Oil-infused feed spacers for biofouling inhibition

A novel approach is investigated for preventing biofouling of spacer filaments, which are an essential part of spiral-wound modules used in membrane-based desalination. Biofouling, caused by the growth and multiplication of microorganisms on the membrane surface, can significantly impact the efficiency and cost-effectiveness of the desalination process. Herein, a method is proposed for fabricating modified feed spacers based on oil-infused slippery substrates made of polydimethylsiloxane (PDMS). These feed spacers, when infused with silicone oil, create a stable, extremely slippery interface that exhibits exceptionally low bacterial adhesion and prevents biofilm formation, especially under flow conditions. By examining the effect of the silicone oil's viscosity, we determined the optimal ratio of the curing agent for fabricating the oil-infused feed spacer. Results showed a substantial reduction of bacterial adhesion to the surface for all tested oil viscosities, particularly under dynamic conditions. Furthermore, even where bacterial adhesion occurred, primarily on samples infused with lower-viscosity oil, it could be easily removed by simple rinsing. Overall, the oil-infused feed spacer demonstrated exceptional biofilm inhibition, providing preliminary indication of the potential offered by this promising approach.