A novel potential-responsive ion exchange film system for heavy metal removal

In this study, we report on a novel potential-responsive hybrid film system for heavy metal removal, which was composed of a layered α-zirconium phosphate (α-ZrP) nanosheet and a conducting polyaniline (PANI)-intercalated chain that functioned as a proton pumping element. The proposed system features a quick responsive uptake/release rate that was about 10 times the adsorption/desorption rate with an open circuit. The potential-responsive film system exhibited a high electroactivity because of an acidic micro-environment for the nitrogen atoms in the PANI chains due to protons available on the electronegative α-ZrP nanosheets and their ion exchangeability. The uniform and dense hybrid film was formed on platinum electrodes using a one-step electrosynthesis based on unipolar pulse electrodeposition (UPED). By simply switching the operating potential applied to the electrode, heavy metal uptake onto the film from aqueous solutions and metal release for film regeneration were accomplished. This film system is shown to be a promising alternative to conventional techniques for heavy metal capture from wastewater.