Preparation and characterization of a new negatively charged polytetrafluoroethylene membrane for treating oilfield wastewater

► The traditional PTFE membrane is pretreated by using the atmospheric pressure glow discharge (APGD) plasma, and then surface of the PTFE membrane is modified by the photo-induced graft polymerization of 2-acrylamido-2-methyl-propyl-sulfoacid (AMPS). ► Formation of a polymerized AMPS layer on the PTFE membrane has been detected and confirmed by using the attenuated total reflection with both the infrared spectroscopy (ATR-IR) spectra and the scanning electron microscope (SEM) analysis. ► The optimum grafting efficiency is found to achieve at 15.1% volumetric concentration of AMPS monomer, 30 min UV irradiation time, and 5.0% volumetric concentration of polymerization initiating agent. ► The streaming potential and zeta potential of the modified PTFE membrane are measured at various conditions, confirming the fact that the modified PTFE membrane is negatively charged. ► The antifouling performance of the modified PTFE membrane has been significantly increased for treating and recycling the oilfield wastewater in comparison with the original PTFE membrane.