Adsorption Characteristics of Aqueous Arsenic(III) and Arsenic(V) in Taiwan Soils

This study investigate the adsorption characteristics of aqueous arsenate [As(V)] and arsenite [As(III)] in Taiwan soils namely pinchen, chunliao and baiho. The results from the batch adsorption experiments showed that the adsorptive capability of the soils increased with increasing amounts of iron (Fe), manganese (Mn) and aluminum (Al) oxides. In the tested soils, the adsorption of As(V) was higher than that of As(III). The concentration of phosphate in tested soils negatively correlated with the adsorption of aqueous arsenic species As(V) and As(III). The desorption of arsenic occurred within 2-3 h after soils were submerged in water as evidenced by the increased concentration of As(V) and As(III) in the reaction systems. The kinetics analyses of the adsorption of As(III) and As(V) by the soils showed that the major part of reaction was of zero order, while minor part followed 3rd order reaction. This fundamental study will be helpful for further application in the treatment of arsenic contaminated Taiwan soils.