Integration of Porous and Permeable Poly(ether sulfone) Feed Spacer onto Membrane Surfaces via Direct 3D Printing

This research details the use of direct three-dimensional (3D) printing technology to create membranes with integrated square-shaped porous feed spacers made of poly(ether sulfone) (PES). Various concentrations of PES (18, 20, 22, 25, and 28 wt %) in the 3D printing solution were employed to evaluate the impact of solution viscosity on 3D-printed spacer fidelity and membrane performance. Comparative analysis with the FS18 membrane, which utilizes a plastic polylactic acid (PLA) feed spacer and flat PES membrane, revealed a substantial improvement in pure water flux (31.0–130%) for the integrated membranes, mainly attributed to the augmented effective surface area (2.41–39.7%) created by the porous PES feed spacer patterns. However, this enhancement is viscosity-dependent, as evidenced by the reduced spacer pattern fidelity in the P18 (18 wt % PES) membrane with low-viscosity 3D printing solution, leading to diminished overall membrane effectiveness. Remarkably, when compared to the flat membrane, the integrated membranes (except P18 membrane) demonstrated better antifouling behavior, regardless of whether a plastic PLA feed spacer was used or not. This is attributed to elevated shear stresses on the porous spacer pattern peaks and induced turbulence, acting as a protective shield against severe membrane fouling. Overall, this study highlights the effectiveness of direct 3D printing in seamlessly integrating porous PES feed spacers onto membrane surfaces, offering potential for optimization and exploration of diverse polymers in the 3D printing process.