Separation behavior of MA(III) from simulated high-level liquid waste using TEHDGA and HONTA impregnated XAD7-HP adsorbents

Separation behavior of MA(III) from simulated high-level liquid waste using TEHDGA and HONTA impregnated XAD7-HP adsorbents | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Separation behavior of MA(III) from simulated high-level liquid waste using TEHDGA and HONTA impregnated XAD7-HP adsorbents Masahiko Kubota, Seong-Yun Kim, Tsuyoshi Arai, Sou Watanabe, Tatsuya Ito, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8747230/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract To achieve selective adsorption and separation of minor actinides (MA(III)) from lanthanides (Ln(III)), impregnated adsorbents were prepared by loading Amberlite XAD7-HP particles with tetra-2-ethylhexyl diglycolamide (TEHDGA) and hexaoctyl nitrilotriacetamide (HONTA), respectively. Batch experiments were performed to evaluate the adsorption characteristics of TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents toward MA(III) and simulated fission products in HNO 3 solutions. Particle-induced X-ray emission analysis confirmed the uniform distribution of Eu(III) on the adsorbent surface. This study establishes a process for separating MA(III) using TEHDGA/XAD7-HP and HONTA/XAD7-HP column systems. Minor actinide Extraction chromatography TEHDGA HONTA XAD7-HP Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Introduction In recent years, artificial intelligence and data centers have developed rapidly to analyze and process vast amounts of data, becoming indispensable to modern industrial activities. At the same time, society faces a growing challenge of sharply increasing electricity consumption [ 1 – 3 ]. To ensure a stable power supply and mitigate environmental degradation and climate change associated with the use of fossil fuels, nuclear power generation, which can produce large amounts of electricity, is being adopted worldwide [ 4 , 5 ]. Spent nuclear fuel generated after power generation is reprocessed (e.g., through the PUREX process) to recover reusable materials such as uranium (U) and plutonium (Pu) while reducing waste volume. High-level radioactive liquid waste (HLLW) produced during this process contains large quantities of radioactive fission products. Among them, minor actinides (MA(III)) possess long half-lives and significantly influence the long-term radioactivity of HLLW. Reducing the volume and radioactivity of HLLW prior to final disposal therefore remains a critical challenge [ 6 – 9 ]. However, because HLLW contains large amounts of lanthanides (Ln(III)) with chemical properties similar to those of actinides, the selective separation of MA(III) from HLLW is extremely difficult[ 10 – 13 ]. HLLW contains a large number of fission products, making it extremely difficult to accurately separate specific nuclides. To date, various methods such as precipitation [ 14 ], solvent extraction [ 15 – 17 ], and membrane separation [ 18 – 19 ] have been attempted to separate MA(III) from HLLW. However, these methods have drawbacks such as slow reaction rates, low capacity, and poor selectivity. In recent years, significant progress has been made in the precise separation of MA(III) using extraction chromatography [ 20 – 22 ]. This method offers several advantages, including the ability to design adsorbents using various combinations of carriers and extractants, ease of adsorbent preparation, and high selectivity. For example, various types of silica-based solid-phase adsorbents have been reported for the selective and efficient separation of MA(III) from simulated HLLW.[ 23 ] Our research group investigated a two-stage separation process using adsorbents containing N,N,N',N'-tetra(2-ethylhexyl)diglycolamide (TEHDGA) and hexaoctyl nitrilotriacetamide (HONTA). [ 24 , 25 ] The objective of this study was to evaluate the separation process using these adsorbents and achieve a two-stage separation of MA(III) and Ln(III). Co-separation evaluation of MA(III) and Ln(III) in the TEHDGA column and mutual separation evaluation of MA(III) and Ln(III) in the HONTA column are in progress. However, to establish a more effective process for the mutual separation of MA and Ln using extraction chromatography, fundamental research is necessary. In this study, we focused on Amberlite XAD7-HP as the adsorbent material. XAD7-HP is a white spherical polymer with a macroporous structure composed of cross-linked copolymers and exhibits a large specific surface area. Compared with ion exchange resins, it offers superior properties such as high chemical stability due to the absence of functional groups [ 26 – 28 ]. Although XAD7-HP has been widely used in adsorption and separation applications, studies on its use for separating Ln(III) and MA(III) from HLLW have been limited. In this study, we investigated the separation of MA(III) from simulated HLLW solutions using TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents. Specifically, the characteristics of TEHDGA/XAD7-HP and HONTA/XAD7-HP were evaluated using SEM, XRD, TG, and N 2 adsorption–desorption analyses. Furthermore, the effects of HNO 3 concentration, contact time, chemical stability, and γ-ray irradiation under HNO 3 solution conditions were examined to assess the stability and performance of the adsorbents. Finally, column experiments were conducted using simulated HLLW solutions containing 241 Am and 152 Eu to investigate their dynamic adsorption and separation behavior. Experimental Materials The TEHDGA and HONTA extractants (Fig. 1 ) were synthesized according to previously reported procedures [ 29 , 30 ]. All reagents used in this study were of analytical grade. The reagents employed to prepare the simulated high-level radioactive waste solution included lanthanum(III) nitrate hexahydrate, cerium(III) nitrate hexahydrate, neodymium(III) nitrate hexahydrate, samarium(III) nitrate hexahydrate, europium(III) nitrate hexahydrate, gadolinium(III) nitrate hexahydrate, cesium(I) nitrate, strontium(II) nitrate, barium(II) nitrate, zirconium(IV) nitrate oxide, and ammonium molybdate heptahydrate, all purchased from Kanto Chemical Co., Ltd. Nitrosylruthenium(III) nitrate solution, palladium(II) nitrate, and rhodium(III) nitrate solution were obtained from Sigma-Aldrich, while rhenium(VII) oxide was purchased from Sanwa Chemical Industries Co., Ltd. All reagents were subdivided and prepared by dissolving them in nitric acid (HNO 3 ). Ultrapure water with a specific resistivity of at least 18.3 MΩ·cm was used in all experiments. The radioactive isotopes 241 Am and 152 Eu were used to evaluate the adsorption and separation behavior of MA(III) and Ln(III). 241 Am (37 MBq) and 152 Eu (37 MBq) were separated and diluted from their original vials to prepare a mixed solution containing 241 Am and 152 Eu ( 241 Am: 100 kBq/mL, 152 Eu: 500 kBq/mL). The prepared mixture was spiked into the simulated high-level radioactive liquid waste solution to obtain the working solution. Preparation of XAD7-HP impregnated adsorbents Before synthesizing the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents, the porous XAD7-HP particles were washed three times with CH 3 OH to remove impurities from within the pores, followed by vacuum drying at 313 K for 24 h to eliminate residual methanol. The TEHDGA and HONTA extractants were completely dissolved in 300 mL of CH 2 Cl 2 as the diluent in a round-bottom flask. Subsequently, 40.0 g of thoroughly dried XAD7-HP particles were added, and the mixture was stirred at room temperature for 120 min. The extractants were then immobilized within the pores of the XAD7-HP particles by gradually removing the diluent under reduced pressure at 313 K using a rotary evaporator. Any residual CH 2 Cl 2 was further removed by vacuum drying at 313 K for one day, yielding the final XAD7-HP-based adsorbents. Characterization The surface morphology of the samples was examined using a scanning electron microscope (SEM, TM4000Plus) equipped with an energy-dispersive X-ray analyzer. Thermogravimetric