Polycarbosilane-Derived porous ceramic thin membranes with enhanced mechanical strength and Tunable crystal structures for oily wastewater treatment

Porous ceramic membranes possess significant potential for wastewater treatment, with their performance largely determined by material composition and structure attributes. In this study, thin porous ceramic membranes with varying crystal types—amorphous SiO₂/Al₂O₃, cristobalite/Al₂O₃ and mullite/Al₂O₃—were developed using Al₂O₃, polycarbosilane (PCS) and polysulfone (PSf) via phase inversion-sintering process. As a polymeric precursor, PCS was effectively dispersed among Al₂O₃ particles through co-phase inversion with PSf. Subsequent sintering at different temperatures transformed PCS into ceramic material with distinct crystal structures, imparting unique properties to the membranes. This work systematically explored the crystal evolution process, morphological structure, and mechanical strength of these ceramic membranes. The membranes exhibited high porosity (56–73.5 %) and crushing strength (5.2–38.2 MPa), along with adjustable pore sizes (250–90 nm) and a narrow pore size distribution. Furthermore, the filtration performance of the membranes was evaluated for the separation of a 1000 mg/L oil-in-water (O/W) emulsion, achieving high and stable O/W emulsion permeance (1327–1967 LMH/bar) and excellent oil rejection (97.3–99.4 %). Additionally, the membranes demonstrated outstanding anti-fouling properties, with a flux recovery rate of 90.8 % achieved through simple chemical cleaning.