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Journal Articles

Zeolite-assisted radiolysis of aromatic chlorides mitigating influence of coexisting ions in water matrix

Kumagai, Yuta; Kimura, Atsushi*; Taguchi, Mitsumasa*; Watanabe, Masayuki

Radiation Physics and Chemistry, 191, p.109831_1 - 109831_8, 2022/02

https://doi.org/10.1016/j.radphyschem.2021.109831

Times Cited Count：0 Percentile：0.01(Chemistry, Physical)

In this study, we investigated and compared the effects of a high-silica zeolite (HMOR) on the radiation-induced degradation of three aromatic chlorides, 2-chlorophenol (2-ClPh), 2-chloroaniline (2-ClAn), and 2-chlorobenzoic acid (2-ClBA), in order to examine its potential to reduce the influence of ions in water matrix in the irradiation treatment of water-soluble organic compounds. In the presence of ions reactive to radicals, the degradation of 2-ClPh in water was inhibited, but the combined use of HMOR much improved the degradation yield. This improvement was attributed to high performance of HMOR in adsorption of 2-ClPh. Similarly, HMOR was effective for adsorption of 2-ClAn and facilitated the 2-ClAn degradation by irradiation. In contrast, HMOR was poor at adsorption of 2-ClBA and consistently the degradation of 2-ClBA in the water-HMOR mixture was inhibited by the radical scavenger. These results demonstrate that HMOR can mitigate the influence of radical scavengers in water.

Journal Articles

Treatment of pharmaceuticals/antibiotics in wastewater by combination of zeolite adsorbent with ionizing radiation

Taguchi, Mitsumasa*; Kumagai, Yuta; Kimura, Atsushi*

IAEA-TECDOC-1855, p.106 - 116, 2018/00

The technology for the decomposition of trace amounts of halogenated pharmaceuticals/antibiotics was developed in wastewater by use of the combination method of zeolite adsorbent and ionizing radiation. HMOR, a hydrophobic high-silica mordenite-type zeolite, was employed to concentrate 2-chlorophenol (2-ClPh) as a simple model of halogenated pharmaceuticals/antibiotics. HMOR adsorbed above 99% of 2-ClPh from dilute aqueous solutions. The yield of Cl $^{-}$ production in HMOR mixture corresponded to the aqueous solution containing 10 fold higher concentration of dissolved 2-ClPh. Clofibrate and triclosan, one of chlorinated pharmaceuticals/antibiotics, in real wastewater were treated by use of the combination method of HMOR and ionizing radiation. Production yield of Cl $^{-}$ by use of the adsorbent was about twice higher than that in aqueous solution, and HMOR was contributed for effective reduction of chlorinated pharmaceuticals/antibiotics in real wastewater.

Journal Articles

Modern radiation chemistry (Applications), 18; Radiation chemistry at solid/water interfaces

Kumagai, Yuta

Radioisotopes, 66(11), p.537 - 541, 2017/11

https://doi.org/10.3769/radioisotopes.66.537

Radiation effects on the mixtures of inorganic oxides and water have been investigated for understanding radiation chemistry in solid-liquid systems. A number of studies revealed that energy deposition on solid phase stimulates reactions at the interface. This energy/charge transfer has been demonstrated by experiments to affect early stage of the radiation-induced reaction. However, the interfacial reactions subsequent to the energy/charge transfer require further studies. Here, we will see gaps between the basic understanding on the early stage and radiation effects in solid-liquid systems connected to applications, taking zeolite/water and uranium oxide/water interfaces for examples. Understanding of the interfacial reactions subsequent to the energy/charge transfer would bridge the gaps and enable to predict the radiation effects in applications.

Journal Articles

Hydrogen production by -ray irradiation from different types of zeolites in aqueous solution

Kumagai, Yuta; Kimura, Atsushi*; Taguchi, Mitsumasa*; Watanabe, Masayuki

Journal of Physical Chemistry C, 121(34), p.18525 - 18533, 2017/08

https://doi.org/10.1021/acs.jpcc.7b03532

Times Cited Count：7 Percentile：26.48(Chemistry, Physical)

H $_{2}$ production by irradiation of zeolite-water mixtures was studied, to investigate effect of zeolites in the reaction process for H $_{2}$ . Four different types of zeolites were examined comparatively under anoxic and under aerated conditions. High production yields of H $_{2}$ were observed for the zeolites of high Al contents at low water fraction and under anoxic condition, compared to zeolites having lower Al contents. A comparison of the H $_{2}$ yields in connection with chemical analysis of the zeolites suggests that extraframework Al species in the zeolites are involved in a reaction pathway for H $_{2}$ . Meanwhile, under aerated condition and at high mixing ratio of water, the difference in H $_{2}$ yield among the zeolites was suppressed and the yields of H $_{2}$ were lower than those under anoxic condition probably due to H $_{2}$ O $_{2}$ produced by water radiolysis. The comparable H $_{2}$ yields suggest another reaction pathway for H $_{2}$ which is less dependent on the structure and composition of the zeolites.

