Phase inversion/sintering-induced porous ceramic microsheet membranes for high-quality separation of oily wastewater

Ceramic microfiltration membranes with superior chemical and mechanical stability for sustainable operation under harsh conditions have demonstrated great potential for industrial wastewater treatment. In this study, low-cost ceramic microsheet membranes with a thickness of sub-0.5 mm that possess superhydrophilic and underwater superoleophobic properties were fabricated from an Al₂O₃-rich Al₂O₃/polysulfone composite slurry via a phase inversion/sintering strategy. The cross-sectional morphologies of these phase inversion-induced composite films appear as ceramic green bodies that can be precisely controlled by tuning the operation parameters during the classic phase-inversion process of a polymer, which allows the morphology to withstand a subsequent high-temperature (1250 °C) sintering process. The thinner nature (<0.5 mm), suitable pore size (~100 nm), and a superior wetting chemistry make these ceramic microsheets very promising for the separation of oil-in-water emulsions with an outstanding separation efficiency of >99% and a much higher emulsion permeability of ~3,000 L/(m² h bar), which is 2 orders of magnitude higher than most commercially available microfiltration membranes that are capable of similar levels of separation performance. This process resulted in a favorable membrane that combines robustness under complex chemical environments with low cost for both materials and processing approaches, which should facilitate its practical application in the industrial treatment of oily wastewater.