Porous ceramic membranes from coal fly ash with addition of various pore-forming agents for oil-in-water emulsion separation

Coal fly ash (CFA) is a substitute material for ceramic membrane which can effectively reduce the preparation cost. However, CFA based ceramic membranes usually show insufficient mechanical strength for application. Revealing pore-forming mechanisms of different pore-forming agents in membranes preparation is of great significance to improve mechanical strength without harming permeability. In this work, three different pore-forming agents, carbon powder, dolomite and dextrin, were adopted to prepare CFA membranes. Characters including porosity, pore size distribution and permeability of membranes were comparatively analyzed. Effects of pore-forming agents on membranes were discussed. The membrane with dextrin at 1200 °C sintering showed the best comprehensive properties. Its porosity, flexural strength and Darcian permeability coefficient were 39.46 %, 35.56 MPa and 3.84 × 10 −14 m 2 , respectively. Application in oil-in-water emulsion separation indicated higher than 94 % oil rejection. This research provides experimental bases for improving performances of low-cost CFA membranes, thereby conducive to engineering applications.