Small-Column Cesium Ion Exchange Elution Testing of Spherical Resorcinol-Formaldehyde

Abstract

Ion exchange using the Spherical Resorcinol-Formaldehyde (SRF) resin has been selected by the U.S. Department of Energy's Office of River Protection (DOE-ORP) for use in the Pretreatment Facility (PTF) of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) and for potential application in an at-tank deployment. Numerous studies have shown the SRF resin to be effective for removing 137 Cs from a wide variety of actual and simulated tank waste supernatants (Adamson et al. 2006; Blanchard et al. 2008; Burgeson et al. 2004; Duignan and Nash 2009; Fiskum et al. 2006a; Fiskum et al. 2006b; Fiskum et al. 2006c; Fiskum et al. 2007; Hassan and Adu-Wusu 2003; King et al. 2004; Nash et al. 2006; Thorson and Gilbert 2007). Much of the prior work at Pacific Northwest National Laboratory (PNNL) in this area focused primarily on the loading behavior for 4 to 6 M sodium (Na) solutions at 25°C to 45°C and the eluting behavior of the loaded SRF resin with virgin 0.5 M HNO 3 . In addition, various alternative acid concentrations and elution strategies have been investigated (Taylor and Johnson 2009; Burgeson et al. 2004). Recent proposed changes to the WTP ion exchange process baseline indicate that loading may include a broader range of sodium molarities (2 to 8 M) and higher temperatures (50°C) to alleviate post-filtration precipitation issues. In addition, elution will likely use variable-strength recycled nitric acid containing trace impurities of 137 Cs.This report summarizes the work performed to evaluate multiple, cesium loading, and elution cycles for small columns containing SRF resin using a simple, high-level waste (HLW) simulant. Cesium ion exchange loading and elution curves were generated for a nominal 5 M Na, 2.4E-05 M Cs, 0.115 M Al loading solution traced before beginning testing with 134 Cs. This was followed by elution with variable HNO 3 (0.02, 0.07, 0.15, 0.23, and 0.28 M) containing variable CsNO 3 (5.0E-09, 5.0E-08, and 5.0E-07 M) and traced before beginning testing with 137 Cs. The use of two separate cesium process tracers ( 134 Cs and 137 Cs) facilitated the monitoring of cesium behavior from multiple sources (e.g., from the loading and elution solution, respectively). The ion exchange system consisted of a pump, tubing, process solutions, and a single, small (~15.7 mL) bed of SRF resin with a water-jacketed column for temperature-control. The columns were loaded with approximately 250 bed volumes (BVs) of feed solution at 45°C and at 1.5 to 12 BV per hour (0.15 to 1.2 cm/min). The columns were then eluted with 29+ BVs of HNO 3 processed at 25°C and at 1.4 BV/h. The two independent tracers allowed analysis of the on-column cesium interaction between the loading and elution solutions. The objective of these tests was to improve the correlation between the spent resin cesium content and cesium leached out of the resin in subsequent loading cycles (cesium leakage) to help establish acid strength and purity requirements. S.1 ObjectiveThe test objectives were to: Determine the impact of re...

Stabilization of Spherical Rescorcinol Resin in Grout- Maintenance of the Hanford Integrated Disposal Performance Assessment FY 2018

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Development of an Approach to Modeling Loading and Elution of Spherical Resorcinol Formaldehyde Ion-Exchange Resin

“…In these studies varying and sometimes persistent tailing of the elution curves exist. More recent studies (Brown et al, 2011) indicate that cesium removal using more dilute HNO 3 is possible. Based on the prior experimental studies and the desire to consider process baseline changes, it is recognized that modeling of the elution process can assist in process optimization studies.…”

Effect of the Resorcinol/Formaldehyde Ratio and the Temperature of the Resorcinol–Formaldehyde Gel Solidification on the Chemical Stability and Sorption Characteristics of Ion-Exchange Resins

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