Abstract
The influence of reversible adsorption and diffusion of molybdenum during the drying step on the redistribution of molybdenum which had been previously impregnated on alumina spheres is presented.
Two approximate theoretical models are postulated to interpret this phenomenon. The first assumes that redistribution is due solely to the diffusion of molybdenum in the solution within the pores towards the centre of the pellet, while the other is based on the assumption that solvent evaporation also has an influence on the process, since this leads to a consequent increase of solute in the interior of the pores.
In both models it is assumed that equilibrium between adsorbed molybdenum and that in the solution, as a consequence of reversible adsorption, occurs simultaneously with molybdenum diffusion.
A good fit between the theoretical profiles and the experimental points was observed in all samples dried slowly at room temperature and humidity.
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