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Journal Articles

Sorption mechanism of europium(III) onto metakaolin-based geopolymers

Yildirim, A. C.*; Mei, H.*; Toda, Kanako*; Aoyagi, Noboru; Saito, Takumi*

Applied Clay Science, 274, p.107853_1 - 107853_9, 2025/09

 Times Cited Count:0 Percentile:0.00(Chemistry, Physical)

Journal Articles

Sorption of Cs$$^{+}$$ and Eu$$^{3+}$$ onto coherent and melange-type pre-neogene sedimentary rocks

Hou, L.*; Toda, Kanako*; Mei, H.; Aoyagi, Noboru; Saito, Takumi*

Journal of Nuclear Science and Technology, 61(11), p.1488 - 1498, 2024/11

 Times Cited Count:2 Percentile:75.80(Nuclear Science & Technology)

Journal Articles

Trivalent lanthanide sorption onto illite in the presence of carbonate; A Study combining thermodynamic sorption modeling, time-resolved laser fluorescence spectroscopy, and parallel factor analysis

Sugiura, Yuki; Ishidera, Takamitsu; Aoyagi, Noboru; Mei, H.; Saito, Takumi*; Tachi, Yukio

Applied Clay Science, 258, p.107476_1 - 107476_10, 2024/09

 Times Cited Count:2 Percentile:69.91(Chemistry, Physical)

Journal Articles

Application of diffusive gradients in thin films (DGT) for the dynamic speciation of radioactive cesium in Fukushima Prefecture, Japan

Tanaka, Takuro*; Fukuoka, Masafumi*; Toda, Kanako*; Nakanishi, Takahiro; Terashima, Motoki; Fujiwara, Kenso; Niwano, Yuma*; Kato, Hiroaki*; Kobayashi, Natsuko*; Tanoi, Keitaro*; et al.

ACS ES&T Water (Internet), 4(8), p.3579 - 3586, 2024/08

Journal Articles

Comprehensive extraction study using $$N,N$$-dioctylthiodiglycolamic acid; Effect of S donor on metal extraction

Shimojo, Kojiro; Fujiwara, Iori*; Saito, Takumi*; Oshima, Tatsuya*

Analytical Sciences, 40(8), p.1429 - 1436, 2024/08

 Times Cited Count:0 Percentile:0.00(Chemistry, Analytical)

Extraction ability of $$N,N$$-dioctylthiodiglycolamic acid (T-DODGAA), a soft-base sulfur donor ligand with an amide group and a carboxylic acid connected by a thioether chain, for 56 metal ions have been comprehensively investigated and compared with that of N,N-dioctyldiglycolamic acid (DODGAA) with an etheric oxygen atom, a hard-base donor. The p$$K_{a}$$ of the thiodiglycolamic acid framework was determined to be 3.71 $$pm$$ 0.06 in water (0.1 M LiCl, 25$$^{circ}$$C ) by potentiometric titration, indicating that T-DODGAA is a slightly weaker acid than DODGAA (p$$K_{a}$$ = 3.54 $$pm$$ 0.03). T-DODGAA can quantitatively extract various metal ions from the 56 metal ions through a proton-exchange reaction. T-DODGAA provided higher extraction performance than DODGAA for Hf(IV), Cr(III), Fe(III), Ni(II), Cu(II), Pd(II), Ag(I), Au(III), Hg(II), Al(III), and Ga(III), especially for soft metal ions. Furthermore, to demonstrate the practical feasibility of T-DODGAA for hydrometallurgy and metal recycling, we performed selective separation tests of rare metal ions such as Sc(III), Ni(II), Co(II), Pd(II), Au(III), In(III), and Ga(II) in metal-mixed extraction systems.

Journal Articles

Globular pattern formation of hierarchical ceria nanoarchitectures

Aoyagi, Noboru; Motokawa, Ryuhei; Okumura, Masahiko; Ueda, Yuki; Saito, Takumi*; Nishitsuji, Shotaro*; Taguchi, Tomitsugu*; Yomogida, Takumi; Sazaki, Gen*; Ikeda, Atsushi

Communications Chemistry (Internet), 7, p.128_1 - 128_13, 2024/06

 Times Cited Count:0 Percentile:0.00(Chemistry, Multidisciplinary)

Journal Articles

"Invisible" radioactive cesium atoms revealed; Pollucite inclusion in cesium-rich microparticles (CsMPs) from the Fukushima Daiichi Nuclear Power Plant

Miyazaki, Kanako*; Takehara, Masato*; Minomo, Kenta*; Horie, Kenji*; Takehara, Mami*; Yamasaki, Shinya*; Saito, Takumi*; Onuki, Toshihiko*; Takano, Masahide; Shiotsu, Hiroyuki; et al.

