In this study, a new mathematical model was suggested to account for the effect of internal and external diffusion on fluid–solid
noncatalytic reactions. The special features of this model are the combination of the transport processes and the chemical
reaction kinetics with the added factor due to the structural properties of the solid reactant. The model was examined theoretically
and experimentally. A reactive cloth filter that separates radionuclides from radioactive waste solutions is used as a practical
application for the model. Analyses of the respective rate data in accordance with another two theoretical models showed that
process is controlled by the rate of the diffusion step. The external and internal mass transfer constants across the liquid
film and the resin matrix were determined from the graphical representation of the proposed model. The practical validation
with the theoretical results offered satisfactory agreement at most of the process stages.