We developed an activated charcoal by creating bamboo charcoal that was carbonised at a temperature between 400 to 1000°C and then kept it at a temperature of 270°C for 2 h. One gram of activated charcoal was added to 100 mL of aqueous caesium of 2.67 × 10-2 mmol/L and 100 mL of strontium aqueous solution, and was stirred for 1 h. The caesium adsorption amount of bamboo charcoal, which was carbonised at 400°C, increased from 70.0% to 88.9%. In addition, the amount of strontium absorbed increased from 76.5%

The adsorption capacity of cesium and strontium in the aqueous solution of rice hull charcoal was examined. Rice husk which was carbonized at various temperatures was added to each of cesium aqueous solution and strontium aqueous solution and stirred. As a result, rice hull charcoal carbonized at 400°C adsorbed the cesium. Rice hull charcoal carbonized at 800°C adsorbed the strontium. From this result, it was considered that the adsorption mechanism of rice hull charcoal cesium and strontium are different. From the analysis results by FTIR and Boehm method, charcoal carbonized at 400°C had acidic functional group. There was a tendency that the pH of the rice hull charcoal carbonized at high temperature became higher. It is considered to be due to precipitation of inorganic substances such as potassium on the surface of rice hull charcoal. As a result of pore distribution measurement, it was found that many mesopores were formed in rice hull charcoal carbonized at 800°C. It is assumed that cesium adsorbs primarily on acidic functional groups on the surface of rice hull charcoal, strontium undergoes ion exchange with potassium, or adsorbs to mesopores.

The adsorption capacity of rice hull charcoal for cesium and strontium in aqueous solution was examined. Rice husk carbonized at various temperatures was added to aqueous solutions of cesium and strontium and stirred, whereupon, samples carbonized at 400°C adsorbed cesium, and those carbonized at 800°C adsorbed strontium. In view of this result, it was inferred that the mechanisms of adsorption of cesium and strontium on rice hull charcoal are different. FTIR analysis and Boehm titration results indicated that charcoal carbonized at 400°C had acidic functional groups. In addition, the pH of the rice hull charcoal carbonized at high temperature tended to be higher, which is attributed to precipitation of inorganic substances such as potassium on the surface of rice hull charcoal. Pore distribution measurements showed that many mesopores were formed in rice hull charcoal carbonized at 800°C. It was concluded that cesium adsorbs primarily on acidic functional groups on the surface of rice hull charcoal and strontium undergoes ion exchange with potassium, or adsorbs on mesopores.

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