analysis (TG) was conducted using a Shimadzu DTG-60/60H instrument under an N 2 atmosphere (30 mL/min) at a constant heating rate of 1°C/min over a temperature range of 25–600°C. For Brunauer–Emmett–Teller (BET) surface area analysis, the prepared samples were degassed overnight under vacuum at 70°C. N 2 adsorption–desorption measurements were carried out using a Microtrac Belsorp Max analyzer under a liquid N 2 atmosphere (− 195.8°C) at a P/P 0 ratio of 0.99. X-ray photoelectron spectroscopy (XPS) was performed using a Shimadzu AXIS-ULTRA spectrometer. The behavior of TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents before and after adsorption experiments was further investigated in the solid state by photon-induced X-ray emission (PIXE) using the Microbeam MB-I system equipped with a 4.5 MeV Dynamitron accelerator at Tohoku University. The particulate target samples were irradiated with a 3 MeV proton beam focused to a spot size of 1 × 1 µm 2 . X-rays emitted from the elements adsorbed on the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents were collected, and elemental distribution maps were generated using GeoPIXE II software. Batch adsorption experiments The TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents were subjected to radioactive adsorption experiments with respect to 241 Am and 152 Eu ions as a function of HNO 3 concentration at 298 K in a thermostatic shaker. The working solutions were prepared by adding stock solutions of 241 Am and 152 Eu to solutions containing six elements (5 mM) at different HNO 3 concentrations. Subsequently, 0.2 g of the TEHDGA/XAD7-HP or HONTA/XAD7-HP adsorbent was placed in a 13.5 mL glass bottle with a plastic cap and mixed with 4 mL of the prepared solution. The mixture was shaken vigorously for a predetermined period to ensure sufficient contact between the solid and liquid phases. After equilibration, the solid and aqueous phases were separated using a syringe and a nylon mesh filter. The radioactivity of 241 Am and 152 Eu before and after adsorption was measured by detecting γ-rays at 59.5 keV ( 241 Am) and 122 keV ( 152 Eu), respectively, using a Canberra Ge semiconductor detector. Measurement data were analyzed using Canberra Genie 2000 software. The distribution coefficient ( K d ; cm 3 g⁻ 1 ) for each metal ion was calculated using the following equation [ 31 ]: K d = \(\:\frac{{C}_{0}-{C}_{e}}{{C}_{e}}\times\:\frac{V}{m}\) (1) where C 0 and C e represent the initial and equilibrium concentrations of the metal ions (mM), respectively, V is the volume of the solution (cm 3 ), and m is the mass of the TEHDGA/XAD7-HP or HONTA/XAD7-HP adsorbent (g). Column separation experiments To investigate the dynamic adsorption and separation behavior of 241 Am, 152 Eu, and other metal ions on the adsorbents, column separation tests were conducted. The experimental setup consisted of Pyrex glass columns (10 mm Φ × 150 mm H for TEHDGA/XAD7-HP and 10 mm Φ × 100 mm H for HONTA/XAD7-HP), a hot-water circulation jacket, a metering pump, a fraction collector, and a constant-temperature hot-water circulation system. As in the batch tests, the feed solutions for column experiments were simulated high-level radioactive liquid waste (HLLW) solutions containing 241 Am, 152 Eu, and lanthanide elements, prepared at specified HNO 3 concentrations. Prior to column packing, the fractionated TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents were immersed in pure water and degassed for 2 h to remove trapped air. The degassed adsorbents were then wet-packed into the glass columns. For column conditioning, an HNO 3 solution with the same concentration as the simulated HLLW feed was passed through the adsorbent-packed columns at a constant temperature. Subsequently, the simulated HLLW feed was introduced, followed by HNO 3 of the same concentration to elute unadsorbed components. Finally, the adsorbed components were recovered by passing pure water through the TEHDGA/XAD7-HP column and 1 M nitric acid through the HONTA/XAD7-HP column. Results and discussion Characterization of the adsorbent To elucidate the physicochemical properties of the TEHDGA- and HONTA-impregnated adsorbents, SEM, TG, N 2 adsorption–desorption, XPS, and PIXE analyses were conducted. SEM observations (Fig. 2 (a)) revealed that the surface morphology of the adsorbents was similar to that of the XAD7-HP support, with no visible extractant precipitation. This confirms that no extractant remained on the outer surface and that impregnation of the extractant occurred within the pores of the XAD7-HP support. Next, the TG curve of the XAD7-HP adsorbent was obtained (Fig. 2 (b)). As the temperature increased, a significant weight loss was observed around 300°C. This behavior is attributed to the combustion of extractant immobilized within the XAD7-HP pores and the thermal decomposition of the XAD7-HP matrix, which consists primarily of carbon, hydrogen, and oxygen. The onset of decomposition at approximately 300°C demonstrates the excellent thermal stability of the XAD7-HP–based impregnated adsorbents. Figure 2 (c) shows the N 2 adsorption–desorption isotherms of the XAD7-HP support and the TEHDGA/XAD7-HP and HONTA/XAD7-HP composites. According to IUPAC classification, all samples exhibited Type IV isotherms, characteristic of mesoporous materials with cylindrical pores in the 2–50 nm range [ 32 ]. After impregnation, the average pore diameter, specific surface area, and total pore volume were 8.493 nm, 150.1 m 2 g⁻ 1 , and 0.6374 cm 3 g⁻ 1 for TEHDGA/XAD7-HP, and 8.229 nm, 165.6 m 2 g⁻ 1 , and 0.6812 cm 3 g⁻ 1 for HONTA/XAD7-HP 2233 , respectively. These values were lower than those of the unmodified XAD7-HP support (8.894 nm, 554.1 m 2 g⁻ 1 , and 1.232 cm 3 g⁻ 1 ), indicating that the incorporation of TEHDGA and HONTA extractants reduced the porosity of the XAD7-HP matrix. Figure 3 presents the X-ray spectra of the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents before and after adsorption, as determined by PIXE analysis, to investigate solid-state adsorption behavior. After contact with a 10 mM Eu(III) solution, new peaks corresponding to Eu appeared in the 5–10 keV energy range. These results indicate that Eu(III) was uniformly distributed over the surfaces of both TEHDGA and HONTA adsorbents after adsorption, suggesting that the extractants were homogeneously impregnated into the XAD7-HP support during synthesis. HNO concentration dependence of Am and Eu adsorption The influence of nitric acid concentration on the adsorption behavior of minor actinide elements and coexisting metal ions on the impregnated adsorbents was examined. The results, expressed as distribution coefficients ( K d ), are shown in Fig. 4 . For TEHDGA/XAD7-HP, the observed trends in K d values for elements other than 241 Am were generally consistent with those obtained in previous batch studies using TEHDGA/SiO 2 –P adsorbents [ 33 ]. It is therefore expected that the distribution coefficient of 241 Am follows a similar trend. In contrast, HONTA/XAD7-HP exhibited a high distribution coefficient at low nitric acid concentrations, with K d values decreasing as the acidity increased. Moreover, the adsorption of coexisting rare earth elements resulted in a decline in the overall distribution coefficient, implying competitive adsorption between 241 Am and 152 Eu. However, within the HNO 3 concentration range of 0.01–0.1 M, a clear difference in K d values between 241 Am and 152 Eu was observed. These findings suggest that column operating conditions for MA(III)/Ln(III) separation can be optimized within this acidity range. The reduction in K d at higher HNO 3 concentrations is likely due to the formation of HONTA–nitrate complexes, which hinder the efficient coordination and adsorption of MA(III). Chemical stability After mixing the impregnated adsorbents with HNO 3 solution, the total organic carbon (TOC) content in the solution was measured. The eluate was analyzed to evaluate the stability of the adsorbents. Figure 6 shows the dependence of TOC