State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
J Hazard Mater. 2011 Feb 15;186(1):842-8. doi: 10.1016/j.jhazmat.2010.11.076. Epub 2010 Nov 25.
Co-adsorption of norfloxacin (Nor) and Cu(II) on montmorillonite at pH 4.5, 7.0 and 9.0 was studied by integrated batch adsorption experiments and extended X-ray absorption fine structure (EXAFS) spectroscopy. Under such pH conditions the dominant species of Nor are cation (Nor(+)), zwitterion (Nor(±)), and anion (Nor(-)), respectively. Results indicated that Nor sorption decreased with an increase of solution pH. The presence of Cu(II) slightly suppressed the Nor(+) sorption at pH 4.5, while increased Nor(±) and Nor(-)sorption on montmorillonite at pH 7.0 and 9.0, respectively. In contrast, Nor increased Cu(II) adsorption at pH 4.5, but had little effect on the adsorption of Cu(II) on montmorillonite at pH 7.0 and 9.0. Spectroscopic results showed that, at pH 4.5, Nor(+) was sorbed on montmorillonite by the formation of outer-sphere montmorillonite-Nor-Cu(II) ternary surface complex. At pH 7.0, montmorillonite-Nor-Cu(II) and montmorillonite-Cu(II)-Nor ternary surface complexes co-exist. At pH 9.0, montmorillonite-Cu(II)-Nor ternary surface complex was likely formed, which was different to Cu(II)(Nor)(2) precipitate of the solution.
在 pH 值为 4.5、7.0 和 9.0 条件下，通过整合批吸附实验和扩展 X 射线吸收精细结构（EXAFS）光谱法研究了诺氟沙星（Nor）和 Cu(II)在蒙脱石上的共吸附作用。在这些 pH 条件下，Nor 的主要存在形式分别为阳离子（Nor(+)）、内盐（Nor(±)）和阴离子（Nor(-)）。结果表明，Nor 的吸附随着溶液 pH 值的增加而降低。Cu(II)的存在略微抑制了在 pH 4.5 时 Nor(+)的吸附，而在 pH 7.0 和 9.0 时分别增加了 Nor(±)和 Nor(-)在蒙脱石上的吸附。相反，Nor 增加了 Cu(II)在 pH 4.5 时的吸附，但对 pH 7.0 和 9.0 时 Cu(II)在蒙脱石上的吸附影响不大。光谱结果表明，在 pH 4.5 时，Nor(+)通过形成外配位蒙脱石-Nor-Cu(II)三元表面配合物而被蒙脱石吸附。在 pH 7.0 时，共存蒙脱石-Nor-Cu(II)和蒙脱石-Cu(II)-Nor 三元表面配合物。在 pH 9.0 时，可能形成了蒙脱石-Cu(II)-Nor 三元表面配合物，这与溶液中的 Cu(II)(Nor)(2)沉淀不同。
