EXAFS Study of Zn and ZnEDTA Sorption at the Goethite (-FeOOH)/Water Interface
نویسندگان
چکیده
EXAFS spectroscopy has been used to compare the sorption mechanism of Zn and ZnEDTA on goethite (a-FeOOH). In the absence of EDTA, Zn is found to form an inner-sphere surface complex. Based on Zn-0 and Zn-Fe distances, Zn is inferred to be located in a distorted oxygen octahedron which shares edges andlor comers with surface Fe octahedra. EXAFS spectra of ZnEDTA in solution and sorbed on goethite are similar, indicating that the ZnEDTA complex does not dissociate following its sorption. The absence of an Fe shell within the first 4 A precludes the existence of Zn-0-Fe bonds and allows us to reject a ligand exchange sorption mechanism involving the formation of Zn-0-Fe linkages.
منابع مشابه
Formation of metal-arsenate precipitates at the goethite-water interface.
Little information is available concerning cosorbing oxyanion and metal contaminants in the environment, yet in most metal-contaminated areas, cocontamination by arsenate [AsO4, As(V)] is common. This study investigated the cosorption of As(V) and Zn on goethite at pH 4 and 7 as a function of final solution concentration. Complimentary extended X-ray absorption fine structure (EXAFS) spectrosco...
متن کاملEffect of iron oxide coatings on zinc sorption mechanisms at the clay-mineral/water interface.
Oxide surface coatings are ubiquitous in the environment, but their effect on the intrinsic metal uptake mechanism by the underlying mineral surface is poorly understood. In this study, the zinc (Zn) sorption complexes formed at the kaolinite, goethite, and goethite-coated kaolinite surfaces, were systematically studied as a function of pH, aging time, surface loading, and the extent of goethit...
متن کاملEXAFS study of mercury(II) sorption to Fe- and Al-(hydr)oxides. II. Effects of chloride and sulfate.
Common complexing ligands such as chloride and sulfate can significantly impact the sorption of Hg(II) to particle surfaces in aqueous environmental systems. To examine the effects of these ligands on Hg(II) sorption to mineral sorbents, macroscopic Hg(II) uptake measurements were conducted at pH 6 and [Hg](i)=0.5 mM on goethite (alpha-FeOOH), gamma-alumina (gamma-Al(2)O(3)), and bayerite (beta...
متن کاملX-Ray Absorption Spectroscopy of Strontium(II) Coordination.
Sorption of dissolved strontium on kaolinite, amorphous silica, and goethite was studied as a function of pH, aqueous strontium concentration, the presence or absence of atmospheric CO(2) or dissolved phosphate, and aging over a 57-day period. Selected sorption samples ([Sr(aq)](i) approximately 0.5-1x10(-3) m) were examined with synchrotron X-ray absorption spectroscopy (XAS) at low (13-23 K) ...
متن کاملKinetic analysis of the bacterial reduction of goethite.
The kinetics of dissimilatory reduction of goethite (alpha-FeOOH) was studied in batch cultures of a groundwater bacterium, Shewanella putrefaciens, strain CN32 in pH 7 bicarbonate buffer. The rate and extent of goethite reduction were measured as a function of electron acceptor (goethite) and donor (lactate) concentrations. Increasing goethite concentrations increased both the rate and extent ...
متن کامل