Prefilling polymers to regulate interfacial hierarchical structures of ceramic membranes for enhanced membrane performance

Superhydrophobic ceramic membranes show great robust properties for membrane distillation (MD) to recycle fresh water from high-salinity wastewater. In this work, a prefilling method was proposed to fill the polymers in the pore channels of the ceramic membranes before in-situ growing hierarchical ceramic nanoflowers. It was demonstrated that the ceramic nanoflowers just grew on the membrane surface and did not block the inner channels of the ceramic membranes. In addition, these nanoflowers regulated pore size of the membrane and enabled superhydrophobic properties simultaneously. The effects of the Al₂(SO₄)₃ concentration, hydrothermal treatment time, sintering temperature of Al₂O₃ nanoflowers, and the prefilling process on the performance of the membrane were investigated. The results indicated that the pore size of the ceramic membrane decreased from 0.635 μm to 0.214 μm after in-situ growing Al₂O₃ nanoflowers. Meanwhile, the resulting water contact angle of the membranes increased from 135.3 ± 1° to 153.2 ± 0.6°. The resulting membrane exhibited high stable performance and salt rejection when treating the salinity-contained wastewaters. This work paved a new way to improve the MD performance of ceramic membranes.