In this study, we investigate the effect of speciation on tungstate sorption, which is one of the dominant mechanisms controlling metal mobility. Batch uptake experiments showed Langmuir-type isotherms. The pH dependence of uptake shows that sorption decreases with increasing pH. While W sorbed on boehmite at pH4 showed almost irreversible behaviors, those of pH 8 samples were more reversible. These desorption experiments could imply surface precipitation or precipitation occurs on boehmite surface at pH 4, and adsorption mechanism is dominant at pH 8. Our characterization of sorption products used X-ray absorption spectroscopy(XAS) and differential PDF, and we also investigated the use of Raman spectroscopy. 5 uM and 1000 uM at pH4 and pH 8 were selected to represent monomeric and polymeric W structures on the boehmite surface. With W desorption experiments on boehmite, differential PDF and XAS  results could support W cluster on boehmite surface.

Sorption mechanisms of tungsten in water-metal oxyhydroxide interface

243rd National Meeting (2012)

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