concentration in the aqueous phase on HNO 3 concentration. The TOC concentration exhibited a tendency to increase with increasing HNO 3 concentration. However, the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents prepared in this study exhibited a leaching rate of approximately 1% at all HNO 3 concentrations. These results demonstrate that the adsorbents are highly stable and do not cause a significant increase in TOC concentration. Therefore, extractant loss from the adsorbents during column testing is expected to be minimal. Effect of γ-ray irradiation Under actual processing conditions, adsorbents are exposed to radiation, which may lead to degradation of adsorption performance through decomposition of organic extractants, leaching of degradation products, or weakening of the organic matrix. To investigate radiation-induced degradation, the carbon leakage rate from the adsorbents was determined from TOC values in the liquid phase of gamma-irradiated samples obtained at various absorbed doses using a Co-60 source. Solid–liquid ratios of 20 and 1.5 were employed, corresponding to batch adsorption and column separation conditions, respectively [ 34 ]. Specifically, 0.2 g of adsorbent was contacted with 4.0 mL (solid–liquid ratio 20) or 0.3 mL (solid–liquid ratio 1.5) of 2 M HNO 3 solution. As shown in Figs. 8 and 9 , no significant carbon leakage from the XAD7-HP particles was observed after γ-ray irradiation up to approximately 700 kGy. Within this dose range, no abrupt increase in carbon leakage was detected, indicating minimal irradiation-induced structural deterioration. Figures 10 and 11 present the effect of radiation-induced extractant decomposition on the adsorption performance of TEHDGA/XAD7-HP and HONTA/XAD7-HP for various metal ions. A gradual decrease in adsorption capacity was observed with increasing absorbed dose up to 700 kGy, suggesting that extractant decomposition by γ-radiation led to reduced adsorption performance. For Pd(II), a pronounced decrease in the distribution coefficient was noted up to 200 kGy. Conversely, Zr exhibited a gradual increase in adsorption rate with increasing absorbed dose, which may be attributed to the formation of radiation-induced decomposition products with enhanced affinity toward Zr. Column Experiment Figure 12 presents the results of column experiments conducted using the TEHDGA/XAD7-HP adsorbent at a flow rate of 3 mL min⁻ 1 . Initially, 7 M nitric acid solution was introduced as the eluent to remove elements other than 241 Am, Ln(III), and Zr. Non-adsorbed components were rapidly eluted, whereas the adsorbed components were retained on the impregnated adsorbent. Subsequently, distilled water was introduced to separate and recover the target elements— 241 Am, 152 Eu, and Ln(III)—that had been retained on the adsorbent. A mixed solution containing minor actinide elements (including 241 Am and 152 Eu) and lanthanide elements was successfully recovered. Table 1 summarizes the recovery ratios for each element obtained from the column experiments. Nearly all elements exhibited high recovery efficiencies. In the case of Zr, residual quantities remaining within the column could likely be recovered by passing an ethylenediaminetetraacetic acid (EDTA) solution through the system. Next, Fig. 13 shows the chromatographic separation results obtained using the HONTA/XAD7-HP adsorbent at a flow rate of 1 mL min⁻ 1 . After introducing the feed and elution solutions, non-adsorbed components, including Ln(III) and 152 Eu, were rapidly eluted. Subsequently, 241 Am was eluted, confirming that the HONTA/XAD7-HP adsorbent possesses the potential to selectively separate 241 Am from solutions containing both 241 Am and Ln(III). The recovery ratios for all analyzed elements were 100% (Table 2 ), and no detectable residual material remained within the column. However, the peaks corresponding to Ln(III) and MA(III) were closely spaced, indicating that the adsorption–desorption reactions between metal ions and the extractant proceed relatively slowly. Therefore, longer contact times or optimization of the flow rate and column dimensions—particularly increasing column length—may be required to achieve complete separation. Table 1 Recovery ratios of 241 Am and 152 Eu using the TEHDGA-packed column in the presence of Ln elements Recovery ratio (%) Recovery ratio (%) Recovery ratio (%) 241 Am 100 Eu 100 Rh 100 152 Eu 100 Gd 100 Pd 100 La 100 Cs 100 Zr 85.7 Ce 99.9 Sr 100 Mo 100 Nd 100 Ba 100 Re 100 Sm 100 Ru 100 Table 2 Recovery ratios of 241 Am and 152 Eu using the HONTA-packed column in the presence of Ln elements Recovery ratio (%) Recovery ratio (%) 241 Am 100 Eu 100 152 Eu 100 Gd 100 La 100 Ce 100 Nd 100 Sm 100 Conclusion A novel adsorption and separation process employing TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents impregnated onto porous XAD7-HP supports was successfully developed. The effects of HNO 3 concentration on the adsorption and column separation behaviors of 241 Am(III) and 152 Eu(III) from HNO 3 solutions were systematically investigated. The adsorption capacities of Am(III) and Eu(III) on HONTA/SiO 2 –P decreased with increasing HNO 3 concentration; however, distinct differences in the K d values of Am(III) and Eu(III) were observed at lower acid concentrations. PIXE analysis after batch testing confirmed that the TEHDGA and HONTA extractants were uniformly impregnated into and retained within the pores of the XAD7-HP matrix. The prepared adsorbents exhibited excellent chemical stability and radiation resistance. Column separation experiments using a combination of TEHDGA/XAD7-HP and HONTA/XAD7-HP carriers effectively achieved the separation of Am(III) and Eu(III) from HNO 3 solutions. Although coexisting elements influenced the separation behavior, varying the nitric acid concentration in the eluent enabled efficient separation of Am(III) from the various Ln(III) ions. Declarations Conflict of interest The authors declare that they have no conflicts of interest or involvement with any organization or entity having financial or non-financial interests in the subject matter discussed in this manuscript. Author Contribution Masahiko Kubota: Data curation, Conceptualization, Methodology, Writing – original draft, Writing – review & editing. Seong-Yun Kim: Writing – review & editing, Supervision. Tsuyoshi Arai: Data curation. Sou Watanabe: Data curation, Tatsuya Ito: Data curation. Ryuji Nagaishi: Data curation. Acknowledgments This research was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI, Grant Number 22H00307. References Katal A, Dahiya S, Choudhury T (2023) Energy efficiency in cloud computing data centers: a survey on software technologies. 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J Radioanal Nucl Chem 331:1731–1740. 10.1007/s10967-022-08230-3 Dong HR, Ning SY, Li ZY, Xu SZ, Hu FT, Gao F, Wang YB, Chen LF, Yin XB, Fujita T, Hamza MF, Wei YZ (2024) Precise separation and efficient recovery of Pd(II) from high-level liquid waste by XAD-based adsorbents. Rare Met 43:5372–5390. 10.1007/s12598-024-02711-y Kubota M, Kim S-Y, Wu H, Arai T, Watanabe S, Sano Y, Takeuchi M (2025) Study on the development of flow sheet for the separation of MA(III) and Ln(III) fission products using two-step process with impregnated adsorbents. Prog Nucl Sci Technol. in press Ito T, kim S-Y, Nagano N, Hitomi K (2017) Effects of γ-ray irradiation on thiodiglycolamide-type extractant-impregnated adsorbents for separation of platinum group metals from high-level liquid waste. Energy Procedia 131:195–202. 