Evaluating the Effects of Tributyl Phosphate (TBP) and Normal Paraffin Hydrocarbon (NPH) in Simulated Low-Activity Waste Solution on Ion Exchange

Abstract:

Ultrafiltration and ion exchange are among the pretreatment processes selected for the Waste Treatment Plant at the U.S. Department of Energy’s Hanford Site. Envelope B AZ-101 waste may contain tributyl phosphate (TBP) and normal paraffin hydrocarbon (NPH)-dodecane, as dissolved species and also as a separate phase.

This study is the second part of a two-part study on Evaluating the Effects of TBP and NPH (dodecane) in Simulated Low-Activity Waste Solution on Ultrafiltration and Ion Exchange. The first study dealt with ultrafiltration. The second part involved using filtrates from the ultrafiltration work to perform resin sorption experiments using SuperLig® 644 and SuperLig® 639 resins. SuperLig® 644 resin has a high selectivity for cesium, while SuperLig® 639 resin is highly selective for rhenium as perrhenate (the surrogate for pertechnetate). What is unknown is the effect the organics may have on these resins’ high-sorption capacities for cesium and rhenium.

The goal of the study was to evaluate the effectiveness of the resins to remove cesium and rhenium from AZ-101 simulant containing organics by comparing to the baseline case (i.e., AZ-101 simulant containing no organics) using both batch contact and small-scale column tests.

The batch contact work demonstrated there is no statistically significant effect of organics (TBP, dodecane, and their degradation products) on cesium and rhenium sorption by SuperLig® 644 and SuperLig® 639 resins, respectively, from AZ-101 simulant solution. Both the cesium and rhenium column breakthrough/elution profile curves for simulants with and without organics were virtually identical, which is an indication of a no-organics effect.