PAN/PVDF chelating membrane for simultaneous removal of heavy metal and organic pollutants from mimic industrial wastewater

The polyacrylonitrile/polyvinylidene fluoride (PAN/PVDF) chelating membrane with amidoxime groups was prepared to simultaneously remove metallic and organic pollutants from mimic industrial wastewater. The main purpose of this study is to investigate the interaction between metal ions and protein molecules, and synergistic effects on the pollutant removal efficiency through the chelating membrane. Lysozyme and bovine serum albumin (BSA) were used as organic pollutants and Cu2+, Pb2+ and Cd2+ were used as metal components in this study. As one of the metal ions (Cu2+, Pb2+ or Cd2+) and one of the proteins (lysozyme or BSA) are present in the solution, the metal removal rate is improved due to the interaction of metal ions with protein, to form a metal-protein complex. At the same time, the lysozyme rejection efficiency decreases, but the BSA rejection efficiency increases. For the mixture consisting of one metal ion and two proteins, the metal removal rate is higher than that for the case (one metal ion + lysozyme), but lower than that for the case (one metal ion + BSA). Meanwhile, the protein retention efficiency decreases, since the interaction between lysozyme and BSA disturbs the retention efficiency of each protein. As three metal ions and two proteins are present in the solution, the ion removal efficiency is significantly improved, and the protein retention efficiency is increased as well, which is due to the fact that there are much more chances for forming metal-protein complexes.