Use of Macrocycles in Nuclear-Waste Cleanup: A Realworld Application of a Calixcrown in Cesium Separation Technology

Temperature-dependent IR spectroscopic and structural study of 18-crown-6 chelating ligand in the complexation with sodium surfactant salts and potassium picrate

“…The group of macrocyclic polyethers, known as crown ethers, have become valuable tools in organic synthesis due to their ability to solvate alkali, alkaline-earth, transition-metal, and ammonium cations [1][2][3][4]. Their selective cation binding makes them applicable for different environmental usage [5,6], drug delivery [7,8], recovery or removal of specific species, models for biological receptors [9], reaction catalysts as well as active sites in ion selective electrodes [10] or chromatographic agents [11]. Alkali metal elements have indispensable role in many biological processes, primarily to be as bulk electrolytes that stabilize surface charges on proteins and nucleic acids [12], and also play unique structural roles in biological systems [13,14].…”

Recommended Guanidine Suppressor for the Next-Generation Caustic-Side Solvent Extraction Process

“…Table 6 below shows a small effect of the surfactant SDS, confirming the effectiveness of the suppressing action of all guanidine candidates except TsBPG. Surfactant was earlier identified as a potential interferent in CSSX, and the mechanism of the role of TOA has been discussed [3,4] . In brief, the surfactant anion is more lipophilic than other anions in the system and thereby acts to make cesium more extractable, resisting stripping.…”

“…The NG-CSSX process [1,2] was designed to provide a step-jump improvement in waste decontamination factor (DF) and waste throughput vs. the CSSX process [3,4,5] in the removal of cesium from legacy high-level salt waste stored in underground storage tanks in the U.S. Department of Energy (DOE) complex. Following initial results pointing to its feasibility [6,7,8] , the NG-CSSX process has been under development since 2010 under funding from the DOE Office of Environmental Management, Office of Technology Innovation and Development.…”

“…The structures of the next-generation solvent (NGS) components are shown in Table 1. The chemical role of each component has been described previously [1,3] . In particular, the ability to employ the extractant MaxCalix at 50 mM vs 7 mM for BOBCalixC6 in the CSSX process [3,5] increased the cesium extraction strength and allowed the Cs-7SB modifier concentration to be decreased to 0.5 M. Although it is a minor component of the solvent, the suppressor is essential for stripping.…”

“…The chemical role of each component has been described previously [1,3] . In particular, the ability to employ the extractant MaxCalix at 50 mM vs 7 mM for BOBCalixC6 in the CSSX process [3,5] increased the cesium extraction strength and allowed the Cs-7SB modifier concentration to be decreased to 0.5 M. Although it is a minor component of the solvent, the suppressor is essential for stripping. In the CSSX process, tri-n-octylamine (TOA) is used as the suppressor, but it was found to be ineffective for stripping with the aqueous boric acid solution used in NG-CSSX [2] , requiring the use of a more basic suppressor.…”