Porous SiC Ceramic Membranes Prepared by Low-Temperature Sintering: Filtration Performance in Mine Water Treatment and Alkaline Cleaning Stability

Low-temperature fabrication of porous silicon carbide (SiC) ceramic membranes using secondary bonding phases offers an alternative to conventional high-temperature sintering. This study compared aluminium-sol- and silica-sol-derived SiC membranes fabricated in air at 1300 °C with sol additions of 10–40 wt.%, focusing on pore structure, mechanical strength, mine-water filtration, fouling behaviour, and alkaline oxidative cleaning. X-ray diffraction revealed weak features potentially associated with mullite formation in the aluminium-sol membranes, while SiO2-related phases were observed in the silica-sol membranes. Increasing sol content reduced porosity, pore diameter, and permeate flux while improving flexural strength. SiC-30%Al-sol provided a favourable performance balance, achieving a flexural strength of 25.2 MPa, a permeate flux of approximately 230 L m−2 h−1 after 40 min of mine-water filtration, and a final permeate turbidity of approximately 0.3 NTU. For SiC-30%Al-sol, the cake-filtration model provided the best fit over the 5–20 min interval, without establishing the dominant fouling mechanism. Following a single NaOH/NaClO cleaning cycle, SiC-30%Al-sol exhibited 90.4% flux recovery and 15.1% flexural-strength loss. Aluminium-sol membranes generally showed smaller strength losses and surface-roughness changes than silica-sol membranes under the tested conditions. These findings highlight the influence of bonding-phase chemistry on membrane performance, although repeated cleaning and post-cleaning pore-structure measurements are needed to establish long-term durability.