부산대학교 도서관

An easy method of separating protactinium from thorium by the use of the cation exchange resin, Dowex-50, has been discovered. The resin column adsorbed with 234Th (UX1) was treated with 12N HNO3 or 0.10.7 % oxalic acid for the elution of 234mPa (UX2). The decay curve of 234mPa is indicated in Fig. 1, and the elution curve is shown in Fig. 2. The tail portion of the elution curve in Fig. 2 is the milking of 234mPa from 234Th. Under these conditions, the 234Th adsorbed on top of the resin column showed practically no movement. By the use of the elution curve of 234mPa, approximate values of the distribution coefficient, Kd were calculated, and these values are shown in Tab. 1 and Tab. 2. From the relationship between the concentration of eluent and Kd ( Fig. 4), it is assumed that the Pa, in the case of using nitric acid as an eluent came out as a monovalent positive cation, PaO2+. On the other hand, it is assumed that using oxalic acid as an eluent caused the change of ionic state at the concentration of about 0.1 % oxalic acid, indicating the variation in the istructure of complex ion. By using this method, ia successful isolation of 234Pa (UZ), a nuclear somer of 234mPa (UX2), from 234Th (UX1) has been made (Fig. 3).