ADSORPTION BEHAVIOR OF FULVIC ACID, COPPER, AND THEIR COMPLEX ONTO CLAY MINERALS

摘要

In Japanese landfill sites, municipal solid waste incineration residues (MSWIR) were mainly disposed. Although incineration reduce can reduce the volume of waste materials, many pollutants, especially heavy metals, were accumulated in MSWIR. That's why the leachates from landfdl sites were monitored and treated to evaluate the stabilization of the landfill sites even after the disposal was finished. However, it is difficult to evaluate the stabilization of heavy metals because the behaviors of heavy metals were complex such as adsorption to the organic compounds. Therefore, the long term behaviors of heavy metals in landfill site could not be explained with the scientific basis. For this reason, it is quite difficult to estimate necessary period for complete closure of a landfill site. On the other hand, as immobilization mechanisms of heavy metals in landfdl sites, it is well known like precipitations (CO3~(2-), S~(2-), SO4~(2-)) , adsorption to some materials (iron hydroxide, aluminum hydroxide, clay minerals). Furthermore, in the field of water environment, it is reported that humic substance was greatly related to the mobilization and accumulation of heavy metals especially copper, lead, zinc. This function of humic substances was expected as well as landfill site. In particular, it is well known that the mobilization of copper depends strongly on the complexation with dissolved organic matter (DOM) in natural environment. According to Van Zomeren et al, 82 to 100 % of copper in the leachate of landfilled MSWI bottom ash was bound by DOM including humic substances between pH 6.6 and 10.6. Therefore, in this study, copper was focused on because copper mobility in a landfdl body might strong relation with humic substance. In previous study, it was proved that the non-ideal competitive adsorption-Donnan (NICA-Donnan) model could describe the interaction between copper and fulvic acid in liquid phase. However, it was not researched so much about the behavior of copper after complexation with fulvic acid. So, the objective of this study was to investigate the adsorption behavior of copper, fulvic acid, and their complex onto clay minerals.