A significant amount of high level waste (HLW) has been generated from reprocessing in the Hanford and Savannah River Sites (SRS) during the cold-war years. The current treatment of HLW at SRS includes two processes: The Actinide Removal Process (ARP) which involves sorption of strontium and actinides on monosodium titanate and the Next-Generation Caustic-Side Solvent Extraction process (NG-CSSX, which involves cesium extraction by calixarene ligands). ARP is a relatively slower process than solvent extraction and thus is the kinetic bottleneck in the current integrated HLW processing. Actinide complexation by organic ligands that are compatible with the NG-CSSX solvent could potentially lead to a combined caustic-side Cs/Sr/actinide extraction process with better economics due to a reduced amount of monosodium titanate and/or a shorter required contact time with titanate during ARP. Rigid o-phenylenediamine-derived disulfonamides (pKa ~ 9-11) possess a favorable configuration of soft N-donor sites compared to pyrocatechols, which were found to be the most promising ligands for An(III) binding and separation in alkaline media, but also easily oxidizable under these conditions. In this work alkyl-substituted disulfonamides were synthesized and spectroscopically characterized. Dichloromethane solutions of ligands were used for extraction of Sm(III) (used as an actinide surrogate) from alkaline aqueous media (pH = 10.5 – 14). Consecutive stripping of organic phases was carried out with 0.1M HNO3. Obtained acidic solutions have been analyzed by ICP-OES and the Arsenazo III UV-Vis spectrophotometric method. Extraction removal of Ln(III) was found to occur at wide pH range with two maxima at pH ~ 11.5 and 12.5.

o-Phenylenediamine derived sulfonamides for lanthanide and actinide extraction from alkaline aqueous media

2019 Spring National Meeting

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