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Kaneta, Yui; Kobayashi, Toru; Tsuji, Takuya; Honda, Mitsunori; Yokoyama, Keiichi; Mampuku, Yuzo*; Yaita, Tsuyoshi*
Clays and Clay Minerals, 73, p.e26_1 - e26_8, 2025/04
Times Cited Count：1 Percentile：0.00(Chemistry, Physical)The desorption behavior of stable Cs adsorbed onto weathered biotite (WB), a clay mineral abundant in Fukushima soils, was investigated using a mechanochemical (MC) method that combines physical grinding by ball impact with a wet process promoting chemical reactions. The results, oxalic acid desorbed Cs to some extent without significantly affecting the layered structure of the clay minerals; ammonium chloride, showed an exfoliation of the layer structure, resulting in a stable desorption of Cs independent of samples. Regarding the real soil samples collected in Fukushima, the MC method using ammonium chloride solution desorbed 80% of 
Cs. In contrast, oxalic acid did not always result in radioactive Cs made sufficiently desorbed for all the samples. Based on these findings, the MC method with ammonium chloride effectively promotes radioactive Cs desorption from interlayers due to synergistic effects from the layered structure's exfoliation and chemical interaction.
Yuguchi, Takashi; Sasao, Eiji; Ishibashi, Masayuki; Nishiyama, Tadao*
American Mineralogist, 100(5-6), p.1134 - 1152, 2015/05
Times Cited Count：43 Percentile：76.59(Geochemistry & Geophysics)This paper describes the biotite chloritization process with a focus on mass transfer in the Toki granitic pluton, Central Japan, and also depicts the temporal variations in chemical characteristics of hydrothermal fluid associated with chloritization during the sub-solidus cooling of the pluton. Singular value decomposition (SVD) analysis results in chloritization reaction equations for eight mineral assemblages, leading to the quantitative assessment of mass transfer between the reactant and product minerals, and inflow and outflow of components through the hydrothermal fluid. The matrices for SVD analysis consist of arbitrary combinations of molar volume and closure component in the reactant and product minerals. The eight reactions represent the temporal variations of chemical characteristics of the hydrothermal fluid associated with chloritization: the progress of chloritization results in gradual increase of silicon, potassium and chlorine and gradual decrease of calcium and sodium in the hydrothermal fluid with temperature decrease. The biotite chloritization involves two essential formation processes: Formation Process 1, small volume decrease from biotite to chlorite and large inflow of metallic ions from the hydrothermal fluid, and Formation Process 2, large volume decrease and large outflow of metallic ions into hydrothermal fluid. Chlorite produced during Formation Process 1 dominates over that of Formation Process 2, resulting in the gradual decrease of metallic components in the hydrothermal fluid with chloritization progress. The combination of continuous reactions based on compositional variations in chlorite together with corresponding continuous Al
variations gives an indication of the temporal variations in rates of decreasing and increasing concentration of chemical components in the hydrothermal fluid associated with chloritization.
Yuguchi, Takashi; Sasao, Eiji; Ishibashi, Masayuki; Nishiyama, Tadao*
no journal, ,
no abstracts in English
Yomogida, Takumi; Higashi, Kotaro*; Kawamura, Naomi*; Kitatsuji, Yoshihiro; Takahashi, Yoshio*
no journal, ,
Biotite, a layered silicate mineral, is known to be a host phase for uranium(U) in U mines. There are still many unclear factors regarding its U accumulation mechanism. In this study, U adsorption experiment was conducted on artificially weathered biotite by removing interlayer potassium. The results showed that the ratio of reduced species of U increased with increasing the K loss ratio in interlayer, indicating that U reduction occurred at cleavages developed by weathering of the biotite.
Fukatsu, Yuta; Hu, Q.*; Tachi, Yukio
no journal, ,
