Fabrication of spherically-structured ceramic membrane for harsh high-salinity wastewater treatment via membrane distillation

Abstract

Ceramic membrane with long service life and excellent chemical stability is promising for membrane distillation (MD) in high-salinity wastewater treatment. However, traditional ceramic membranes face low flux and failure to achieve the desired long-term stability due to the irregular particle packing in the membrane layer. The inferior stability stems from the non-uniform pore size distribution of the membrane layer caused by irregular particles, which further leads to the clogging of large pores by contaminants, such as salt crystals and dye molecules. To enhance the stability of MD performance, spherical and uniform Al₂O₃ particles were adopted to fabricate membrane layers. These particles can homogenize the pore size distribution of the membrane layer that significantly improves the anti-fouling performance and stability of the membranes. To tackle the problem of low flux, a “prefilling” strategy using polyvinyl butyral (PVB) solution is adopted in this work, which can effectively eliminate the intermediate layer and enhance the MD flux. First of all, the membrane supports were fabricated by optimizing the fabrication parameters, particularly for the sintering aids. In the membrane fabrication process, the PVB concentration and the solid content were investigated in detail. The final pure vapor MD flux of ceramic membranes was 28.91 kg·m⁻²·h⁻¹ with a mean pore size of 0.24 μm. Subsequently, the superiority of ceramic membranes in treating harsh high-salinity wastewater was demonstrated through three harsh system. They all exhibit favorable flux and stability. In general, this work introduced an innovative approach to fabricate high-performance spherically-structured ceramic membrane for membrane distillation in harsh high-salinity wastewaters.