Scintillating polymer inclusion membrane for preconcentration and determination of (alpha)-emitting actinides

The scintillating polymer inclusion membrane (S-PIM) was developed for preconcentration and determination of (alpha)-emitting actinides from aqueous solution. The preparation of S-PIM involved physical immobilization of an extractant bis(2-ethylhexyl)phosphoric acid, primary scintillator 2,5-diphenyloxazole, and secondary scintillator 1,4-bis(2-methylstyryl)benzene in the plasticized cellulose triacetate matrix. The S-PIM was found to be effective for the quantitative sorption (94–98%) of trivalent lanthanides/actinides (147Pm, 154Eu and 241Am), tetravalent actinides (Pu(IV)) and hexavalent actinides (U(VI)) from the aqueous solutions whose acidity had been adjusted to pH 2.5, 1.0 and 0.25 mol/L, respectively with dilute HNO3. The interference of (beta)-emitting lanthanides, in preconcentration and determination of (alpha)-emitting actinides using S-PIM, were also studied. The (alpha)-scintillation counting efficiency in the S-PIM was found to be 92–95% after discriminating the background noise. However, (beta)-scintillation counting efficiency was found to be in the range of 12–25% depending upon the energy of (beta)-particles. It was observed that (beta)-scintillation pulses from 147Pm and 154Eu could be discriminated based on pulse height analysis. Thus, (alpha)-activities of the actinides sorbed in the sample of S-PIM could be directly measured in the presence of (beta)-emitters by scintillation counting. However, the (alpha)-scintillation counting efficiency was reduced to 38% after discriminating (beta)-scintillation pulses in the S-PIM. The preconcentration ability of S-PIM was examined in tap water and seawater spiked with 241Am. The total (alpha)-activity of 46 Bq (present in 100 mL) could be preconcentrated and measured from tap water using SPIM.