3D-printing enables geometry-optimized ceramic membranes with minimizing mass transfer resistance for environmental application

Membrane separation technology, with its features of high efficiency and environmental sustainability, is playing an increasingly important role in the field of energy conservation and emission reduction. Membrane structure design has shown high advantages in reducing mass transfer resistance and enhancing separation efficiency. In this study, 3D printing technology was employed to fabricate a direct-channel structured alumina-mullite ceramic membrane to enhance membrane separation efficiency. A ceramic slurry was used as raw material to precisely manufacture ceramic membrane as the digital model, achieving high curing depth of 200 μm and low curing width of 50 μm. Moreover, in-situ mullite reaction was employed to form sintering necks among ceramic particles to enhance the bending strength. The effects of solid content and sintering temperature on the membrane properties were systematically investigated. When the solid content was 75 wt% and sintering temperature was 1400 °C, the ceramic membrane with conventional structure exhibited a pore size of 1.1 μm and pure water flux of 1698 L/(m 2 ·h·bar). In contrast, the direct-channel structured ceramic membrane exhibited a high pure water flux of 4700 L/(m 2 ·h·bar), which was ∼3 times higher than those of the conventional ones. This improvement of permeability could be attributed to the optimized mass transfer process that was confirmed via computational fluid dynamics (CFD) simulation. To demonstrate the potential application of this ceramic membrane in the environmental sustainability, oil/water emulsion separation was taken as an example. The membrane demonstrated high separation efficiency of above 99% and a stable water permeance of 130 L/(m 2 ·h·bar) during oil/water emulsion filtration. This work provides a fundamental basis to advance the development of structurally designed ceramic membranes for environmental sustainability.