption of arsenic is by physisorption and due to weak forces such as Van der Waals forces. Activated charcoal adsorbs As(V) by 2.5% of its own weight while it absorbs As(III) by 1.2% of its own weight when the equilibrium concentration of each species is 22 × 10?2 molar. Since arsenic has appreciable adsorbability on activated charcoal, this adsorbent may be a viable candidate to be used for removing arsenic from solution. Further studies to determine more information on the selectivity of arsenic over other valuable metal ions and the ones to determine the effects of other cations such as, ferric, calcium, and magnesium ions are suggested as a next step. |
