Iranian Association of Chemical Engineering (IAChE) Iranian Journal of Chemical Engineering (IJChE) 1735-5397 23 1 2026 06 01 Diazonium-Based Surface Functionalization of PES Nanofiltration Membranesto Improve Antifouling Properties and Heavy Metal Removal 35 61 244007 10.22034/ijche.2026.575107.1587 EN Mina Shekarbeigi Arak University, Faculty of Engineering, Department of Chemical Engineering, Arak, Iran Fahime Parviziyan Arak University, Faculty of Engineering, Department of Chemical Engineering, Arak, Iran 0009-0009-7063-1119 SayedMohsen Hosseini Arak University, Faculty of Engineering, Department of Chemical Engineering, Arak, Iran 0000-0002-3974-5312 Journal Article 2026 02 17 In this study, Nano filtration (NF) membranes, composed of polyethersulfone (PES) modified with titanium dioxide (TiO₂) nanoparticles, were fabricated using the phase inversion method. By grafting aniline oligomers onto the surface of the modified membrane, the final membrane with the structure of PES NF/TiO₂/AO was fabricated. The morphology of the final membrane was investigated using FESEM, EDX and FTIR analyses. The membrane separation performance was evaluated through measuring the contact angle and pure water flux (PWF), flux recovery ratio (FRR%), and salt rejection tests using Na₂SO₄ and MgSO₄ solutions. The highest PWF (3.66 kg/(m^2.h)) was obtained with the final modified membrane compared to the initial membrane at an operating pressure of 4.5 bar, which can be attributed to the increased hydrophilicity caused by the surface modification of the initial membrane. The removal efficiencies for heavy metals Pb and Cu using the pristine membrane were measured to be 28.2% and 43%, respectively, while the optimized membrane showed the significantly improved rejection rates of 99.97% and 94%. Furthermore, the total fouling rate of the original membrane was approximately 70.4%, which was reduced to 47.4% in the modified membrane. The irreversible fouling was reduced from 44.5% in the original membrane to 32.6% in the optimized membrane, indicating an improvement in the antifouling performance of the modified membrane. The results suggest that the PES NF/TiO₂/AO modified membrane can be considered an effective approach for enhancing the physical and chemical properties of membranes, as well as their separation performance, particularly for the removal of heavy metals. https://www.ijche.com/article_244007_ea98c5685b99cdba0bf213a524eb74b0.pdf