Low-cost fabrication of bauxite-based ceramic membranes with sandwich-structured for oil-in-water separation

This study developed a bauxite-based ceramic microfiltration membrane with a sandwich structure, featuring dual mullite-whisker separation layers surrounding a coarse-particle intermediate layer, fabricated through a simplified sieving and co-sintering process. The separation layers, derived from fine bauxite particles, formed high-aspect-ratio mullite whiskers on their surfaces, imparting superhydrophilic properties. The intermediate layer, built from coarse bauxite particles, enhanced the flow rate due to its macroporous structure. The integrated sandwich design delivered exceptional oil/water separation efficiency (96.9 %) and a high pure water flux of 669.3 L·m⁻²·h⁻¹ , balancing selectivity and permeability. The membrane also showed remarkable durability, retaining a water flux of 547.3 L·m⁻²·h⁻¹ after simple cleaning and recycling, with separation performance for emulsions of varying concentrations dropping by less than 1.5 % after 9 cycle tests. This cost-effective, scalable fabrication method highlights the potential of bauxite-based ceramic membranes for efficient and sustainable oil-in-water separation applications.