アポフィライトから調製した層状アルミノシリカのメチレンブルー吸着

抄録

The specific layered silica hydrate and alumino-silica hydrate can be prepared from apophyllite has been reported. In this study, three samples were prepared from apopohyllite and examined their cation adsorption properties with methylene blue molecules as a probe. The samples were prepared in two ways; natural apophyllite was (1) treated with hydrochloric acid at 5°C and (2) treated with aluminum chloride solution at room temperature. Two alumino-silica samples were prepared by varying the concentration of the reaction solution. As a result, these alumino-silica samples had different Al/Si ratio from each other.
For the silica sample, it is found that the amount of adsorbed methylene blue molecules increased with increasing pH value of the solution. This tendency suggested that methylene blue adsorption was due to broken bond covalence of silica samples. In the case of the alumino-silica samples, amount of adsorbed methylene blue were seemed to be independent of pH value of the solution. This result indicated that negative charges of the almino-silica sheets did not change in these conditions. Therefore, it suggested that aluminum atoms forming the frameworks were mainly attributed to methylene blue adsorption. According to the X-ray diffraction patterns, methylene blue molecules could not be introduced between the slilca-sheets of the samples. Since the internal surfaces are not available to the adsorption ofmethylene blue, the amounts of adsorbed methylene blue molecules are much smaller than that of the other clay minerals.
UV spectra of methylene blue on all samples showed that some of methylene blue molecules formed dimer and trimer on the surfaces of the samples.