S Stephen, AE Pillay, T Shah and E Siores
Keywords: ICP-MS, isotopic fractionation, Ti-46/Ti48, polypropylene
Abstract: Fractionation effects associated with heavy metal isotopes leached from a doped polypropylene matrix was studied. The matrix itself was doped with oxides of Mg, Ti and Zn at levels of 3% and 10%. Acid leaching was investigated at pH3 and pH10. The leachates were analyzed by high performance ICP-MS and the results showed that normal natural abundances were recorded for Mg and Zn. However, depletion of Ti-48 and enrichment of Ti-46 were observed at statistically significant levels. At pH3, Ti-46 and Ti-48 displayed cycles of decay and growth with leaching over time for both the 3% and 10% doped polymeric materials. Such growth and decay were less pronounced for pH10, but the existence of enriched and depleted levels persisted. These data are interpreted in terms of the extraordinary crystal structure of TiO2, and mechanisms relating to the crystal lattice arrangement of TiO2. The mechanistic aspects were corroborated by TEM imaging. The fundamental application of our work lies in the discovery of a facile process for preparation of enriched Ti-46 solutions and depleted Ti-46 polymers.
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