In Japan, scallop shells are considered to be industrial waste. Thus far, attempts for reusing these shells have been mainly limited to the commercial production of CaCO3. Nevertheless, there are no clear economic benefits associated with the use of scallop shells as a source of CaCO3. Hence, we are attempting to investigate a new value-added use for scallop shells as an advanced functional material. In this regard, we focused our attention on nuclear wastewater, which contains radioactive Sr and Cs. Sr, which tends to accumulate in bones, is believed to cause bone cancer. Hence, it is highly desirable to develop a method for removing Sr from contaminated water. In this study, we investigate whether scallop shells demonstrate the ability to remove Sr from a solution. From the results obtained, scallop shells can remove Sr solutes from a solution; furthermore, as compared to CaCO3, they demonstrate superior ability for removing Sr.

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It is important to efficiently remove radioactive substances contained in polluted waters before they are discharged from nuclear power plants. In particular, there is an urgent need for the development of technology that can adsorb radioactive Sr 2+ , but there are currently no inexpensive Sr 2+ adsorbents with low environmental burden. We found that scallop shell powder adsorbs Sr 2+ in aqueous solutions at various initial concentrations. In this study, to obtain fundamental knowledge of the mechanism of Sr 2+ removal using waste scallop shell, we analyzed the removability of Sr 2+ . Scallop shell showed the same capacity to remove Sr 2+ at a high initial concentration (²0.50 g/dm 3 ) as the reagent CaCO 3 , but a clear difference in removability appeared at a low initial concentration (0.010 g/dm 3 ), where scallop shell proved to be superior. In addition, scallop shell powder had slit-shaped pores and a specific surface area of 4.3 m 2 /g. Measurement of the adsorption isotherm in the low concentration aqueous solution showed that Sr 2+ removal occurred by chemisorption; the adsorbed Sr is present on the surface of the scallop shell powder particles.

Scallop shells become industrial waste every year in Japan. So far, attempts to reuse the shells have been mainly limited to the commercial production of CaCO3. There are no obvious economical benefits to using scallop shells as a source of CaCO3. Therefore, we are attempting to find a new value added use for scallop shells as an advanced functional material. The other background is nuclear wastewater, which contains radioactive Sr and Cs+. Sr tends to accumulate in bones and is believed to be a cause of bone cancer. Therefore, it is highly desirable to develop a method for the removal of Sr from the contaminated water.

No abstract