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Tanaka K, Yamaji K, Masuya H, Tomita J, Ozawa M, Yamasaki S, Tokunaga K, Fukuyama K, Ohara Y, Maamoun I, Yamaguchi A, Takahashi Y, Kozai N, Grambow B. Microbially formed Mn(IV) oxide as a novel adsorbent for removal of Radium. CHEMOSPHERE 2024; 355:141837. [PMID: 38554863 DOI: 10.1016/j.chemosphere.2024.141837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2023] [Revised: 03/13/2024] [Accepted: 03/27/2024] [Indexed: 04/02/2024]
Abstract
Radioactivity of Ra isotopes in natural waters is of serious concern. Control of 226Ra concentrations in tailings ponds, which store waste from U ore extraction processes, is an important issue in mill tailings management. In this study, we tested microbially formed Mn(IV) oxide as an adsorbent for removal of Ra in water treatment. Biogenic Mn(IV) oxide (BMO) was prepared using a Mn(II)-oxidizing fungus, Coprinopsis urticicola strain Mn-2. First, adsorption experiments of Sr and Ba, as surrogates for Ra, onto BMO were conducted in aqueous NaCl solution at pH 7. Distribution coefficients for Ba and Sr were estimated to be ∼106.5 and ∼104.3 mL/g, respectively. EXAFS analysis indicated that both Sr and Ba adsorbed in inner-sphere complexes on BMO, suggesting that Ra would adsorb in a similar way. From these findings, we expected that BMO would work effectively in removal of Ra from water. Then, BMO was applied to remove Ra from mine water collected from a U mill tailings pond. Just 7.6 mg of BMO removed >98% of the 226Ra from 3 L of mine water, corresponding to a distribution coefficient of 107.4 mL/g for Ra at pH ∼7. The obtained value was convincingly high for practical application of BMO in water treatment. At the same time, the high distribution coefficient indicates that Mn(IV) oxide can be an important carrier and host phase of Ra in the environment.
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Affiliation(s)
- Kazuya Tanaka
- Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan; Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, Kagamino, Tomata, Okayama, 708-0698, Japan.
| | - Keiko Yamaji
- Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan
| | - Hayato Masuya
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Jumpei Tomita
- Department of Radiation Protection, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Mayumi Ozawa
- Department of Radiation Protection, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Shinya Yamasaki
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8577, Japan
| | - Kohei Tokunaga
- Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, Kagamino, Tomata, Okayama, 708-0698, Japan
| | - Kenjin Fukuyama
- Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, Kagamino, Tomata, Okayama, 708-0698, Japan
| | - Yoshiyuki Ohara
- Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, Kagamino, Tomata, Okayama, 708-0698, Japan
| | - Ibrahim Maamoun
- Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Akiko Yamaguchi
- Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan; Center for Computational Science and e-Systems, Japan Atomic Energy Agency, 178-4 Wakashiba, Kashiwa, Chiba, 277-0871, Japan; Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yoshio Takahashi
- Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Naofumi Kozai
- Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan; Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency, Kagamino, Tomata, Okayama, 708-0698, Japan
| | - Bernd Grambow
- Advanced Science Research Center, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan; Subatech, UMR 6457 IMT-Atlantique, Université de Nantes CNRS/IN2P3, Nantes, France
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Simultaneous Sequestration of Co2+ and Mn2+ by Fungal Manganese Oxide through Asbolane Formation. MINERALS 2022. [DOI: 10.3390/min12030358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Biogenic manganese oxides (BMOs) have attractive environmental applications owing to their metal sequestration and oxidizing abilities. Although Co readily accumulates into Mn oxide phases in natural environments, the Co2+ sequestration process that accompanies the enzymatic Mn(II) oxidation of exogenous Mn2+ remains unknown. Therefore, we prepared newly formed BMOs in a liquid culture of Acremonium strictum KR21-2 and conducted repeated sequestration experiments in a Mn2+/Co2+ binary solution at pH 7.0. The sequestration of Co2+ by newly formed BMOs (~1 mM Mn) readily progressed in parallel with the oxidation of exogenous Mn2+, with higher efficiencies than that in single Co2+ solutions when the initial Co2+ concentrations (0.16–0.8 mM) were comparable to or lower than the exogenous Mn2+ concentration (~0.8 mM). This demonstrates a synergetic effect on Co sequestration. Powder X-ray diffraction showed a typical pattern for asbolane only when newly formed BMOs were treated in Mn2+/Co2+ binary systems, implying that the enzymatic Mn(II) oxidation by newly formed BMOs favored asbolane formation. Cobalt K-edge X-ray absorption near-edge structure measurements showed that both Co(II) and Co(III) participated in the formation of the asbolane phase in the binary solutions, whereas most of the primary Co2+ was sequestered as Co(III) in the single Co2+ solutions, which partly explains the synergetic effects on Co sequestration efficiency in the binary solutions. The results presented here provide new insights into the mechanism of Co interaction with Mn oxide phases through asbolane formation by enzymatic Mn(II) oxidation under circumneutral pH conditions.
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