| Project/Area Number |
14350259
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Geotechnical engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
WADA Shin-ichiro Kyushu Uniy, Faculty of Agriculture, Associate Professor, 大学院・農学研究院, 助教授 (60108678)
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| Co-Investigator(Kenkyū-buntansha) |
SAEKI Kazutoshi Kyushu Universiy, Biotron Institute, Associate Professor, 生物環境調節センター, 助教授 (30284780)
NAKAGAWA Kei Kagoshima University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (90315135)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥12,200,000 (Direct Cost: ¥12,200,000)
Fiscal Year 2004: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2003: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2002: ¥7,600,000 (Direct Cost: ¥7,600,000)
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| Keywords | Soil pollution / Heavy metal / Stabilization / Elution / Bioavailability / 粘土鉱物 / 層状ケイ酸塩 / 酸化物鉱物 |
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| Research Abstract |
The objective of the study is to control the solubility of harmful elements in polluted soils by incorporating them into newly formed minerals that are synthesized in situ by mixing the soil with silica and magnesia. In an first attempt, the mixturesof silica and magnesia were reacted with solutions of fluoride The tow oxide reacted promptly to yield poorly ordered trioctahedral layer silicate minerals. The presence of fluoride ion accelerated the mineral formation and accordingly a part of fluoride was stabilized. However, the reaction was not fast enough to suppress the solubility below the soil environmental standard by this process alone.
As an attempt at fixing nickel and copper ions in octahedral layer of tri-octahedral layer silicate minerals, solutions containing these cations were mixed with mixture of noncrystalline silica and magnesia. Powder X-ray diffraction and FT-IR studies of the reaction products indicated that poorly developed layer silicates formed in 30 days after mi
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xing and at least a part of the heavy metal cations were incorporated in octahedral layers. At a solid : sokution ratio of 2 L/kg the initial copper and nickel concentration of 8000 mg/L dropped to <0.01 mg/L. By an addition of the silica-magnesia mixture at 100 g/kg to artificially contaminated soils containing several thousand mg/kg of copper and nickel also dramatically reduced the solubility of these metals and the concentrations of these metals in 1:10 water extract were <0.01 mg/L. Since the addition of magnesia raises solution pH, the enhanced surface complexation is another mechanism of the observed stabilization effect.
The rate of layer silicate formation at normal temperatures was slower than that we expected at the planning stage of this study and the monitoring is still on-going. The results obtained thus far suggest that the incorporation of silica-magnesia mixture into contaminated soil will be a promising stabilization technology in landfill site that accept heavily contaminated soils since surface Less
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