Journal Articles

Fine dispersion of Pt $_{4-5}$ subnanoclusters and Pt single atoms over porous carbon supports and their structural analyses with X-ray absorption spectroscopy

Itoi, Hiroyuki*; Nishihara, Hirotomo*; Kobayashi, Shunsuke*; Ittisanronnachai, S.*; Ishii, Takafumi*; Berenguer, R.*; Ito, Masashi*; Matsumura, Daiju; Kyotani, Takashi*

Journal of Physical Chemistry C, 121(14), p.7892 - 7902, 2017/04

https://doi.org/10.1021/acs.jpcc.7b00422

Times Cited Count：31 Percentile：71.76(Chemistry, Physical)

Journal Articles

Localized corrosion behavior of stainless steel in the diluted artificial sea-water contacted with zeolite under -ray irradiation

Kato, Chiaki; Sato, Tomonori; Nakano, Junichi; Ueno, Fumiyoshi; Yamagishi, Isao; Yamamoto, Masahiro

Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(3), p.181 - 188, 2015/09

https://doi.org/10.3327/taesj.J14.030

In relation to the consideration for long-term storage of spent Cs adsorption vessels containing zeolites in the Fukushima Daiichi Nuclear Power Station, corrosion of the vessel material in the spent Cs adsorption vessel is one of important issues. We performed electrochemical tests of stainless steel (SUS 316L) in the zeolites containing artificial seawater under -ray irradiation. The spontaneous potential ( $E_{rm SP}$ ) and critical pitting potential ( $V_{rm c}$ ), of SUS 316L were measured to understand the corrosion resistance of the stainless steel in this study. The rest potential of the stainless steel increased with increasing time after -ray irradiation. The $E_{rm SP}$ , defined as the steady rest potential, increased with increasing dose rate, while increasing $E_{rm SP}$ was suppressed by contact with the zeolites. Concentration of H $_{2}$ O $_{2}$ in bulk water increased with increasing dose rate. The concentration increasing was suppressed by contact with the zeolites due to decomposition of H $_{2}$ O $_{2}$ . There was good relationship between $E_{rm SP}$ and the concentration of H $_{2}$ O $_{2}$ . The $V_{rm c}$ of SUS 316L contacted with the zeolites decreased with increasing Cl $^{-}$ ion concentration and is slightly smaller than the $V_{rm c}$ in the bulk water. The contact with the zeolites causes the suppressant of increasing $E_{rm SP}$ under the irradiation. The contact with the zeolite can reduce probability in the localized corrosion for SUS 316L.

Journal Articles

Effect of zeolites on the corrosion potential of type 316L stainless steel in diluted artificial sea water under gamma-ray irradiation

Kato, Chiaki; Sato, Tomonori; Ueno, Fumiyoshi; Yamagishi, Isao; Yamamoto, Masahiro

Zairyo To Kankyo 2015 Koenshu (CD-ROM), p.83 - 86, 2015/05

In relation to the consideration for long-term storage of spent Cs adsorption vessels containing zeolites in the Fukushima Daiichi Nuclear Power Station, corrosion of the vessel material in the spent Cs adsorption vessel is one of important issues. We performed electrochemical tests of stainless steel (SUS 316L) in the zeolites containing artificial seawater under gamma-ray irradiation. The spontaneous potential (ESP) and critical pitting potential (VC), of SUS316L were measured to understand the corrosion resistance of the stainless steel in this study. The rest potential of the stainless steel increased with increasing time after gamma-ray irradiation. The ESP, defined as the steady rest potential, increased with increasing dose rate, while increasing ESP was suppressed by contact with the zeolites. Concentration of H $_{2}$ O $_{2}$ in bulk water increased with increasing dose rate. The concentration increasing was suppressed by contact with the zeolites due to decomposition of H $_{2}$ O $_{2}$ . There was good relationship between ESP and the concentration of H $_{2}$ O $_{2}$ . The VC of SUS316L contacted with the zeolites decreased with increasing Cl $^{-}$ ion concentration and is slightly smaller than the VC in the bulk water. The contact with the zeolites causes the suppressant of increasing ESP under the irradiation. The contact with the zeolites can reduce probability in the localized corrosion for SUS316L.

Journal Articles

Treatment of highly contaminated water with highly selective adsorbents mainly composed of zeolites

Mimura, Hitoshi*; Yamagishi, Isao

Zeoraito, 31(4), p.115 - 124, 2014/12

Massive tsunami caused by the Great East Japan Earthquake attacked the Fukushima Daiichi Nuclear Power Plant and caused the nuclear accident of level 7 to overturn the safety myth of nuclear power generation. The domestic worst accident does not yet reach the convergence, and many inhabitants around the power plant are forced to double pains of earthquake disaster and nuclear accident. At present, large amounts of high-activity-level water over 500,000 tons are stored in Fukushima NPP-1 site, which is a serious obstacle to take measures for the nuclear accident. For the decontamination of high-activity-level water containing seawater, the circulating injection cooling system using packed columns with inorganic ion-exchangers is operated and the cold shutdown is accomplished. However, the advancement of operating system and the safety management of secondary solid wastes are very important subject. In this paper, the adsorption properties and solidification characteristics are compared for Cs and Sr selective adsorbents mainly composed of zeolites and the enhancement of adsorption properties are reported. Especially, naturally occurring zeolites abundant in Japan have high selectivity towards Cs, and also have excellent functions of gas trapping and self sintering for stable solidification. Zeolites are thus expected for the treatment and disposal of contaminated water in future. This paper also reports the present situation of safety management of solid wastes and the development of stable solidification methods, and summarizes the future subjects considering the safety disposal.

