Under anoxic conditions, this study investigated removal of dissolved As(III) by Si and Al oxides including natural sand, chemically washed sand (silica), alumina, and activated alumina. Despite the similar surface area, natural sand showed greater extents of As(III) sorption than chemically washed sand. This was likely due to the high reactivity of Fe(oxyhydr)oxide impurities on the surface of natural sand. For both sands, As(III) sorption was the greatest at pH 7.1, in agreement with the weakly dissociating tendency of arsenous acid. Also, the least sorption was observed at pH 9.6. At basic pH, elevated silicate, which originated from the dissolution of silica in sands, would compete with As(III) for sorption. Due to the highest surface area, activated alumina was found to quantitatively immobilize the initially added As(III) (6.0×10−7 -2.0×10−5 M). Alumina showed As(III) sorption compared to or greater than chemically washed sand, although the former had less than 6% of the surface of area the latter. The greater reactivity of alumina than chemically washed sand can be explained by using the shared charge of oxygen.

Abstract
Introduction
Materials and Methods
Results and Discussion
Conclusions
Acknowledgment
References

• Seungyeol Lee(Department of Geological Sciences, BK21 School of Earth and Environmental Systems, Pusan National University,NASA Johnson Space Center & Lunar and Planetary Institute, Houston)
• Minji Park(Department of Geological Sciences, BK21 School of Earth and Environmental Systems, Pusan National University, Busan 46241, South Korea)
• Hoon Young Jeong(Department of Geological Sciences, BK21 School of Earth and Environmental Systems, Pusan National University, Busan 46241, South Korea) Corresponding author