10.1016/j.egypro.2017.09.427 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8747230","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":597363608,"identity":"1488610d-5ad3-4b33-b8cc-5e3a4e75e093","order_by":0,"name":"Masahiko Kubota","email":"","orcid":"","institution":"Tohoku University","correspondingAuthor":false,"prefix":"","firstName":"Masahiko","middleName":"","lastName":"Kubota","suffix":""},{"id":597363615,"identity":"ac11cec3-4b60-4903-a25e-e6c81688277c","order_by":1,"name":"Seong-Yun Kim","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDUlEQVRIie3RsUrEMBjA8e+oZErNJt+Roa+QECgI5Z7lINCpg6MgaEHoLed+Yg+fwc2xEjiXWNfCLT7AHfgEYntVOKGBG4XLf8jQ5ke/NAA+3z9OkG4NvxIAhODnYXUAoSTFwwn0xOyT4aLZ3YqHz6BOz6yADX2/ZvzWKAqTCEZvg58Rtk55aCEmPBOjEtc4LldaU9Ayh3o6SDCLeVhA0pGAijWKJlOGQtBut2JwsMUfMq1/yY2TQNOTuCdVtSPtYMZJhLXqfFmgIjy9eFnmeny/SLUsxassHGeJZnPZbItEPj7op49tPmEMtcHN5VXEcPiPtZ1gd+NdezvakQhah4Dg0/GCzV3E5/P5jqtvtkBRDJRwT7kAAAAASUVORK5CYII=","orcid":"","institution":"Tohoku University","correspondingAuthor":true,"prefix":"","firstName":"Seong-Yun","middleName":"","lastName":"Kim","suffix":""},{"id":597363616,"identity":"230c8a11-2eeb-4a5c-a077-c4555650e0b5","order_by":2,"name":"Tsuyoshi Arai","email":"","orcid":"","institution":"Shibaura Institute of Technology","correspondingAuthor":false,"prefix":"","firstName":"Tsuyoshi","middleName":"","lastName":"Arai","suffix":""},{"id":597363620,"identity":"99c2879b-ea55-45db-9727-f1283d58c447","order_by":3,"name":"Sou Watanabe","email":"","orcid":"","institution":"Japan Atomic Energy Agency","correspondingAuthor":false,"prefix":"","firstName":"Sou","middleName":"","lastName":"Watanabe","suffix":""},{"id":597363621,"identity":"9f5bb1c0-5571-4d2b-80e7-8a9c1dc88f76","order_by":4,"name":"Tatsuya Ito","email":"","orcid":"","institution":"Japan Atomic Energy Agency","correspondingAuthor":false,"prefix":"","firstName":"Tatsuya","middleName":"","lastName":"Ito","suffix":""},{"id":597363622,"identity":"85daac3a-f93c-478f-bce3-ae42c270044a","order_by":5,"name":"Ryuji Nagaishi","email":"","orcid":"","institution":"Japan Atomic Energy Agency","correspondingAuthor":false,"prefix":"","firstName":"Ryuji","middleName":"","lastName":"Nagaishi","suffix":""}],"badges":[],"createdAt":"2026-01-31 06:53:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8747230/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8747230/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":103622963,"identity":"aa04b479-a5ec-4e86-b277-8e9749ebad2e","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":48107,"visible":true,"origin":"","legend":"\u003cp\u003eChemical structure of (a) TEHDGA and (b) HONTA\u003c/p\u003e","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/969047f47c083e923bf9207e.png"},{"id":103622957,"identity":"41ba7c1f-cd4d-44ee-8311-153b4e36e522","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":140121,"visible":true,"origin":"","legend":"\u003cp\u003eCharacterization of TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents: (a) SEM micrographs; (b) TG curves (atmosphere: N\u003csub\u003e2\u003c/sub\u003e; heating rate: 1 °C min⁻\u003csup\u003e1\u003c/sup\u003e); (c) N\u003csub\u003e2\u003c/sub\u003e adsorption–desorption isotherms of XAD7-HP, TEHDGA/XAD7-HP, and HONTA/XAD7-HP adsorbents\u003c/p\u003e","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/86d5f776fea286461b54197c.png"},{"id":103622961,"identity":"588518a3-1b69-4e17-ace2-3fd9342031f7","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":274860,"visible":true,"origin":"","legend":"\u003cp\u003ePIXE spectra before and after adsorption: (a) TEHDGA/XAD7-HP adsorbent; (b) HONTA/XAD7-HP adsorbent\u003c/p\u003e","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/2f422e4e9aadcd16db501300.png"},{"id":103622958,"identity":"d3d60eb0-0633-4264-8aa3-ca62f0c4680c","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":122225,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of HNO\u003csub\u003e3\u003c/sub\u003e concentration on the adsorption of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu on the TEHDGA/XAD7-HP adsorbent. [HNO\u003csub\u003e3\u003c/sub\u003e] = 0.5–6 M; V/M = 20 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e; shaking speed = 160 rpm; shaking time = 5 h; temperature = 298 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/75f67586f5e04d72f9435949.png"},{"id":104399648,"identity":"efce278e-8709-4aae-a023-cc20927df2e6","added_by":"auto","created_at":"2026-03-11 12:07:05","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":13336,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of HNO\u003csub\u003e3\u003c/sub\u003e concentration on the adsorption of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu on the HONTA/XAD7-HP adsorbent. [HNO\u003csub\u003e3\u003c/sub\u003e] = 0.01–3 M; V/M = 20 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e; shaking speed = 160 rpm; shaking time = 1 h; temperature = 298 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/213872f68e868b136ea452b8.png"},{"id":104399161,"identity":"d6d5660a-bee0-4d3f-8d8e-7d37fbde8571","added_by":"auto","created_at":"2026-03-11 12:04:55","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":89196,"visible":true,"origin":"","legend":"\u003cp\u003eTOC analysis of TEHDGA/XAD7-HP after treatment with various HNO\u003csub\u003e3\u003c/sub\u003e concentrations. [HNO\u003csub\u003e3\u003c/sub\u003e] = 0.5–6 M; V/M = 20 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e; shaking time = 5 h; temperature = 298 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/6953402e0dcfd1b702b2bd28.png"},{"id":104398797,"identity":"8b10e782-2c44-4add-8448-dc8525e78c44","added_by":"auto","created_at":"2026-03-11 12:03:41","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":31925,"visible":true,"origin":"","legend":"\u003cp\u003eTOC analysis of HONTA/XAD7-HP after treatment with various HNO\u003csub\u003e3\u003c/sub\u003e concentrations. [HNO\u003csub\u003e3\u003c/sub\u003e] = 0.5–6 M; V/M = 20 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e; shaking time = 5 h; temperature = 298 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/1607b302b2f82738eec57dc2.png"},{"id":104399312,"identity":"629d84f4-74f6-469d-b530-93c39ebccf81","added_by":"auto","created_at":"2026-03-11 12:05:27","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":77164,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of γ-ray irradiation on the carbon retention ratio of TEHDGA/XAD7-HP\u003c/p\u003e","description":"","filename":"Onlinefloatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/9949a71949b9d8914f920ea5.png"},{"id":104399545,"identity":"9b53ba69-b893-4b53-a408-b8284f9f0add","added_by":"auto","created_at":"2026-03-11 12:06:36","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":75152,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of γ-ray irradiation on the carbon retention ratio of HONTA/XAD7-HP\u003c/p\u003e","description":"","filename":"Onlinefloatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/dd2b20422a492fa7a47664b3.png"},{"id":103622964,"identity":"224145e3-9934-4688-a852-ad710a0e8896","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":18422,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of γ-ray irradiation on the distribution coefficients of 15 metal ions on TEHDGA/XAD7-HP. [HNO\u003csub\u003e3\u003c/sub\u003e] = 2 M; V/M = 20 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e; shaking time = 5 h; temperature = 298 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage10.