Reagent-free thermal regeneration restores severely oil-fouled ceramic membranes

Severely oil-fouled ceramic membranes that lose recoverability after conventional cleaning represent a replacement-prone but underutilized inorganic separation resource. Here, we demonstrate a reagent-free thermal regeneration strategy for restoring oil-fouled Al 2 O 3 ceramic membranes and examine its applicability to SiC membranes. Under optimized conditions of 400 °C for 30 min, the regenerated Al 2 O 3 membrane achieved an initial flux recovery ratio of nearly 99% and retained ~97% flux recovery after five fouling-regeneration cycles, while the emulsified-oil rejection remained ~96-98%. Repeated alkaline cleaning led to substantial irreversible flux loss, whereas subsequent thermal regeneration restored the flux recovery to ~96%, highlighting its value for membranes after repeated alkaline-cleaning failure. Structural and thermal analyses indicate that thermal treatment promotes the transformation and removal of oil-emulsion-derived organic residues from the fouled surface and pore-associated regions, thereby reopening transport pathways while preserving the ceramic pore architecture and crystal phase. The direct-input comparison shows that thermal regeneration requires ~11% of the direct-input cost and ~13% of the electricity input associated with pristine membrane fabrication. This work provides a practical basis for restoring severely oil-fouled ceramic membranes before replacement in oily wastewater treatment.