کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4483987 | 1316905 | 2009 | 9 صفحه PDF | دانلود رایگان |
Removal of selenium oxyanions by the binary oxide systems, Al- or Fe-oxides mixed with X-ray noncrystalline SiO2, was previously not well understood. This study evaluates the adsorption capacity and kinetics of selenium oxyanions by different metal hydroxides onto SiO2, and uses X-ray absorption spectroscopy (XAS) to assess the interaction between selenium oxyanions and the sorbents at pH 5.0. The binary oxide systems of Al(III)- or Fe(III)-oxides mixed with SiO2 were prepared, and were characterized for their surface area, point of zero charge (PZC), pH envelopes, X-ray diffraction analysis (XRD), and then macro-scale adsorption isotherm and kinetics of selenite and selenate, micro-scale adsorption XAS. The adsorption capacity of selenite and selenate on Al(III)/SiO2 is greater than on Fe(III)/SiO2. Adsorption isothermal and kinetic data of selenium can be well fitted to the Langmuir isotherm and pseudo-second-order kinetic models. Based on simple geometrical constraints, selenite on both the binary oxide systems forms bidentate inner-sphere surface complexes, and selenate on Fe(III)/SiO2 forms stronger complexes than on Al(III)/SiO2.
Journal: Water Research - Volume 43, Issue 17, September 2009, Pages 4412–4420