Selective separation of copper and molybdenum with liquid surfactant membranes which contain 2 -ethylhexyl-mono-2-ethylhexyl phosphonic acid (PC-88 A) as a carrier and L-glutamic acid dioleyl ester ribitol as a surfactant, was conducted in a Mixco extractor. The concentration profile of molybdenum along the column was measured. The experimental results are analyzed by the backflow model taking into account the interfacial reaction between molybdenum in the continuous aqueous phase and the carrier in the liquid membrane phase. The concentration profile for molybdenum in a dual-component solution along the column is successively simulated without using a special fitting parameter just by the interfacial reaction rate constant obtained in a previous batch-wise experiment.