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首页> 外文期刊>Environmental Science & Technology >Alteration of Sediments by Hyperalkaline K-Rich Cement Leachate: Implications for Strontium Adsorption and Incorporation
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Alteration of Sediments by Hyperalkaline K-Rich Cement Leachate: Implications for Strontium Adsorption and Incorporation

机译：高碱性富钾水泥渗滤液对沉积物的改变：锶吸附和掺入的意义

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摘要

Results are presented from 1 year batch experiments where K-rich hyperalkaline pH 13.5 young cement water (YCW) was reacted with sediments to investigate the effect of high pH, mineral alteration, and secondary mineral precipitation on ~(90)Sr sorption. After reaction with YCW, Sr sorption was found to be greater than 75% in all samples up to 365 days and 98% in a sample reacted for 365 days at 70 ℃ Scanning electron microscopy analysis of sediment samples reacted at room temperature showed surface alteration and precipitation of a secondary phase, likely a K-rich aluminosilicate gel. The presence of Sr-Si(Al) bond distances in Sr K-edge extended X-ray absorption fine structure (EXAFS) analysis suggested that the Sr was present as an inner-sphere adsorption complex. However, sequential extractions found the majority of this Sr was still exchangeable with Mg~(2+) at pH 7. For the sample reacted for 1 year at 70 ℃, EXAFS analysis revealed clear evidence for ~6 Sr-Si(Al) backscatters at 3.45 A, consistent with Sr incorporation into the neoformed K-chabazite phase that was detected by X- ray diffraction and electron microscopy. Once incorporated into chabazite, ~(90)Sr was not exchangeable with Mg~(2+), and chemical leaching with pH 1.5 HNO_3 was required to remobilize 60% of the ~(90)Sr. These results indicate that, in high pH cementitious leachate, there is significantly enhanced Sr retention in sediments due to changes in the adsorption mechanism and incorporation into secondary silicate minerals. This suggests that Sr retention may be enhanced in this high pH zone and that the incorporation process may lead to irreversible exchange of the contaminant over extended time periods.
机译：结果来自于为期1年的分批实验，其中富含钾的pH 13.5的高碱性年轻水泥水（YCW）与沉积物反应，以研究高pH，矿物变化和二次矿物沉淀对〜（90）Sr吸附的影响。与YCW反应后，在70℃下反应365天，所有样品的Sr吸附均大于75％，在70℃反应365天的样品中Sr的吸附大于98％。室温下反应的沉积物样品的扫描电子显微镜分析显示表面发生了变化。第二相的沉淀，可能是富含钾的硅铝酸盐凝胶。 Sr K边缘扩展X射线吸收精细结构（EXAFS）分析中Sr-Si（Al）键距的存在表明Sr作为内球吸附复合物存在。然而，连续萃取发现该Sr的大部分在pH 7时仍可与Mg〜（2+）交换。对于在70℃反应1年的样品，EXAFS分析显示了〜6 Sr-Si（Al）反向散射的明确证据。在3.45 A的温度下，这与Sr掺入X射线衍射和电子显微镜检测到的新形成的K-菱沸石相一致。一旦掺入菱沸石中，〜（90）Sr就不能与Mg〜（2+）交换，并且需要用pH 1.5 HNO_3进行化学浸出才能使〜（90）Sr的60％迁移。这些结果表明，在高pH值胶结渗滤液中，由于吸附机理的变化和掺入次生硅酸盐矿物中，沉积物中的Sr保留显着增强。这表明在此高pH值区域中Sr的保留可能会增强，并且掺入过程可能导致污染物在延长的时间内发生不可逆的交换。

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  • 来源
    《Environmental Science & Technology》 |2013年第8期|3694-3700|共7页
  • 作者

    Sarah H. Wallace; Samuel Shaw; Katherine Morris; Joe S. Small; Ian T. Burke;

  • 作者单位

    Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom;

    Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom ,Research Centre for Radwaste and Decommissioning and Williamson Research Centre, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, M13 9PL, United Kingdom;

    Research Centre for Radwaste and Decommissioning and Williamson Research Centre, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, M13 9PL, United Kingdom;

    National Nuclear Laboratory, Risley, Warrington, Cheshire, WA3 6AE, United Kingdom;

    Earth Surface Science Institute, School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, United Kingdom;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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