Natural Hazards and Disaster Management

Biography

Biography: Young-Soo Han

Abstract

This study examined the reaction mechanism of antimonate Sb(III) uptake in iron monosulfide mackinawite and compared its removal capacity and pH-dependent uptake behavior with that of As(III). The comparison of Sb(III) with As(III), based on their chemical similarity, may give useful insight into the chemical properties of the less studied Sb(III). Batch sorption studies revealed that Sb(III) had a higher affinity for mackinawite at pH 5 than pH 7 or 9. While As(III) displayed a similar trend, there was a much higher uptake of Sb(III) under all three pH conditions. A spectroscopic study demonstrated the high uptake of Sb(III) at pH 5 was due to precipitation of the sulfide mineral Sb₂S₃ as a consequence of the mackinawite dissolution while the removal at pH 7 or 9 was inferred as a surface reaction possibly a sole or mixed reactions of adsorption and surface-precipitation. These pH-dependent Sb(III) uptake mechanisms are similar to the corresponding mechanisms for As(III) uptake, demonstrating that mackinawite is also a good scavenger for Sb(III) in ferrous and sulfide-rich reducing environment like for As(III).

Image

Figure 1: As(III) and Sb(III) removal efficiency under pH 2 to 12 with the amount of dissolved As or Sb left in solution with its speciation (I₀ = 150 mg/L for As(III) and 500 mg/L for Sb(III)). Aqueous speciation was conducted using Bond Elut C18 cartridge