• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Environmental Science & Technology >Transformation of Two-line Fenihydrite to Goethite and Hematite as a Function of pH and Temperature
【24h】

Transformation of Two-line Fenihydrite to Goethite and Hematite as a Function of pH and Temperature

机译：pH和温度的函数影响两线铁水长石向针铁矿和赤铁矿的转化

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Under oxic aqueous conditions, two-line ferrihydrite gradually transforms to more thermodynamically stable and more crystalline phases, such as goethite and hematite. This temperature- and pH-dependent transformation can play an important role in the sequestration of metals and metalloids adsorbed onto ferrihydrite. A comprehensive assessment of the crystallization of two-line ferrihydrite with respect to temperature (25, 50, 75, and 100 °C) and pH (2,7, and 10) as a function of reaction time (minutes to months) was conducted via batch experiments. Pure and transformed phases were characterized by X-ray diffraction (XRD), X-ray absorption near-edge spectroscopy (XANES), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The rate of transformation of two-line ferrihydrite to hematite increased with increasing temperature at all pHs studied and followed first-order reaction kinetics. XRD and XANES showed simultaneous formation of goethite and hematite at 50 and 75 °C at pH 10, with hematite being the dominant product at all pHs and temperatures. With extended reaction time, hematite increased while goethite decreased, and goethite reaches a minimum after 7 days. Observations suggest two-line ferrihydrite transforms to hematite via a two-stage crystallization process, with goethite being intermediary. The findings of this study can be used to estimate rates of crystallization of pure two-line ferrihydrite over the broad range of temperatures and pH found in nature.
机译：在含氧水溶液条件下，两线水铁矿逐渐转变为热力学更稳定且更结晶的相，例如针铁矿和赤铁矿。这种依赖于温度和pH的转化可以在螯合吸附到三水铝石上的金属和准金属中起重要作用。根据反应时间（数分钟至数月），对两线水铁矿的结晶温度，温度（25、50、75和100°C）和pH（2,7和10）进行了综合评估。通过批量实验。通过X射线衍射（XRD），X射线吸收近边缘光谱（XANES），原子力显微镜（AFM）和扫描电子显微镜（SEM）对纯相和转化相进行表征。在所有研究的pH值下，随着温度的升高，两线亚铁水合物转变为赤铁矿的速率增加，并且遵循一级反应动力学。 XRD和XANES显示在50和75°C，pH 10时同时形成针铁矿和赤铁矿，其中赤铁矿是在所有pH和温度下的主要产物。随着反应时间的延长，赤铁矿增加而针铁矿减少，针铁矿在7天后达到最小值。观察表明，两线铁水合物通过两步结晶过程转变为赤铁矿，其中针铁矿为中间物。这项研究的结果可用于估算自然界中存在的宽温度和pH范围内的纯两线三水铁矿的结晶速率。

著录项

  • 来源
    《Environmental Science & Technology》 |2011年第1期|p.268-275|共8页
  • 作者

    SOUMYA DAS; M. JIM HENDRY; JOSEPH ESSILFIE-DUGHAN;

  • 作者单位

    Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada;

    Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada;

    Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada;

  • 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);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号