Abstract
The adsorption of tungsten from aqueous solutions of ammonium metatungstate on to alumina has been studied, an adsorption isotherm at 20°C being obtained. The isotherm had a sigmoidal shape and reached a flat plateau region at an adsorbed concentration of 100 mg W/g Al2O3 within the range of initial concentrations used (up to 70,000 ppm W). A proposed relationship between the adsorbed concentration and the equilibrium solution concentration has enabled the adsorption equilibrium parameters to be estimated.
Impregnation of flat thin layers of alumina with concentrated tungstate solutions (5,100, 31,200 and 72,800 ppm W) has also been studied. Fits between the experimental tungsten concentration profiles and those obtained via a theoretical model of the impregnation phenomena allowed the adsorption kinetic parameters to be obtained. These parameters are useful in predicting the concentration profiles resulting from the pore-filling impregnation of pellets provided a suitable theoretical model is employed.
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