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/8fd2e5ece75b85b52da71363.png"},{"id":103622966,"identity":"0f75c58a-ea94-405e-bf00-799c9f4d029a","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":14041,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of γ-ray irradiation on the distribution coefficients of six metal ions on HONTA/XAD7-HP. [HNO\u003csub\u003e3\u003c/sub\u003e] = 0.01 M; V/M = 20 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e; shaking time = 5 h; temperature = 298 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/d9e23adf8779954eb12d0e07.png"},{"id":103622968,"identity":"5d007318-2055-44d9-9d55-9d473cea7aa9","added_by":"auto","created_at":"2026-02-27 19:02:47","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":172018,"visible":true,"origin":"","legend":"\u003cp\u003eChromatographic separation of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu using the TEHDGA/XAD7-HP adsorbent. Flow rate = 3 cm\u003csup\u003e3\u003c/sup\u003e min⁻\u003csup\u003e1\u003c/sup\u003e; bed height = 150 mm; column inner diameter = 10 mm; temperature = 323 K\u003c/p\u003e","description":"","filename":"Onlinefloatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/425aed477a92028c2efffb0f.png"},{"id":104399440,"identity":"e56ad119-52aa-4da8-86c2-ad7961e85858","added_by":"auto","created_at":"2026-03-11 12:06:09","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":116851,"visible":true,"origin":"","legend":"\u003cp\u003eChromatographic separation of \u003csup\u003e241\u003c/sup\u003eAm, \u003csup\u003e152\u003c/sup\u003eEu, and Ln(III) using the HONTA/XAD7-HP adsorbent. Flow rate = 1 cm\u003csup\u003e3\u003c/sup\u003e min⁻\u003csup\u003e1\u003c/sup\u003e; bed height = 100 mm; column inner diameter = 10 mm; temperature = 298 K\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e","description":"","filename":"Onlinefloatimage13.png","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/8fa227419d87e09b1edd0efb.png"},{"id":104407516,"identity":"830d5e8b-352c-43ff-b708-d14a7d84e1fc","added_by":"auto","created_at":"2026-03-11 12:38:34","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2438132,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8747230/v1/80330000-152b-4152-94d6-0222efd48af2.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Separation behavior of MA(III) from simulated high-level liquid waste using TEHDGA and HONTA impregnated XAD7-HP adsorbents","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn recent years, artificial intelligence and data centers have developed rapidly to analyze and process vast amounts of data, becoming indispensable to modern industrial activities. At the same time, society faces a growing challenge of sharply increasing electricity consumption [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. To ensure a stable power supply and mitigate environmental degradation and climate change associated with the use of fossil fuels, nuclear power generation, which can produce large amounts of electricity, is being adopted worldwide [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Spent nuclear fuel generated after power generation is reprocessed (e.g., through the PUREX process) to recover reusable materials such as uranium (U) and plutonium (Pu) while reducing waste volume. High-level radioactive liquid waste (HLLW) produced during this process contains large quantities of radioactive fission products. Among them, minor actinides (MA(III)) possess long half-lives and significantly influence the long-term radioactivity of HLLW. Reducing the volume and radioactivity of HLLW prior to final disposal therefore remains a critical challenge [\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. However, because HLLW contains large amounts of lanthanides (Ln(III)) with chemical properties similar to those of actinides, the selective separation of MA(III) from HLLW is extremely difficult[\u003cspan additionalcitationids=\"CR11 CR12\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHLLW contains a large number of fission products, making it extremely difficult to accurately separate specific nuclides. To date, various methods such as precipitation [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], solvent extraction [\u003cspan additionalcitationids=\"CR16\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e], and membrane separation [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] have been attempted to separate MA(III) from HLLW. However, these methods have drawbacks such as slow reaction rates, low capacity, and poor selectivity. In recent years, significant progress has been made in the precise separation of MA(III) using extraction chromatography [\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. This method offers several advantages, including the ability to design adsorbents using various combinations of carriers and extractants, ease of adsorbent preparation, and high selectivity. For example, various types of silica-based solid-phase adsorbents have been reported for the selective and efficient separation of MA(III) from simulated HLLW.[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eOur research group investigated a two-stage separation process using adsorbents containing N,N,N',N'-tetra(2-ethylhexyl)diglycolamide (TEHDGA) and hexaoctyl nitrilotriacetamide (HONTA). [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] The objective of this study was to evaluate the separation process using these adsorbents and achieve a two-stage separation of MA(III) and Ln(III). Co-separation evaluation of MA(III) and Ln(III) in the TEHDGA column and mutual separation evaluation of MA(III) and Ln(III) in the HONTA column are in progress. However, to establish a more effective process for the mutual separation of MA and Ln using extraction chromatography, fundamental research is necessary. In this study, we focused on Amberlite XAD7-HP as the adsorbent material. XAD7-HP is a white spherical polymer with a macroporous structure composed of cross-linked copolymers and exhibits a large specific surface area. Compared with ion exchange resins, it offers superior properties such as high chemical stability due to the absence of functional groups [\u003cspan additionalcitationids=\"CR27\" citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Although XAD7-HP has been widely used in adsorption and separation applications, studies on its use for separating Ln(III) and MA(III) from HLLW have been limited.\u003c/p\u003e \u003cp\u003eIn this study, we investigated the separation of MA(III) from simulated HLLW solutions using TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents. Specifically, the characteristics of TEHDGA/XAD7-HP and HONTA/XAD7-HP were evaluated using SEM, XRD, TG, and N\u003csub\u003e2\u003c/sub\u003e adsorption\u0026ndash;desorption analyses. Furthermore, the effects of HNO\u003csub\u003e3\u003c/sub\u003e concentration, contact time, chemical stability, and γ-ray irradiation under HNO\u003csub\u003e3\u003c/sub\u003e solution conditions were examined to assess the stability and performance of the adsorbents. Finally, column experiments were conducted using simulated HLLW solutions containing \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu to investigate their dynamic adsorption and separation behavior.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials\u003c/h2\u003e \u003cp\u003eThe TEHDGA and HONTA extractants (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) were synthesized according to previously reported procedures [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. All reagents used in this study were of analytical grade. The reagents employed to prepare the simulated high-level radioactive waste solution included lanthanum(III) nitrate hexahydrate, cerium(III) nitrate hexahydrate, neodymium(III) nitrate hexahydrate, samarium(III) nitrate hexahydrate, europium(III) nitrate hexahydrate, gadolinium(III) nitrate hexahydrate, cesium(I) nitrate, strontium(II) nitrate, barium(II) nitrate, zirconium(IV) nitrate oxide, and ammonium molybdate heptahydrate, all purchased from Kanto Chemical Co., Ltd. Nitrosylruthenium(III) nitrate solution, palladium(II) nitrate, and rhodium(III) nitrate solution were obtained from Sigma-Aldrich, while rhenium(VII) oxide was purchased from Sanwa Chemical Industries Co., Ltd. All reagents were subdivided and prepared by dissolving them in nitric acid (HNO\u003csub\u003e3\u003c/sub\u003e). Ultrapure water with a specific resistivity of at least 18.3 MΩ\u0026middot;cm was used in all experiments. The radioactive isotopes \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu were used to evaluate the adsorption and separation behavior of MA(III) and Ln(III). \u003csup\u003e241\u003c/sup\u003eAm (37 MBq) and \u003csup\u003e152\u003c/sup\u003eEu (37 MBq) were separated and diluted from their original vials to prepare a mixed solution containing \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu (\u003csup\u003e241\u003c/sup\u003eAm: 100 kBq/mL, \u003csup\u003e152\u003c/sup\u003eEu: 500 kBq/mL). The prepared mixture was spiked into the simulated high-level radioactive liquid waste solution to obtain the working solution.