IRON(III) HYDROXIDE-LOADED CORAL LIMESTONE AS AN ADSORBENT FOR ARSENIC(III) AND ARSENIC(V)

Trace levels of As(III) and As(V) in aqueous media were effectively adsorbed onto a coral limestone loaded by Fe(OH)3. The adsorption of As(III) was almost comparable to that of As(V). The adsorption of As(III) and As(V) was almost independent of the pH of the aqueous phase (pH range: 3-10) because of a self-buffering effect of the coral. The addition of such anions as chloride, nitrate, sulfate, and acetate in the aqueous phase did not significantly affect the adsorption of As(III), whereas the addition of phosphate brought about a great decrease in the adsorption. The arsenic adsorption was effectively applied to the column method. Unloaded coral itself was effective as an adsorbent for As(V) when Fe(III) coexisted in the aqueous solutions.