Development of porous mullite and mullite-Al2O3 composite for microfiltration membrane applications

•Porous mullite with interlocking crystals was developed from clay and AlF3·3H2O.•Alumina addition enhanced strength and mullitisation (∼96% at 1300 °C) of the matrix.•Apparent porosity of 64% with a flexural strength of 43 MPa obtained at 1400 °C.•Narrow pore size distribution was obtained, suitable for microfiltration applications.•Interlocking crystals forming the microstructure resulted in high water flux.