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePreparation of XAD7-HP impregnated adsorbents\u003c/h3\u003e\n\u003cp\u003eBefore synthesizing the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents, the porous XAD7-HP particles were washed three times with CH\u003csub\u003e3\u003c/sub\u003eOH to remove impurities from within the pores, followed by vacuum drying at 313 K for 24 h to eliminate residual methanol. The TEHDGA and HONTA extractants were completely dissolved in 300 mL of CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e as the diluent in a round-bottom flask. Subsequently, 40.0 g of thoroughly dried XAD7-HP particles were added, and the mixture was stirred at room temperature for 120 min. The extractants were then immobilized within the pores of the XAD7-HP particles by gradually removing the diluent under reduced pressure at 313 K using a rotary evaporator. Any residual CH\u003csub\u003e2\u003c/sub\u003eCl\u003csub\u003e2\u003c/sub\u003e was further removed by vacuum drying at 313 K for one day, yielding the final XAD7-HP-based adsorbents.\u003c/p\u003e\n\u003ch3\u003eCharacterization\u003c/h3\u003e\n\u003cp\u003eThe surface morphology of the samples was examined using a scanning electron microscope (SEM, TM4000Plus) equipped with an energy-dispersive X-ray analyzer. Thermogravimetric analysis (TG) was conducted using a Shimadzu DTG-60/60H instrument under an N\u003csub\u003e2\u003c/sub\u003e atmosphere (30 mL/min) at a constant heating rate of 1\u0026deg;C/min over a temperature range of 25\u0026ndash;600\u0026deg;C. For Brunauer\u0026ndash;Emmett\u0026ndash;Teller (BET) surface area analysis, the prepared samples were degassed overnight under vacuum at 70\u0026deg;C. N\u003csub\u003e2\u003c/sub\u003e adsorption\u0026ndash;desorption measurements were carried out using a Microtrac Belsorp Max analyzer under a liquid N\u003csub\u003e2\u003c/sub\u003e atmosphere (\u0026minus;\u0026thinsp;195.8\u0026deg;C) at a P/P\u003csub\u003e0\u003c/sub\u003e ratio of 0.99. X-ray photoelectron spectroscopy (XPS) was performed using a Shimadzu AXIS-ULTRA spectrometer. The behavior of TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents before and after adsorption experiments was further investigated in the solid state by photon-induced X-ray emission (PIXE) using the Microbeam MB-I system equipped with a 4.5 MeV Dynamitron accelerator at Tohoku University. The particulate target samples were irradiated with a 3 MeV proton beam focused to a spot size of 1 \u0026times; 1 \u0026micro;m\u003csup\u003e2\u003c/sup\u003e. X-rays emitted from the elements adsorbed on the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents were collected, and elemental distribution maps were generated using GeoPIXE II software.\u003c/p\u003e\n\u003ch3\u003eBatch adsorption experiments\u003c/h3\u003e\n\u003cp\u003eThe TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents were subjected to radioactive adsorption experiments with respect to \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu ions as a function of HNO\u003csub\u003e3\u003c/sub\u003e concentration at 298 K in a thermostatic shaker. The working solutions were prepared by adding stock solutions of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu to solutions containing six elements (5 mM) at different HNO\u003csub\u003e3\u003c/sub\u003e concentrations. Subsequently, 0.2 g of the TEHDGA/XAD7-HP or HONTA/XAD7-HP adsorbent was placed in a 13.5 mL glass bottle with a plastic cap and mixed with 4 mL of the prepared solution. The mixture was shaken vigorously for a predetermined period to ensure sufficient contact between the solid and liquid phases. After equilibration, the solid and aqueous phases were separated using a syringe and a nylon mesh filter. The radioactivity of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu before and after adsorption was measured by detecting γ-rays at 59.5 keV (\u003csup\u003e241\u003c/sup\u003eAm) and 122 keV (\u003csup\u003e152\u003c/sup\u003eEu), respectively, using a Canberra Ge semiconductor detector. Measurement data were analyzed using Canberra Genie 2000 software. The distribution coefficient ( \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e; cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e) for each metal ion was calculated using the following equation [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]:\u003c/p\u003e \u003cp\u003e \u003cem\u003eK\u003c/em\u003e \u003csub\u003ed\u003c/sub\u003e = \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\frac{{C}_{0}-{C}_{e}}{{C}_{e}}\\times\\:\\frac{V}{m}\\)\u003c/span\u003e\u003c/span\u003e(1)\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eC\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e represent the initial and equilibrium concentrations of the metal ions (mM), respectively, \u003cem\u003eV\u003c/em\u003e is the volume of the solution (cm\u003csup\u003e3\u003c/sup\u003e), and \u003cem\u003em\u003c/em\u003e is the mass of the TEHDGA/XAD7-HP or HONTA/XAD7-HP adsorbent (g).\u003c/p\u003e\n\u003ch3\u003eColumn separation experiments\u003c/h3\u003e\n\u003cp\u003eTo investigate the dynamic adsorption and separation behavior of \u003csup\u003e241\u003c/sup\u003eAm, \u003csup\u003e152\u003c/sup\u003eEu, and other metal ions on the adsorbents, column separation tests were conducted. The experimental setup consisted of Pyrex glass columns (10 mm Φ\u0026thinsp;\u0026times;\u0026thinsp;150 mm H for TEHDGA/XAD7-HP and 10 mm Φ\u0026thinsp;\u0026times;\u0026thinsp;100 mm H for HONTA/XAD7-HP), a hot-water circulation jacket, a metering pump, a fraction collector, and a constant-temperature hot-water circulation system. As in the batch tests, the feed solutions for column experiments were simulated high-level radioactive liquid waste (HLLW) solutions containing \u003csup\u003e241\u003c/sup\u003eAm, \u003csup\u003e152\u003c/sup\u003eEu, and lanthanide elements, prepared at specified HNO\u003csub\u003e3\u003c/sub\u003e concentrations. Prior to column packing, the fractionated TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents were immersed in pure water and degassed for 2 h to remove trapped air. The degassed adsorbents were then wet-packed into the glass columns. For column conditioning, an HNO\u003csub\u003e3\u003c/sub\u003e solution with the same concentration as the simulated HLLW feed was passed through the adsorbent-packed columns at a constant temperature. Subsequently, the simulated HLLW feed was introduced, followed by HNO\u003csub\u003e3\u003c/sub\u003e of the same concentration to elute unadsorbed components. Finally, the adsorbed components were recovered by passing pure water through the TEHDGA/XAD7-HP column and 1 M nitric acid through the HONTA/XAD7-HP column.\u003c/p\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eCharacterization of the adsorbent\u003c/h2\u003e \u003cp\u003eTo elucidate the physicochemical properties of the TEHDGA- and HONTA-impregnated adsorbents, SEM, TG, N\u003csub\u003e2\u003c/sub\u003e adsorption\u0026ndash;desorption, XPS, and PIXE analyses were conducted. SEM observations (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(a)) revealed that the surface morphology of the adsorbents was similar to that of the XAD7-HP support, with no visible extractant precipitation. This confirms that no extractant remained on the outer surface and that impregnation of the extractant occurred within the pores of the XAD7-HP support.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNext, the TG curve of the XAD7-HP adsorbent was obtained (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(b)). As the temperature increased, a significant weight loss was observed around 300\u0026deg;C. This behavior is attributed to the combustion of extractant immobilized within the XAD7-HP pores and the thermal decomposition of the XAD7-HP matrix, which consists primarily of carbon, hydrogen, and oxygen. The onset of decomposition at approximately 300\u0026deg;C demonstrates the excellent thermal stability of the XAD7-HP\u0026ndash;based impregnated adsorbents.