Abstract
This study investigated the modification of polyethersulfone (PES) ultrafiltration membranes with TiO(2) and Fe(2)O(3)-TiO(2) nanoparticles to enhance their hydrophilicity and biofouling resistance against the marine microalgae Chlorella vulgaris. It is a common freshwater and marine microalga that readily forms biofilms on membrane surfaces, leading to significant flux decline and increased operational costs in ultrafiltration processes. The microalgae cells and their extracellular polymeric substances (EPS) adhere to the membrane surface, creating a dense fouling layer that impedes water permeation. The modified membranes were characterized using contact angle measurements, scanning electron microscopy, and pure water flux/resistance tests. Short-term ultrafiltration experiments evaluated the membranes' antifouling performance by measuring flux decline, flux recovery ratio, and relative flux reduction during C. vulgaris filtration. The TiO(2) membrane showed improved hydrophilicity and antifouling over the pristine PES membrane, while the Fe(2)O(3)-TiO(2) nanocomposite membrane exhibited the best performance. It reduced the water contact angle and showed only a 5% relative flux reduction compared to 60% for the pristine membrane. SEM images confirmed reduced microalgal deposition on the nanocomposite surface. Long-term tests with microalgal cells under dark and visible light conditions in saline water further assessed the membranes' biofouling resistance. The Fe(2)O(3)-TiO(2) membrane maintained 59 L/m(2) h water flux under visible light after immersion in the microalgal solution, outperforming the pristine (38 L/m(2) h) and TiO(2) (52 L/m(2) h) membranes. This superior antifouling was attributed to photocatalytic generation of reactive oxygen species inhibiting microalgal adhesion. This study demonstrates a promising strategy for mitigating biofouling in membrane-based water treatment and desalination processes.