THE DIAFILTRATION METHOD FOR THE STUDY OF THE BINDING OF MACROMOLECULES TO HEAVY-METALS

A membrane process known as continuous diafiltration has been utilized as an effective method for the study of the binding of macromolecules to ions. Data from one experiment will result in an entire isotherm w hen temperature and pH are closely controlled. This paper discusses th e theory of continuous diafiltration and describes a procedure for qua ntifying variable membrane rejection behavior. The binding of five hea vy metals (Cd, Cu, Ni, Pb, and Zn) individually and collectively, to n atural lecithin was studied. Copper exhibited stronger binding when it was the lone ion compared to when it was in a mixture of the five met als. Further, the membrane rejected copper at a constant rate of 10% i n the first case compared to a variable rate with an average of 79% in the second. This work was performed to characterize the binding of le cithin to heavy metals as a step in the development of a treatment tec hnique ter-med micellar enhanced ultrafiltration.