Copper binding and release by immobilized transferrin: a new approach to heavy metal removal and recovery

Recently these laboratories have demonstrated that it is possible to use proteins as efficient, selective agents for heavy metal removal and recovery. In this study, transferrin was chemically bound to an insoluble support. The ability of immobilized transferrin to produce clean water was demonstrated. Copper loading was independent of feed concentration. The loaded copper could be readily eluted and concentrated into the gram per liter range. The mechanism of copper release was studied. It was shown that release was dependent on pH and the chelating ability of the stripping agent. Metal release occurred slowly at pH < 7. However, at low pH in the presence of a chelator, metal removal occurred much more efficiently. The binding constant of copper to immobilized transferrin was determined as a function of pH. This information was used to model metal binding and release to the protein/support matrix. (c) 1997 John Wiley & Sons, Inc.