Laboratory Report on the Reduction and Stabilization (Immobilization) of Pertechnetate to Technetium Dioxide Using Tin(ii)apatite

The function of Sn(II)-apatite as a Tc immobilizing agent

“…From microwave digestion and subsequent analysis with inductively coupled plasma optical emission spectroscopy (ICP-OES), the Sn-A was found to contain 25.0 wt% Ca, 14.4 wt% P and 23.5 wt% Sn, with the remainder comprised of O (29.8 wt% O if all assumed to be with P as PO4) and supporting anions. Sn-A has previously been reported to be an amorphous pattern with only a weak crystalline hydroxyapatite peak appearing, see Appendix B of Qafoku et al [22,24]Without supporting anion identification, the exact formula of Sn-A cannot be determined.…”

“…The Sn-A was prepared by an outside laboratory following a previously reported method. [22,23] Sn-A prepared with this synthetic method has been reported to be comprised of an apatite (Cax(PO4)y(X)) structure with partial substitution of Ca(II) by Sn(II) in the lattice. [23] The exact chemical content of the supplied materials was determined using microwave digestion (per U.S. EPA Method 3051A, Revision 1 2007) and the moisture content was determined gravimetrically (per ASTM D2216).…”

“…It should be noted that differences in Ca and P concentations could not be successfully measured in the LAW simulant solution due to the initial high concentrations in solution. As pH increased, more Sn is lost from the Sn-A solid, which could account for the decrease in performance toward Tc removal at increasing pH [22]. The initial batch experiments performed in LAW simulant were conducted at a ratio of 1 g : 100 mL.…”

Updated Liquid Secondary Waste Grout Formulation and Preliminary Waste Form Qualification

“…The pellets were crushed with a mortar and pestle to a size < 300 µm before use. Snapatite was prepared by the RJ Lee group (Richland, WA) according to a previously published method (Duncan et al 2012) and was stored in a desiccator during transport and until use to avoid re-oxidation.…”

Options for the Separation and Immobilization of Technetium

“…• reductive precipitation, e.g., using Sn 2+ either alone or in combination of another sorbent such as hydroxy-apatite (McCabe et al 2013;Taylor-Pashow et al 2014a;Duncan et al 2012), and…”