Exploring the potential usage of 3D printed membranes combined with PVDF coating in direct contact membrane distillation

3D printing technology has drawn considerable attention in various applications due to its appealing features such as freedom of design, quick fabrication, automation, no solvent discharge, and less environmental issues. The feasibility of using 3D printed (3DP) membranes in membrane distillation (MD) was explored for the first time. Polyamide (PA) membranes were printed in a laser sintering (LS) technology and further coated with thin poly(vinylidene fluoride) (PVDF) layers to reduce the pore size. Results show that the PVDF layers could effectively reduce the membrane pore size from 15.9 +/- 5.3 mu m to 1.0-2.5 mu m. Additionally, due to the granular and rough surface of the 3DP membranes, the hydrophobicity of the composite membranes (100 degrees-130 degrees) is greater than for the PVDF membranes manufactured on the flat substrates (similar to 70 degrees). However, the great thicknesses of the PA membranes of 359.6 +/- 38.9 mu m lead to relatively thick composite membranes. The PVDF@3DP membranes show DCMD fluxes of 5-10 kg/(m(2).h) at a temperature difference of 40 degrees C. The overall results indicate that the 3DP substrate significantly affect the composite membrane properties and MD performance. Therefore, improving the printed membrane's porosity and thickness will be advantageous to prepare membranes with quick fabrication and less solvent discharge.

Automated summary

The study explored the feasibility of using 3D printed membranes in membrane distillation for the first time, and results showed that coating polyamide membranes with poly(vinylidene fluoride) layers effectively reduced pore size. However, the relatively thick 3D printed membranes, despite their greater hydrophobicity compared to PVDF membranes, significantly affected membrane properties and MD performance.