Novel chelating polyacrylonitrile membrane for efficient capture of Cu2+, Pb2+ and Fe3+

A novel chelating PAN-oxime@DTC membrane was synthesized by grafting dithiocarbamate (DTC) and oxime onto the polyacrylonitrile (PAN) membrane surface, leading to the strong adsorption ability to the heavy metal ions such as Cu2+, Fe3+ and Pb2+, and therefore, the promising performance on purifying wastewater. The membrane structure, morphology, mechanical, transport, and thermal properties were verified by Fourier-transform infrared spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), scanning electron microscopy (SEM), mechanical test, water flux and thermogravimetric analysis (TGA), respectively. Compared with PAN or PAN-oxime membrane, the PAN-oxime@DTC membrane exhibited enhanced tensile stress, thermal stability, solvent tolerability, hydrophilicity, porosity, water flux, antibacterial ability, and much higher adsorption capacity for Cu2+, Fe3+ and Pb2+ and the maximum capacity for adsorbing Cu2+, Fe3+ and Pb2+ were up to 277.78, 232.56 and 256.41 mg/g, respectively. Additionally, the kinetic and isotherm models were deliberated to determine the adsorption performance of the PAN-oxime@DTC membrane, as well as the adsorption mechanism of heavy metal ions. Notably, excellent retention performance of PAN-oxime@DTC membrane was evidenced by more than 99 % Cu2+ and Fe3+ and 90 % Pb2+ being adsorbed by the membrane from the wastewater, and the membrane maintained similar retention behavior with the presence of Ca2+ and Mg2+ in the aqueous phase. The adsorption mechanism was further understood by quartz crystal microbalance with dissipation (QCM-D), FTIR, density functional theory (DFT), and XPS. More importantly, the membrane could be efficiently regenerated by treating with 1 M HCl solution for at least 3 adsorption cycles.