Journal Articles

Estimation of the cesium concentration in spent zeolite vessels

Morita, Keisuke; Yamagishi, Isao; Nishihara, Kenji; Tsubata, Yasuhiro

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 11 Pages, 2014/10

Journal Articles

Revaluation of hydrogen generation by water radiolysis in SDS vessels at TMI-2 accident

Nagaishi, Ryuji; Morita, Keisuke; Yamagishi, Isao; Hino, Ryutaro; Ogawa, Toru

Proceedings of 2014 Nuclear Plant Chemistry Conference (NPC 2014) (USB Flash Drive), 9 Pages, 2014/10

BB2014-1745.pdf:0.92MB

Two years after Three Mile Island Unit 2 (TMI-2) loss-of-coolant accident, radioactive contaminated water has been processed by Submerged Demineralizer System (SDS) with two types of zeolite adsorbents to remove radioactive nuclides. During and after the process, adsorption amount and distribution of nuclides on the zeolites, residual water content and thermal conductivity in the SDS vessels have been measured or estimated for verification of safety in the process, subsequent transportation and disposal. Hydrogen generation has been also evaluated mainly by direct monitoring in the large-scale of vessel after the process. In this work, the revaluation of hydrogen generation was demonstrated on the basis of the open information of vessel, and the latest experimental data obtained in adsorption and radiolysis occurring in small-scale of zeolite-water mixtures. As a result, the evaluated data was found to be comparable with the reported data obtained in the large-scale of real vessel.

Journal Articles

Application of pressure swing adsorption to water detritiation process

Iwai, Yasunori; Yamanishi, Toshihiko; Nishi, Masataka; Suzuki, Yutaka*; Kurita, Koichi*; Shimazaki, Masanori*

Journal of Nuclear Science and Technology, 42(6), p.566 - 572, 2005/06

https://doi.org/10.3327/jnst.42.566

Times Cited Count：6 Percentile：40.47(Nuclear Science & Technology)

Pressure swing adsorption has been studied as a new water processing method for a future fusion power plant which will have a large amount of tritiated water to be processed. A series of adsorption and dehydration experiments was carried out for a typical adsorbent of NaX zeolite and it was clearly observed that break through time differs in H $_{2}$ O and HTO, that is, it is certain that NaX zeolite can separate into the tritium concentrated water and the tritium reduced water. The quick dehydration is attained by decompression and purge gas flowing. It was observed that a part of the water released by decompression was transferred by the purge gas, and the rest water was adsorbed on the adsorbent again and was gradually released by the diffusion. It is demonstrated that enlargement of pressure difference between adsorption and dehydration is effective to obtain high dehydration ratio. Furthermore, it was also verified that enough vapor removal capacity of purge gas is quite necessary to obtain high dehydration ratio.

Journal Articles

In-situ XAFS analysis of Y zeolite-supported Rh catalysts during high-pressure hydrogenation of CO $_{2}$

Bando, Kyoko*; Saito, Takeru; Sato, Koichi*; Tanaka, Tomoaki*; Dumeignil, F.*; Imamura, Motoyasu*; Matsubayashi, Nobuyuki*; Shimada, Hiromichi*

Topics in Catalysis, 18(1-2), p.59 - 65, 2002/01

no abstracts in English

JAEA Reports

Natural analogue of alteration of bentonite contacting with concrete

Imai, Jun*

JNC TJ8400 2000-008, 196 Pages, 2000/02

JNC-TJ8400-2000-008.pdf:25.25MB

The objective of this research is to make clear long-term alteration processes of bentonite contacting with concrete under a repository condition for radioactive waste. The Uzu tunnel in yamagata prefecture in Japan, constructed during the term of December of 1963 to July 1967, was selected as an appropriate natural analogue: the tunnel wall was made of portland cement and which has been contacting with a bentonite bed during 32 years. Sample analyses indicated that the original bentonite was Na $^{+}$ -type and it changed to Ca $^{2+}$ -type in the range of a few millimeters from the contact. Although a Ca $^{2+}$ leaching was also observed from the concrete near the contact, neither transformation to zeolite nor to illite was recognized. On the other hand, sulfur increased and ettringite (3CaO Al $_{2}$ O $_{3}$ 3CaSO $_{4}$ 4 32H $_{2}$ O) was recognized in the concrete within the depth about 30 mm from the contact.