Shinsuke Yamada

Dependence of Lanthanide-Ion Binding Performance on HDEHP Concentration in HDEHP Impregnation to Porous Sheet

An octadecylamino-group-introduced polymer chain grafted onto a porous sheet was impregnated with bis(2-ethylhexyl)hydrogen phosphate (HDEHP). A mixture of HDEHP and ethanol of various HDEHP concentrations was used for the impregnation. The porous sheet into which a C18H37NH group was introduced was immersed in HDEHP/ethanol solution before ethanol evaporation. The liquid permeability of a cartridge charged with the HDEHP-impregnated porous sheet in disk form prepared in 50 (v/v)% HDEHP/ethanol solution was 96% that of the starting-porous-disk-packed cartridge. The equilibrium binding capacity of the HDEHP-impregnated porous disk for yttrium ions was 0.32 mol per kg of the disk. In addition, the HDEHP-impregnated-porous-disc-packed cartridge was found to be applicable to the preconcentration of trace amounts of lanthanides in a multielement solution prior to their measurement by inductively coupled plasma mass spectrometry.

Preparation of Microvolume Anion-Exchange Cartridge for Inductively Coupled Plasma Mass Spectrometry-Based Determination of 237Np Content in Spent Nuclear Fuel

Microvolume anion-exchange porous polymer disk-packed cartridges were prepared for Am/Np separation, which is required prior to the measurement of Neptunium-237 ((237)Np) with inductively coupled plasma mass spectrometry (ICPMS). Disks with a volume of 0.08 cm(3) were cut out from porous sheets having anion-exchange-group-containing polymer chains densely attached on the pore surface. Four different amine-based groups, N,N-dimethylaminoethyl methacrylate, trimethylammonium, diethylamine, and triethylenediamine (TEDA), were selected as the anion-exchange groups to be introduced into the porous sheets. The separation performances of Am/Np were evaluated using a standard solution of (243)Am, which had the same activity as its daughter nuclide (239)Np in secular equilibrium. (239)Np recovery of close to 100% with practically no contamination of (243)Am was achieved using the TEDA-introduced disk-packed cartridge. The time to elute (239)Np from the cartridge was approximately 40 s. The TEDA-introduced disk-packed cartridge was applied to the separation of Np from a spent nuclear fuel sample to confirm its separation performance. A known amount of (243)Am ((239)Np) was added to the spent nuclear fuel sample solution to monitor the chemical yield of Np. The chemical yield of Np calculated from a measured concentration of (239)Np was 90.4%. Am leakage in the Np-eluted solution was less than 1 ppt, corresponding to 0.001% of the original Am concentration in the sample. This indicates that no additional (239)Np was produced by the decay of the (243)Am remaining in the Np-eluted solution, thus providing a reliable chemical yield. U, which can cause a serious spectral interference involving the peak tail from the mass spectrum of (238)U, was thoroughly removed with the TEDA cartridge, providing interference-free measurement of (237)Np. The concentration of (237)Np obtained by ICPMS was 718 ± 12 ng/mg-U, which agrees well with the theoretically calculated value. Compared with the conventional separation technique using commercially available anion-exchange resin columns, the time required to adsorb, wash, and elute Np using the TEDA- introduced disk-packed cartridge was reduced by 75%.

Crosslinked-Chelating Porous Sheet with High Dynamic Binding Capacity of Metal Ions

A crosslinked chelating porous sheet was prepared by cografting ethylene glycol dimethacrylate (EGDMA) with glycidyl methacrylate onto an electron-beam-irradiated porous polyethylene sheet, followed by the introduction of an iminodiacetate group. At a molar percentage of EGDMA of 1.0 mol%, the sheet exhibited a maximum dynamic binding capacity for copper ions of 0.93 mmol/g, while the equilibrium binding capacity remained the same (1.2 mmol/g) as that of a non-crosslinked chelating porous sheet. The crosslinking of the grafted chain causes copper ions to lower their diffusion rate along the sheet thickness driven by the gradient of the amount of copper ions adsorbed.

Simple Method for High-Density Impregnation of Aliquat 336 onto Porous Sheet and Binding Performance of Resulting Sheet for Palladium Ions

Aliquat 336 was impregnated onto the polymer chain grafted onto a 2.0-mm-thick porous sheet with a porosity of 75% and a pore size of 1.2 µm via the graft polymerization of glycidyl methacrylate and the subsequent reaction of the epoxy group with mercaptoundecanoic acid. In a 2:1 ethanol/4M NaOH (v/v) mixture, Aliquat 336 was impregnated at a density of 0.85 mmol/g, which was comparable to that of conventional Aliquat-336-impregnated polymeric beads. The dynamic binding capacity for palladium was 0.60 mmol/g when 100 mg-Pd/L palladium chloride solution was forced to permeate at a space velocity of 3700 h−1.

Rapid separation of zirconium using microvolume anion-exchange cartridge for 93 Zr determination with isotope dilution ICP-MS

Estimating the risks associated with radiation from long-lived fission products (LLFP) in radioactive waste is essential to ensure the long-term safety of potential disposal sites. In this study, the amount of 93Zr, a LLFP, was determined by ICP-MS after separating Zr from a spent nuclear fuel solution using a microvolume anion-exchange cartridge (TEDA cartridge). Zirconium in 9.4 M HCl was stably retained on the TEDA cartridge and readily eluted with 0.75 mL of a mixed solution of 9.4 M HCl and 0.01 M HF. The time taken to complete the Zr separation was 1.2 min. Almost all the other elements initially present in the spent nuclear fuel sample were removed, leading to accurate measurement of all six Zr isotopes (90Zr, 91Zr, 92Zr, 93Zr, 94Zr, and 96Zr). This demonstrated that the TEDA cartridge allowed highly selective separation of Zr regardless of its small bed volume of 0.08 cm3. The concentrations of these isotopes were determined by an isotope-dilution method using a natural Zr standard that has a different isotopic composition from that of the spent nuclear fuel sample. The amount of 93Zr in an initial spent nuclear fuel pellet was 1081 ± 79 ng per mg of 238U. The measured concentrations of all Zr isotopes, as well as the isotopic composition, were consistent with values predicted using a burnup calculation code.