Surface functionalization of PTFE membranes with hyperbranched poly(amidoamine) for the removal of Cu2+ ions from aqueous solution

We describe here the preparation of hyperbranched poly(amidoamine)-grafted poly(tetrafluoroethylene) microfiltration membranes, and demonstrate their potential applicability to water treatment and heavy metals removal. The membranes were fabricated by surface amination of PTFE membranes with hydrazine, followed by chemical coupling with the hydrophilic chelating agent hyperbranched poly(amidoamine) (HPAMAM). Membrane structures were evaluated by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and contact angle measurements. The amount of grafted HPAMAM was quantitated by the acid dye adsorption/desorption method. Coupling of HPAMAM to PTFE membranes greatly enhanced water flux without negatively affecting their rejection property as well as increasing its ability to remove heavy metal ions. At an operating pressure of 25 kPa, the pure water flux of PTFE membrane was nearly 0 L/m2 h, whereas the flux of HPAMAM-grafted PTFE membranes was 635±9 L/m2 h. In addition, HPAMAM-grafted PTFE membranes adsorbed 1.42 g/m2 Cu2+ ions from aqueous solution, with up to 90% desorption under acidic conditions and highly preserved adsorption capacity for Cu2+ ions with re-using cycles. These results indicate HPAMAM-grafted PTFE microfiltration membranes can be highly efficient and reusable for the removal of toxic heavy metal ions and these microfiltration membranes can be useful in water treatment technology.