Fe3+-modified polyamide membrane with a porous network structure: Rapid permeation and efficient interception of trace organic compounds

Abstract

Forward osmosis (FO) is a promising technology in the treatment of trace organic substances. However, the development of this technology is limited by membrane material selection and the long-term chemical stability and durability of the membrane. Whereas ibuprofen, a representative trace organic substances that is hydrophobic and negatively charged, poses potential environmental hazards due to its bioactivity. In this work, polyethersulfone (PES) membranes were modified with iron metal complexes via chelation reactions to achieve high rejection rates for ibuprofen. The Fe3+-modified composite FO membrane increased the ibuprofen rejection rate to 98.3 % compared to less than 80.0 % for the original PES membrane. Additionally, the modified membrane enhanced water flux by at least 25.0 % and reduced reverse solute flux to a maximum of 73.0 % of that of the polyamide composite membrane, while significantly improving anti-fouling capabilities. Membrane characterization results revealed that the significant enhancement in the ibuprofen retention rate was due to the addition of a negative charge by forming complexes with Fe3+, which increased intermolecular interactions. Additionally, the dense network structure developed by the Fe3+-EDTA-2Na modification also contributed to the enhanced membrane performance.