Uptake of plutonium on a novel thin film for use in spectrometry

Abstract

Trace elemental and isotopic analysis of actinides via Thermal Ionization Mass Spectrometry (TIMS) is often difficult and time consuming due to intensive sample preparation. Polymer thin films show strong potential for rapid concentration of radionuclides from solution that may prove as suitable substrates for TIMS analyses. In this work, a polymer thin film (~180 nm) was coated onto a silicon substrate and utilized for rapid radioanalytical analysis. The polymer is composed of poly(vinyl benzyl chloride) functionalized with triethyl amine (TEA) to produce an anion-exchange site for concentrating anionic actinide complexes (i.e. PuCl 6 2-, Pu(NO 3) 6 2-) from solution. In addition, selectively functionalizing "spots" with TEA creates hydrophilic regions and allows for concentration of an aqueous drop when surrounded by the hydrophobic polymeric backbone. Batch uptake studies were performed using inductively coupled plasma mass spectrometry, liquid scintillation counting and alpha spectrometry to determine uptake kinetics and anion-exchange capacities of the polymer thin film. Results indicated that along with a potential for utilization as a TIMS substrate, the polymer thin film yields high resolution alpha spectra, comparable to samples produced via electrodeposition. An apparent equilibrium constant (K d) for the functionalized polymer was found to be approximately 9060 L/kg from 9M HCl. The anion exchange capacity of the film was determined using 36 Cl uptake studies and found to be 1.25 x 10-1 ± 1.07 × 10-2 meq/g polymer. Thus, the rapid uptake kinetics, good anion-exchange capacity, and high-resolution alpha spectra show good promise for the use of this thin film for rapid radioanalytical analyses. v

Membranes for the Capture and Screening of Waterborne Plutonium Based on a Novel Pu-Extractive Copolymer Additive

“…To reduce the time to prepare an alpha spectrometry source, we and others have turned to developing Pu extractive membranes that can concentrate Pu to detectable limits and serve directly as the sample source. Membranes are functionalized for Pu capture either by casting a polymer-ligand film onto the membrane surface, or by utilizing a reactive surface from which a ligand layer can be grafted [5][6][7][8][9][10]. By keeping the functional layer relatively thin, high spectral resolutions can be achieved that rival electrodeposited sources.…”

Extraction of plutonium using DIPEX immobilized in polystyrene thin films

“…These techniques involve sample dissolution, concentration, and extraction using high-affinity thin films and sample analysis by alpha spectrometry. Extraction of plutonium and other actinides is achieved using functionalized thin films that have a very high affinity for actinide adsorption [14][15][16][17]. The thin films are functionalized by covalent incorporation of specific functional groups onto the polymer structure or the immobilization of ligands with high binding affinity for actinides in the rigid structures of inert polymers.…”

Functionalized Polymer Thin Films for Plutonium Capture and Isotopic Screening from Aqueous Sources

“…In recent studies, functionalized polymer films and thin-film composite membranes have been demonstrated for the extraction and screening of various radioisotopes in water. − Combined with alpha spectrometry, these substrates greatly reduce the time involved for isotopic screening by combining purification, concentration, and sample mounting steps. Approaches to developing the functionalized polymer thin films fall into two general categories, the first being physical immobilization or encapsulation of extractive ligands into a polymer matrix, akin to how an extractive chromatography resin is formed.…”