Srour Rafif K, Mcdonald Louis M
Division of Plant & Soil Sciences, West Virginia University, Morgantown, West Virginia 26506-6108, USA.
Environ Sci Technol. 2005 Sep 15;39(18):7111-7. doi: 10.1021/es0501161.
The effects of ethanol- and methanol-water mixtures on Zn and Cd sorption onto bentonite and illite were investigated at low initial metal concentration (< or =10(-5) M) and low ionic strength (2.5 mM Ca(NO3)2). For all cosolvent fractions, the percent coverage of Zn and Cd to clay minerals was low (<5%) and independent of the solution dielectric constant, epsilon, except for Zn at 10 microM. Cadmium sorption to bentonite and illite was independent of epsilon. Zinc sorption varied significantly between clay types, cosolvent type, and cosolvent fraction. The partitioning of Zn to bentonite increased from 0 to 10% alcohol-water fraction and decreased after 10%. The same pattern was observed for the partitioning of Zn on illite in methanol-water mixtures. In ethanol-water mixtures, Kf for Zn on illite increased continuouslyfrom 0 to 50% ethanol. The decreased partitioning and hence mobility of Zn to bentonite and illite after 10% alcohol (only in methanol-water mixtures for illite) suggests a potential environmental threat resulting from increased transport of this metal in subsurface environments where these cosolvents are present.
在低初始金属浓度（≤10⁻⁵ M）和低离子强度（2.5 mM Ca(NO₃)₂）条件下，研究了乙醇 - 水和甲醇 - 水混合物对膨润土和伊利石吸附锌和镉的影响。对于所有共溶剂比例，锌和镉在粘土矿物上的覆盖百分比很低（<5%），且与溶液介电常数ε无关，但10 μM的锌除外。镉在膨润土和伊利石上的吸附与ε无关。锌在不同粘土类型、共溶剂类型和共溶剂比例之间的吸附差异显著。锌在膨润土上的分配比例从0至10%醇 - 水比例时增加，在10%之后降低。在甲醇 - 水混合物中，锌在伊利石上的分配也观察到相同模式。在乙醇 - 水混合物中，锌在伊利石上的分配系数Kf从0至50%乙醇持续增加。10%醇之后（仅在甲醇 - 水混合物中伊利石的情况）锌在膨润土和伊利石上的分配比例降低以及迁移率降低，这表明在存在这些共溶剂的地下环境中，这种金属迁移增加会带来潜在的环境威胁。
