Construction of bilayer PTFE/ceramic membrane with narrow pore size distribution for the treatment of boiler blowdown water

A bilayer PTFE/ceramic composite membrane with a narrow pore size distribution was fabricated via a co-sintering method for efficient treatment of boiler blowdown water. A micron-sized PTFE interlayer was first deposited on a macroporous ceramic support to reduce surface pore size and prevent nanoparticle infiltration. Subsequently, a nanoparticle-based PTFE ultrafiltration top layer was formed by co-sintering with polyvinyl alcohol (PVA) as a binder, yielding a defect-free, crack-free selective layer. The resulting membrane exhibited a uniform pore size centered at 67 nm and a strong hydrophobicity. In vacuum membrane distillation, the membrane achieved a stable water flux and salt rejection above 99.9 % across a wide temperature range without wetting. It also demonstrated excellent rejection of phosphate and silicate during simulated boiler blowdown treatment, maintaining over 99.9 % removal and stable flux for more than 3000 min. These results highlight the membrane’s excellent anti-wetting, anti-fouling, and thermal stability, making it a promising candidate for the sustainable treatment of high-temperature industrial wastewater.