EFFECTS OF SILICIC ACID ON ENVIRONMENTAL STABILITY OF SPENT MAGNESIUM-BASED ARSENIC ADSORBENTS

Abstract

 The adsorbents which removed arsenic from contaminated water would contain a large amount of arsenic. If the spent adsorbents were dumped into environment without an appropriate treatment, a secondary environmental pollution might be caused by arsenic leaching.
 In this study, the leaching tests with silicic acid solution on the spent magnesium-based adsorbents (MgO, Mg(OH)₂ and two types of MgCO₃) were conducted and the experimental data obtained were examined. From the results, the spent Mg(OH)₂-based and MgCO₃-based adsorbents were found to leached arsenic more easily as silicic acid concentration in liquid is higher. On the other hand, the spent MgO-based adsorbent was found to leach little arsenic and maintain extremely high environmental stability. Therefore, MgO among them was concluded to be the most excellent arsenic adsorbent to be used under the conditions where silicic acid is generated in the leachates from soils, cement-based solidifying materials and so on.