CFD-Based Modeling and Experimental Evaluation of Fouling in Graphene Oxide-Modified Polyethersulfone Ultrafiltration Membranes

Membrane fouling remains a major limitation in ultrafiltration processes because it reduces permeate flux and increases hydraulic resistance during operation. In this study, polyethersulfone ultrafiltration membranes containing different graphene oxide loadings of 0, 1, 3, and 5 wt% were fabricated and evaluated experimentally. Water contact angle measurements were used to assess membrane surface wettability, while cross-flow filtration experiments were performed to determine permeate flux decline under fouling conditions. A three-dimensional computational fluid dynamics model was developed in COMSOL Multiphysics by coupling fluid flow, solute transport, and a resistance-in-series fouling formulation. The model was used to simulate temporal changes in permeate flux, pressure drop, and fouling resistance. Increasing graphene oxide loading from 0 to 3 wt% reduced the water contact angle from 78.5° to 58.0°, indicating improved membrane hydrophilicity. The membrane containing 3 wt% graphene oxide exhibited the highest initial flux and better flux retention compared with the unmodified and 5 wt% graphene oxide membranes. At 5 wt% loading, membrane performance declined, which was attributed to possible nanoparticle agglomeration and increased transport resistance. The simulated flux-decline trend was compared with the experimental observations and showed satisfactory agreement after model calibration. The simulated flux-decline trend was calibrated against one experimental flux dataset for the 3 wt% GO-PES membrane over a 30-min filtration period using a linear-regression-based adjustment of the simulated initial flux and overall trend. After calibration, the relative deviations between the simulated and experimental flux values remained below 5% over the investigated period. Graphene oxide-modified PES ultrafiltration membranes were experimentally evaluated. A 3 wt% GO loading reduced the water contact angle from 78.5° to 58.0°. The 3 wt% GO membrane showed improved flux retention under fouling conditions. CFD simulations captured temporal changes in flux and fouling-induced resistance.