thus the membrane ligand combination readily removed iron copper and nickel from the source solution and these three metals could be separated from the source solution and recovered a 0 2 g sheet of the membrane of example 11 was placed in a beaker containing 25 ml of 5 ppm potassium in deionized distilled water at ph 8 the membrane was contacted with this source solution for 120 minutes the membrane was then removed from the source solution rinsed in water and placed in 5 ml of a receiving solution consisting of 0 1m hcl the source and receiving solutions were analyzed before and after contact with the membrane for potassium using flame aa spectroscopy initially the source solution contained 15 ppm potassium but after contact with the membrane it contained lt 1 ppm of potassium the receiving solution contained potassium at a level below the level of detection but after contact with the membrane contained 75 ppm potassium thus potassium could be readily removed from the source solution by binding to the membrane and recovered by elution in a receiving solution a 0 2 g sheet of the membrane of example 12 was placed in a beaker containing 25 ml of 5 ppm of each of lead cadmium mercury copper and nickel in tap water the membrane was contacted with this source solution for 480 minutes the membrane was then removed from the source solution rinsed with water and placed in 5 ml of a receiving solution consisting of 6m hcl the source and receiving solutions were analyzed before and after contact with the membrane for mercury cadmium and nickel using icp spectroscopy and for lead copper and mercury using flame aa spectroscopy initially the source solution contained 5 ppm of each of lead cadmium mercury copper.