Davis, J A

29 items:

Deep aquifer remediation tools: Theory, design, and performance modeling Categories: Publication; Types: Citation
Evaluation of apatite materials for use in permeable reactive barriers for the remediation of uranium-contaminated groundwater Categories: Publication; Types: Citation
Surface complexation model of uranyl sorption on Georgia kaolinite The adsorption of uranyl on standard Georgia kaolinites (KGa-1 and KGa-1B) was studied as a function of pH (3–10), total U (1 and 10 μmol/l), and mass loading of clay (4 and 40 g/l). The uptake of uranyl in air-equilibrated systems increased with pH and reached a maximum in the near-neutral pH range. At higher pH values, the sorption decreased due to the presence of aqueous uranyl carbonate complexes. One kaolinite sample was examined after the uranyl uptake experiments by transmission electron microscopy (TEM), using energy dispersive X-ray spectroscopy (EDS) to determine the U content. It was found that uranium was preferentially adsorbed by Ti-rich impurity phases (predominantly anatase), which are present in... Categories: Publication; Types: Citation; Tags: Anatase, Kaolinite, Surface complexation, adsorption
Simulation of U(VI) transport in groundwater with variable geochemical conditions Categories: Publication; Types: Citation
Arsenate Adsorption Mechanisms at the Allophane−Water Interface We investigated arsenate (As(V)) reactivity and surface speciation on amorphous aluminosilicate mineral (synthetic allophane) surfaces using batch adsorption experiments, powder X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS). The adsorption isotherm experiments indicated that As(V) uptake increased with increasing [As(V)]o from 50 to 1000 ?M (i.e., Langmuir type adsorption isotherm) and that the total As adsorption slightly decreased with increasing NaCl concentrations from 0.01 to 0.1 M. Arsenate adsorption was initially (0?10 h) rapid followed by a slow continuum uptake, and the adsorption processes reached the steady state after 720 h. X-ray absorption spectroscopic analyses suggest that As(V)... Categories: Publication; Types: Citation

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