High-purity SiC ultrafiltration membrane with triple-layer asymmetric structures constructed from multiscale SiC powders

Silicon carbide (SiC) ceramic membranes fabricated by recrystallization sintering can be used in some harsh environments because of their remarkable chemical and thermal stabilities. However, the commercial membranes can only meet the demands of microfiltration applications because of the challenge in pore-size control during recrystallization sintering. Here, a SiC ultrafiltration membrane with triple-layer asymmetric structures was prepared with micro-scale SiC particles for the substrate and nano-scale SiC particles for the selective layer. Defects-free selective layers were successfully coated on the high-purity SiC substrate by spin coating. The average pore size of the membrane was 60 nm when sintered at 1300 ℃. The surface roughness of the membrane increased with the increase in sintering temperature, leading to the improvement in hydrophilicity. Oil-in-water emulsion filtration analysis found that the oil rejection of the membrane exceeded 99.9 %. Thus, this SiC UF membrane provides new possibility to treat the corrosive and oily wastewaters.