Journal of Hazardous Materials, 470(15), p.134104_1 - 134104_11, 2024/05

 Times Cited Count:1 Percentile:31.14(Engineering, Environmental)

Journal Articles

U(VI) sorption on illite in the presence of carbonate studied by cryogenic time-resolved laser fluorescence spectroscopy and parallel factor analysis

Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Tanaka, Kazuya; Sugiura, Yuki; Tachi, Yukio

Applied Geochemistry, 162, p.105926_1 - 105926_8, 2024/02

 Times Cited Count:2 Percentile:64.73(Geochemistry & Geophysics)

Journal Articles

Origin of dissolved organic matter in deep groundwater of marine deposits and its implication for metal binding

Saito, Takumi*; Nishi, Shusaku*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya

ACS ES&T Water (Internet), 3(12), p.4103 - 4112, 2023/12

Journal Articles

Heterogeneous aggregation of humic acids studied by small-angle neutron and X-ray scattering

Saito, Takumi*; Motokawa, Ryuhei; Okubo, Takahiro*; Miura, Daisuke*; Kumada, Takayuki

Environmental Science & Technology, 57(26), p.9802 - 9810, 2023/07

 Times Cited Count:1 Percentile:9.13(Engineering, Environmental)

Journal Articles

Hydration states of europium(III) adsorbed on silicas with nano-sized pores

Murota, Kento*; Aoyagi, Noboru; Mei, H.; Saito, Takumi*

Applied Geochemistry, 152, p.105620_1 - 105620_11, 2023/05

 Times Cited Count:5 Percentile:63.49(Geochemistry & Geophysics)

Journal Articles

Lanthanide and actinide ion complexes containing organic ligands investigated by surface-enhanced infrared absorption spectroscopy

Hirata, Sakiko*; Kusaka, Ryoji; Meiji, Shogo*; Tamekuni, Seita*; Okudera, Kosuke*; Hamada, Shoken*; Sakamoto, Chihiro*; Honda, Takumi*; Matsushita, Kosuke*; Muramatsu, Satoru*; et al.

Inorganic Chemistry, 62(1), p.474 - 486, 2023/01

 Times Cited Count:3 Percentile:27.89(Chemistry, Inorganic & Nuclear)

Journal Articles

High-temperature gaseous reaction of cesium with siliceous thermal insulation; The Potential implication to the provenance of enigmatic Fukushima cesium-bearing material

Rizaal, M.; Nakajima, Kunihisa; Saito, Takumi*; Osaka, Masahiko; Okamoto, Koji*

ACS Omega (Internet), 7(33), p.29326 - 29336, 2022/08

 Times Cited Count:5 Percentile:35.08(Chemistry, Multidisciplinary)

Journal Articles

Current status of Geological disposal by "all-Japan" activities, 6; Post-closure safety assessment (2)

Tachi, Yukio; Saito, Takumi*; Kirishima, Akira*

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 64(5), p.290 - 295, 2022/05

no abstracts in English

Journal Articles

Volatilization of B$$_{4}$$C control rods in Fukushima Daiichi nuclear reactors during meltdown; B-Li isotopic signatures in cesium-rich microparticles

Fueda, Kazuki*; Takami, Ryu*; Minomo, Kenta*; Morooka, Kazuya*; Horie, Kenji*; Takehara, Mami*; Yamasaki, Shinya*; Saito, Takumi*; Shiotsu, Hiroyuki; Onuki, Toshihiko*; et al.

Journal of Hazardous Materials, 428, p.128214_1 - 128214_10, 2022/04

 Times Cited Count:12 Percentile:66.41(Engineering, Environmental)

Journal Articles

Dispersive XAFS Study on the Laser-Induced Reduction of a Rh$$^{3+}$$ ion complex; Presence of a Rh$$^{+}$$ Intermediate in Direct Photoreduction

Saeki, Morihisa*; Matsumura, Daiju; Nakanishi, Ryuzo*; Yomogida, Takumi; Tsuji, Takuya; Saito, Hiroyuki*; Oba, Hironori*

Journal of Physical Chemistry C, 126(12), p.5607 - 5616, 2022/03

 Times Cited Count:2 Percentile:12.33(Chemistry, Physical)

The reaction mechanism of the direct photoreduction of a Rh$$^{3+}$$ ion complex to a Rh$$^{0}$$ species induced by pulsed ultraviolet laser irradiation was studied using dispersive X-ray absorption fine structure (DXAFS) spectroscopy. The time-resolved X-ray absorption near edge structure (XANES) showed the absence of isosbestic points and suggested that more than two Rh$$^{n+}$$ species contribute toward the direct photoreduction of Rh$$^{3+}$$. Analysis of the time-resolved XANES data by singular value deposition showed that the direct photoreduction involves three Rh$$^{n+}$$ species. Multivariate curve resolution by alternating least-squares analysis (MCR-ALS) of the time-resolved XANES data gave pure spectra and concentration profiles of the three Rh$$^{n+}$$ species. The Rh$$^{n+}$$ species were assigned to Rh$$^{3+}$$, Rh$$^{+}$$, and Rh$$^{0}$$ species based on the features of the pure XANES spectra. The concentration profiles suggested that the direct photoreduction proceeds in the order of Rh$$^{3+}$$ $$rightarrow$$ Rh$$^{+}$$ $$rightarrow$$ Rh$$^{0}$$. A reaction mechanism, which was proposed involving photoreductions of Rh$$^{3+}$$ and Rh$$^{+}$$, photoinduced autocatalytic reductions of Rh$$^{3+}$$ and Rh$$^{+}$$, and photooxidation of Rh$$^{+}$$, well reproduced the concentration profiles of three Rh$$^{n+}$$ species.

