Gold is a highly valuable metal that can concentrate in iron-rich exogenetic horizons such as laterites. An improved knowledge of the retention mechanisms of gold onto highly reactive soil components such as iron oxyhydroxides is therefore needed to better understand and predict the geochemical behavior of this element. In this study, we use EXAFS information and titration experiments to provid...

The behavior of adsorbed species on metal (hydr)oxides under water unsaturated conditions has been seldom studied despite its major implications in several domains such as geochemistry and heterogeneous catalysis. In this study, chemical forms phthalate iron hydroxide (goethite) were investigated by infrared spectroscopy upon hydration dehydration goethite particle aggregates. Experimental resu...

Extracellular polymeric substances (EPS) constitute a heterogeneous mixture of polyelectrolytes that mediate biomineralization and bacterial adhesion and stabilize biofilm matrixes in natural and artificial environments. Although nucleic acids are exuded extracellularly and are purported to be required for biofilm formation, direct evidence of the active mechanism is lacking. EPS were extracted...

-Mixtures of synthetic Al-substituted goethite (a-Feo.814AloA86OOH) and hematite (a-Fel.658Alo.34203) (75, 50, 25, 3~ hematite by weight) were studied by M6ssbauer spectroscopy to evaluate the use of that technique for quantitative analysis. M6ssbauer spectra for these mixtures, obtained in the temperature range 12-130 K, were better fitted by a distribution of magnetic fields than by two magne...

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 goethi...

Analytical isotherm equations such as Langmuir and Freundlich isotherms are widely used for modeling adsorption data. However, these isotherms are primarily useful for simulating data collected at a fixed pH value and cannot be easily adapted to simulate pH-dependent adsorption effects. Therefore, most adsorption studies currently use numerical surface-complexation models (SCMs), which are more...