Department of Geoscience, University of Wisconsin - Madison, Madison, Wisconsin 53706, United States.
Environ Sci Technol. 2012 Jul 3;46(13):7301-9. doi: 10.1021/es2044163. Epub 2012 Jun 18.
Sorption-desorption experiments show that the majority (ca. 80-90%) of U(VI) presorbed to mesoporous and nanoporous alumina could not be released by extended (2 week) extraction with 50 mM NaHCO(3) in contrast with non-nanoporous α alumina. The extent of reduction of U(VI) presorbed to aluminum oxides was semiquantitatively estimated by comparing the percentages of uranium desorbed by anoxic sodium bicarbonate between AH(2)DS-reacted and unreacted control samples. X-ray absorption spectroscopy confirmed that U(VI) presorbed to non-nanoporous alumina was rapidly and completely reduced to nanoparticulate uraninite by AH(2)DS, whereas reduction of U(VI) presorbed to nanoporous alumina was slow and incomplete (<5% reduction after 1 week). The observed nanopore size-dependent redox behavior of U has important implications in developing efficient remediation techniques for the subsurface uranium contamination because the efficiency of in situ bioremediation depends on how effectively and rapidly U(VI) bound to sediment or soil can be converted to an immobile phase.
吸附-解吸实验表明，与非纳米多孔α氧化铝相比，大部分（约 80-90%）预先吸附到中孔和纳米多孔氧化铝上的 U(VI) 不能通过延长（2 周）用 50mM NaHCO(3)进行提取来释放。通过比较缺氧碳酸氢钠从 AH(2)DS 反应和未反应对照样品中解吸的铀百分比，半定量估计了预先吸附到氧化铝上的 U(VI)的还原程度。X 射线吸收光谱证实，AH(2)DS 可迅速且完全地将预先吸附到非纳米多孔氧化铝上的 U(VI)还原为纳米颗粒状的铀矿，而预先吸附到纳米多孔氧化铝上的 U(VI)的还原速度较慢且不完全（1 周后还原率<5%）。在开发用于地下铀污染的有效修复技术方面，观察到的纳米孔尺寸依赖性的 U 氧化还原行为具有重要意义，因为原位生物修复的效率取决于与沉积物或土壤结合的 U(VI)能够多有效地和快速地转化为非活动相。
