The conditional rates of permeation Cs-137 from nitrate solution was investigated with emulsion liquid membranes (ELMs), crown ether (18C6) in xylene in double emulsions by SPAN 80/85 surfactant and ephedrine as stripping phase. The analysis of pertraction rates based on the ionization constants of ephedrine hydrochloride (EPH) and different pHs is proposed and tested on a new model. The consistency of the results supports the validity of the approach and confirms the diffusion limiting mechanism for the pertraction of Cs (137) in this system contains EPH in the stripping phase.