GENERALIZED SOLUTION OF THE TRANSIENT BACKFLOW MODEL-EQUATIONS FOR TRACER CONCENTRATION IN STAGEWISE LIQUID EXTRACTION COLUMNS

A generalized solution is presented of transient backflow model equati ons, for use in determining the backmixing ratio for stagewise extract ion columns from pulse tracer injection data obtained over a wide rang e of operating conditions. Results obtained with this model agreed wit h those given by earlier solutions for restricted boundary conditions. The generalized solution was also used successfully to predict the tr acer response for a Kuhni column in which a tracer pulse was injected into the end stage and samples were withdrawn from two downstream stag es. It was observed that numerical instability can occur in all soluti ons at short response times for low values of the backflow ratio, alph a, and a relatively large number of stages.