LIQUID PHASE MASS TRANSFER IN ION EXCHANGE BASED ON THE HYDRAULIC RADIUS MODEL

Abstract

Applying the hydraulic-radius model to the flow in a packed bed, ion exchange liquidphase mass transfer is analysed and liquid-phase effective diffusivity, De'', based on the model is compared with the diffusivity, De, based on the film model. The maximum difference between these values was about 5% for the range of diffusivity ratio a>1 and 16% for a<1. Therefore, even if the value of De is used as an approximation, no significant error will appear. Furthermore, experimental results were correlated by the use of individual diffusivity for isotopic ion exchange and De'' for mutual ion exchange. These data satisfy the equation
J^*'' ={(1-ε)/ε}1/3 k^*Sc^2/3£/us=1.85Re''^-2/3, when Re''<100.