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e(c) shows the N\u003csub\u003e2\u003c/sub\u003e adsorption\u0026ndash;desorption isotherms of the XAD7-HP support and the TEHDGA/XAD7-HP and HONTA/XAD7-HP composites. According to IUPAC classification, all samples exhibited Type IV isotherms, characteristic of mesoporous materials with cylindrical pores in the 2\u0026ndash;50 nm range [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]. After impregnation, the average pore diameter, specific surface area, and total pore volume were 8.493 nm, 150.1 m\u003csup\u003e2\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e, and 0.6374 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e for TEHDGA/XAD7-HP, and 8.229 nm, 165.6 m\u003csup\u003e2\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e, and 0.6812 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e for HONTA/XAD7-HP\u003csup\u003e2233\u003c/sup\u003e, respectively. These values were lower than those of the unmodified XAD7-HP support (8.894 nm, 554.1 m\u003csup\u003e2\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e, and 1.232 cm\u003csup\u003e3\u003c/sup\u003e g⁻\u003csup\u003e1\u003c/sup\u003e), indicating that the incorporation of TEHDGA and HONTA extractants reduced the porosity of the XAD7-HP matrix.\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e presents the X-ray spectra of the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents before and after adsorption, as determined by PIXE analysis, to investigate solid-state adsorption behavior. After contact with a 10 mM Eu(III) solution, new peaks corresponding to Eu appeared in the 5\u0026ndash;10 keV energy range. These results indicate that Eu(III) was uniformly distributed over the surfaces of both TEHDGA and HONTA adsorbents after adsorption, suggesting that the extractants were homogeneously impregnated into the XAD7-HP support during synthesis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eHNO concentration dependence of Am and Eu adsorption\u003c/h3\u003e\n\u003cp\u003eThe influence of nitric acid concentration on the adsorption behavior of minor actinide elements and coexisting metal ions on the impregnated adsorbents was examined. The results, expressed as distribution coefficients (\u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e), are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor TEHDGA/XAD7-HP, the observed trends in \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values for elements other than \u003csup\u003e241\u003c/sup\u003eAm were generally consistent with those obtained in previous batch studies using TEHDGA/SiO\u003csub\u003e2\u003c/sub\u003e\u0026ndash;P adsorbents [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. It is therefore expected that the distribution coefficient of \u003csup\u003e241\u003c/sup\u003eAm follows a similar trend.\u003c/p\u003e \u003cp\u003eIn contrast, HONTA/XAD7-HP exhibited a high distribution coefficient at low nitric acid concentrations, with \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values decreasing as the acidity increased. Moreover, the adsorption of coexisting rare earth elements resulted in a decline in the overall distribution coefficient, implying competitive adsorption between \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu. However, within the HNO\u003csub\u003e3\u003c/sub\u003e concentration range of 0.01\u0026ndash;0.1 M, a clear difference in \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values between \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu was observed. These findings suggest that column operating conditions for MA(III)/Ln(III) separation can be optimized within this acidity range. The reduction in \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e at higher HNO\u003csub\u003e3\u003c/sub\u003e concentrations is likely due to the formation of HONTA\u0026ndash;nitrate complexes, which hinder the efficient coordination and adsorption of MA(III).\u003c/p\u003e \u003cp\u003eChemical stability\u003c/p\u003e \u003cp\u003eAfter mixing the impregnated adsorbents with HNO\u003csub\u003e3\u003c/sub\u003e solution, the total organic carbon (TOC) content in the solution was measured. The eluate was analyzed to evaluate the stability of the adsorbents. Figure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows the dependence of TOC concentration in the aqueous phase on HNO\u003csub\u003e3\u003c/sub\u003e concentration. The TOC concentration exhibited a tendency to increase with increasing HNO\u003csub\u003e3\u003c/sub\u003e concentration. However, the TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents prepared in this study exhibited a leaching rate of approximately 1% at all HNO\u003csub\u003e3\u003c/sub\u003e concentrations. These results demonstrate that the adsorbents are highly stable and do not cause a significant increase in TOC concentration. Therefore, extractant loss from the adsorbents during column testing is expected to be minimal.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eEffect of γ-ray irradiation\u003c/p\u003e \u003cp\u003eUnder actual processing conditions, adsorbents are exposed to radiation, which may lead to degradation of adsorption performance through decomposition of organic extractants, leaching of degradation products, or weakening of the organic matrix.\u003c/p\u003e \u003cp\u003eTo investigate radiation-induced degradation, the carbon leakage rate from the adsorbents was determined from TOC values in the liquid phase of gamma-irradiated samples obtained at various absorbed doses using a Co-60 source. Solid\u0026ndash;liquid ratios of 20 and 1.5 were employed, corresponding to batch adsorption and column separation conditions, respectively [\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. Specifically, 0.2 g of adsorbent was contacted with 4.0 mL (solid\u0026ndash;liquid ratio 20) or 0.3 mL (solid\u0026ndash;liquid ratio 1.5) of 2 M HNO\u003csub\u003e3\u003c/sub\u003e solution.\u003c/p\u003e \u003cp\u003eAs shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and \u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e, no significant carbon leakage from the XAD7-HP particles was observed after γ-ray irradiation up to approximately 700 kGy. Within this dose range, no abrupt increase in carbon leakage was detected, indicating minimal irradiation-induced structural deterioration.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigures \u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e and \u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e present the effect of radiation-induced extractant decomposition on the adsorption performance of TEHDGA/XAD7-HP and HONTA/XAD7-HP for various metal ions. A gradual decrease in adsorption capacity was observed with increasing absorbed dose up to 700 kGy, suggesting that extractant decomposition by γ-radiation led to reduced adsorption performance. For Pd(II), a pronounced decrease in the distribution coefficient was noted up to 200 kGy. Conversely, Zr exhibited a gradual increase in adsorption rate with increasing absorbed dose, which may be attributed to the formation of radiation-induced decomposition products with enhanced affinity toward Zr.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eColumn Experiment\u003c/h2\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003e presents the results of column experiments conducted using the TEHDGA/XAD7-HP adsorbent at a flow rate of 3 mL min⁻\u003csup\u003e1\u003c/sup\u003e. Initially, 7 M nitric acid solution was introduced as the eluent to remove elements other than \u003csup\u003e241\u003c/sup\u003eAm, Ln(III), and Zr. Non-adsorbed components were rapidly eluted, whereas the adsorbed components were retained on the impregnated adsorbent. Subsequently, distilled water was introduced to separate and recover the target elements\u0026mdash;\u003csup\u003e241\u003c/sup\u003eAm, \u003csup\u003e152\u003c/sup\u003eEu, and Ln(III)\u0026mdash;that had been retained on the adsorbent. A mixed solution containing minor actinide elements (including \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu) and lanthanide elements was successfully recovered. