Presentation on theme: "Analysis of Actinide Elements from Large Environmental Samples"— Presentation transcript:
1Analysis of Actinide Elements from Large Environmental Samples Guebuem KimBill BurnettFlorida State UniversityandE. Philip HorwitzPG Research Foundation, Inc.
2Need for Large Volumes Achieve low MDA's for environmental monitoring Specialized scientific studies often require large volumes to obtain necessary sensitivity, e.g., Am/Pu in seawater, global fallout in recent soils
3Analytical Challenges Preconcentration of actinides from natural water samples may require handling up to litersLarge (5-10 grams or more) soil/sediment samples may require difficult and lengthy dissolution proceduresSeparation chemistry, especially from large soil/sediment samples, suffers from “matrix effects.”
6Am/Pu from 200-L SeawaterSupernatant seawater transferred from one plastic tank to another via pumping — this will be used for 90Sr and 137Cs.MnO2 suspension withdrawn from bottom of conical-shaped plastic tanks — processed for Am and Pu.
15HEDPA Destruction via Ozone 20-mL elution was diluted to 70 mL, H2O2 added (0.5M), pH adjusted to 9.0 with NaOH, and samples ozonated for variable lengths of time
16Ozonation ProcesssampleOzone delivered from an ozone generator via a gas diffusion stone oxidizes the HEDPA
17Oxidation by Fenton’s Reagent finishedTreatment:40 mL 0.5M HEDPA + 1 mL HNO mL H2O g Fe(NH4)2(SO4)2·6H2OTemperature ~90oCH2O2 + Fe2+ ® OH + OH- +Fe3+
18Final clean-ups: Am/Ln on TEVA; U on UTEVA Actinide SeparationsSample(3M HNO3, 0.7M Al(NO3)3, FS, AA)TRUResin1234562.5M HNO32.5M HNO3/0.1M NaNO29M HCl4M HCl4M HCl/TiCl31M HCl0.1M Ammonium BioxalateDiscardAmPuThUTRU·Resin tolerates high PO4Final clean-ups: Am/Ln on TEVA; U on UTEVA
20Preliminary TestsAm-241 and Th-234 spiked samples. Matrix = HNO3/HCl leach of 10-g NIST Rocky Flats II soil
21Standard Samples: Yields Samples (n=7):3 EML soils2 IAEA sediments2 Fe-rich soils5 intercomparison samples and 2 Fe-rich samples run through entire procedure and analyzed for Am, Pu, U, and Th. 10-gram samples were leached with HNO3/HCl.
22Standard Samples: Results Table 1: EML and IAEA intercomparison values.
23SummaryUptake of actinides onto Diphonix from complex matrices is very efficient0.5M HEDPA easily elutes actinides“Fenton’s Reagent” or O3 successfully oxidizes HEDPASeparations starting with TRU·Resin prevent PO4 interference