Ostergren John D., Brown Gordon E., Parks George A., Persson Per
Surface and Aqueous Geochemistry Group, Department of Geological and Environmental Sciences, Stanford University, Stanford, California, 94305-2115
J Colloid Interface Sci. 2000 May 15;225(2):483-493. doi: 10.1006/jcis.1999.6702.
The effects of sulfate anions on the uptake of Pb(II) onto goethite were investigated at the molecular level using in situ Pb L(III)-EXAFS and ATR-FTIR spectroscopies. Macroscopic uptake data show that Pb uptake can be enhanced by at least 30% at pH 5 in the presence of 3.16 mM sulfate and that sulfate uptake at pH 7 can be enhanced by more than a factor of 3 in the presence of 1.0 mM Pb. Consistent with behavior in sulfate-free systems, Pb(II) forms inner-sphere complexes sharing either corners or edges with Fe(O,OH)(6) octahedra under all conditions studied. The relative fraction of corner-sharing complexes is, however, significantly enhanced in the presence of sulfate at pH 5, 6, and 7 (all conditions studied) and additional sulfate species with C(3v) or lower point symmetry were noted in the presence of Pb by ATR-FTIR. Drawing on bond valence and structural constraints developed in J. D. Ostergren et al. (2000, J. Colloid Interface Science 224, 000-000), these results indicate formation of Type A ternary complexes bonded to the surface through Pb that is bound as a bridging bidenate complex to two adjacent A-type (singly coordinated) surface oxygens (( identical withFe-O)(2)-Pb-OSO(3)). Copyright 2000 Academic Press.
利用原位铅L(III)-扩展X射线吸收精细结构光谱（EXAFS）和衰减全反射傅里叶变换红外光谱（ATR-FTIR），在分子水平上研究了硫酸根阴离子对针铁矿吸附Pb(II)的影响。宏观吸附数据表明，在pH为5且存在3.16 mM硫酸根的情况下，Pb的吸附量可提高至少30%；在pH为7且存在1.0 mM Pb的情况下，硫酸根的吸附量可提高3倍以上。与无硫酸根体系中的行为一致，在所研究的所有条件下，Pb(II)均形成与Fe(O,OH)(6)八面体共享角或边的内球络合物。然而，在pH为5、6和7（所有研究条件）时，存在硫酸根的情况下，共享角络合物的相对比例显著提高，并且通过ATR-FTIR发现在存在Pb的情况下有具有C(3v)或更低点群对称性的额外硫酸根物种。借鉴J. D. Ostergren等人（2000年，《胶体与界面科学杂志》224, 000 -