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the recovery ratios for each element obtained from the column experiments. Nearly all elements exhibited high recovery efficiencies. In the case of Zr, residual quantities remaining within the column could likely be recovered by passing an ethylenediaminetetraacetic acid (EDTA) solution through the system.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNext, Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e shows the chromatographic separation results obtained using the HONTA/XAD7-HP adsorbent at a flow rate of 1 mL min⁻\u003csup\u003e1\u003c/sup\u003e. After introducing the feed and elution solutions, non-adsorbed components, including Ln(III) and \u003csup\u003e152\u003c/sup\u003eEu, were rapidly eluted. Subsequently, \u003csup\u003e241\u003c/sup\u003eAm was eluted, confirming that the HONTA/XAD7-HP adsorbent possesses the potential to selectively separate \u003csup\u003e241\u003c/sup\u003eAm from solutions containing both \u003csup\u003e241\u003c/sup\u003eAm and Ln(III). The recovery ratios for all analyzed elements were 100% (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), and no detectable residual material remained within the column. However, the peaks corresponding to Ln(III) and MA(III) were closely spaced, indicating that the adsorption\u0026ndash;desorption reactions between metal ions and the extractant proceed relatively slowly. Therefore, longer contact times or optimization of the flow rate and column dimensions\u0026mdash;particularly increasing column length\u0026mdash;may be required to achieve complete separation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRecovery ratios of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu using the TEHDGA-packed column in the presence of Ln elements\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRecovery ratio (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRecovery ratio (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eRecovery ratio (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csup\u003e241\u003c/sup\u003eAm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRh\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csup\u003e152\u003c/sup\u003eEu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCs\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eZr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e85.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e99.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSr\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eBa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eRe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eRu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRecovery ratios of \u003csup\u003e241\u003c/sup\u003eAm and \u003csup\u003e152\u003c/sup\u003eEu using the HONTA-packed column in the presence of Ln elements\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eRecovery ratio (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRecovery ratio (%)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csup\u003e241\u003c/sup\u003eAm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003csup\u003e152\u003c/sup\u003eEu\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCe\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNd\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eA novel adsorption and separation process employing TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents impregnated onto porous XAD7-HP supports was successfully developed. The effects of HNO\u003csub\u003e3\u003c/sub\u003e concentration on the adsorption and column separation behaviors of \u003csup\u003e241\u003c/sup\u003eAm(III) and \u003csup\u003e152\u003c/sup\u003eEu(III) from HNO\u003csub\u003e3\u003c/sub\u003e solutions were systematically investigated. The adsorption capacities of Am(III) and Eu(III) on HONTA/SiO\u003csub\u003e2\u003c/sub\u003e\u0026ndash;P decreased with increasing HNO\u003csub\u003e3\u003c/sub\u003e concentration; however, distinct differences in the \u003cem\u003eK\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e values of Am(III) and Eu(III) were observed at lower acid concentrations. PIXE analysis after batch testing confirmed that the TEHDGA and HONTA extractants were uniformly impregnated into and retained within the pores of the XAD7-HP matrix. The prepared adsorbents exhibited excellent chemical stability and radiation resistance. Column separation experiments using a combination of TEHDGA/XAD7-HP and HONTA/XAD7-HP carriers effectively achieved the separation of Am(III) and Eu(III) from HNO\u003csub\u003e3\u003c/sub\u003e solutions. Although coexisting elements influenced the separation behavior, varying the nitric acid concentration in the eluent enabled efficient separation of Am(III) from the various Ln(III) ions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflict of interest\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no conflicts of interest or involvement with any organization or entity having financial or non-financial interests in the subject matter discussed in this manuscript.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMasahiko Kubota: Data curation, Conceptualization, Methodology, Writing \u0026ndash; original draft, Writing \u0026ndash; review \u0026amp; editing. Seong-Yun Kim: Writing \u0026ndash; review \u0026amp; editing, Supervision. Tsuyoshi Arai: Data curation. Sou Watanabe: Data curation, Tatsuya Ito: Data curation. Ryuji Nagaishi: Data curation.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eThis research was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI, Grant Number 22H00307.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKatal A, Dahiya S, Choudhury T (2023) Energy efficiency in cloud computing data centers: a survey on software technologies. 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Energy Procedia 131:195\u0026ndash;202. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.egypro.2017.09.427\u003c/span\u003e\u003cspan address=\"10.1016/j.egypro.2017.09.427\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Minor actinide, Extraction chromatography, TEHDGA, HONTA, XAD7-HP","lastPublishedDoi":"10.21203/rs.3.rs-8747230/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8747230/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eTo achieve selective adsorption and separation of minor actinides (MA(III)) from lanthanides (Ln(III)), impregnated adsorbents were prepared by loading Amberlite XAD7-HP particles with tetra-2-ethylhexyl diglycolamide (TEHDGA) and hexaoctyl nitrilotriacetamide (HONTA), respectively. Batch experiments were performed to evaluate the adsorption characteristics of TEHDGA/XAD7-HP and HONTA/XAD7-HP adsorbents toward MA(III) and simulated fission products in HNO\u003csub\u003e3\u003c/sub\u003e solutions. Particle-induced X-ray emission analysis confirmed the uniform distribution of Eu(III) on the adsorbent surface. This study establishes a process for separating MA(III) using TEHDGA/XAD7-HP and HONTA/XAD7-HP column systems.\u003c/p\u003e","manuscriptTitle":"Separation behavior of MA(III) from simulated high-level liquid waste using TEHDGA and HONTA impregnated XAD7-HP adsorbents","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-02-27 19:02:42","doi":"10.21203/rs.3.rs-8747230/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9084837a-fa4c-470d-be2f-5dac89b70e85","owner":[],"postedDate":"February 27th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-01T06:38:47+00:00","versionOfRecord":[],"versionCreatedAt":"2026-02-27 19:02:42","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8747230","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8747230","identity":"rs-8747230","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}