Journal Articles

Uranium (VI) sorption on illite under varying carbonate concentrations; Batch experiments, modeling, and cryogenic time-resolved laser fluorescence spectroscopy study

Mei, H.; Aoyagi, Noboru; Saito, Takumi*; Kozai, Naofumi; Sugiura, Yuki; Tachi, Yukio

Applied Geochemistry, 136, p.105178_1 - 105178_8, 2022/01

 Times Cited Count:21 Percentile:89.42(Geochemistry & Geophysics)

Journal Articles

Stoichiometry between humate unit molecules and metal ions in supramolecular assembly induced by Cu$$^{2+}$$ and Tb$$^{3+}$$ measured by gel electrophoresis techniques

Nakano, Sumika*; Marumo, Kazuki*; Kazami, Rintaro*; Saito, Takumi*; Haraga, Tomoko; Tasaki-Handa, Yuiko*; Saito, Shingo*

Environmental Science & Technology, 55(22), p.15172 - 15180, 2021/11

 Times Cited Count:5 Percentile:21.63(Engineering, Environmental)

Humic acid (HA) can strongly complex with metal ions to form a supramolecular assembly via coordination binding. However, determining the supramolecular size distribution and stoichiometry between small HA unit molecules constituting HA supramolecule and metal ions has proven to be challenging. Here, we investigated the changes in the size distributions of HAs induced by Cu$$^{2+}$$ and Tb$$^{3+}$$ ions using a unique polyacrylamide gel electrophoresis (PAGE) for the separation and quantification of HA complexes and metal ions bound, followed by UV-Vis spectroscopy and EEM-PARAFAC. It was found that the supramolecular behaviors of Cu$$^{2+}$$ and Tb$$^{3+}$$ complexes with HA collected from peat and deep groundwater (HHA) differed. Our results suggest that this supramolecular stoichiometry is related to the abundance of sulfur atoms in the elemental composition of HHA. Our results provide new insights into HA supramolecules formed via metal complexation.

Journal Articles

Microparticles with diverse sizes and morphologies from mechanical and laser cutting of fuel debris simulants and geopolymer as a covering material

Zhou, Q.*; Saito, Takumi*; Suzuki, Seiya; Yano, Kimihiko; Suzuki, Shunichi*

Journal of Nuclear Science and Technology, 58(4), p.461 - 472, 2021/04

 Times Cited Count:9 Percentile:70.62(Nuclear Science & Technology)

Journal Articles

Application of an augmentation method to MCR-ALS analysis for XAFS and Raman data matrices in the structural change of isopolymolybdates

Saeki, Morihisa*; Yomogida, Takumi; Matsumura, Daiju; Saito, Takumi*; Nakanishi, Ryuzo*; Tsuji, Takuya; Oba, Hironori*

Analytical Sciences, 36(11), p.1371 - 1378, 2020/11

 Times Cited Count:6 Percentile:20.69(Chemistry, Analytical)

We measured X-ray absorption fine structure (XAFS) and Raman spectra of isopolymolybdates(VI) in HNO$$_{3}$$ solution (0.15- 4.0 M), which change their geometries depending on acid concentration, and performed simultaneous resolution of the XAFS and Raman data using a multivariate curve resolution by alternating least-squares (MCR-ALS) analysis. In iterative ALS optimization, initial data matrices were prepared by two different methods. The MCR-ALS result of single XAFS data matrix shows large dependence on the preparation method of the initial data matrices. The MCR-ALS result of an augmented matrix of Raman and XAFS data has little dependence on the initial data matrices. It indicates that the augmentation method effectively improves the rotation ambiguities in the MCR-ALS analysis of the XAFS data. Based on the model fitting of the pure EXAFS oscillations, we revealed the change of [Mo$$_{36}$$O$$_{112}$$(H$$_{2}$$O)$$_{16}$$]$$^{2+}$$ $$rightarrow $$ [Mo$$_{2}$$O$$_{5}$$(H$$_{2}$$O)$$_{6}$$]$$^{2+}$$ $$rightarrow $$ [HMoO$$_{3}$$(H$$_{2}$$O)$$_{3}$$]$$^{+}$$ in the highly concentrated HNO$$_{3}$$ solution.

151 (Records 1-20 displayed on this page)