抄録
The aim of this study was to develop a new type of adsorbent that can sink to the bottom of a body of water, adsorb pollutants there, and then float up on the surface of water to be collected easily. The purpose could be achieved by controlling the specific gravity of alginate gel beads by adding CO2 gas bubbles as a float and calcium carbonate (CaCO3) salts as a weight, and by the dissolution of the CaCO3 in the gel beads. The floating time of the alginate gel beads, which is a time necessary to float up on the surface of water after adding them to water, depended on the amount of salts and the amount and size of bubbles in the beads. When alginate gel beads containing 5 wt% of CaCO3 were added to the solution of pH 3.0, the beads sank to the bottom of water and then floated up to the surface of the water after a delay of about 150 minutes. The floating time of the alginate gel beads increased almost linearly with increases in the amount of CaCO3 in the bead. After the repeated additions of the alginate gel beads containing 3 wt% of CO2 bubble and 5 wt% of CaCO3, 98.4 wt% of total lead ions in the bottom of water could be removed. CaCO3 added in the alginate gel bead also acted as a reagent to keep the pH of the inside of the bead basic. Therefore, even in the acidic solution, the gel beads showed the adsorption ability for lead ions.
